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The distribution of the enzyme cytochrome oxidase (CO) in continuous series of parasagittal sections from field 17 and frontal sections of the dorsal nucleus of the lateral geniculate body (LGB) from normal kittens and adult cats was studied. In all cats apart from neonates, layer IV showed regularly alternating areas with above-background levels of CO activity ("spots"). There was a significant increase in the contrast of the "spots" from days 13 to 21, which was followed by a significant decrease from days 48 to 93. These changes coincided with ontogenetic changes in the level of visual system plasticity. There were no differences in CO activity between layers A and A1 of the dorsal nucleus of the LGB. It is suggested that the non-uniform distribution of the level of functional activity of neurons in field 17 reflects the formation of columnar cortical structures during the critical period of postnatal ontogenesis.

Cytochemical estimation of COX activity and morphometric measurement of mitochondrial ultrastructure were carried out in organelles from adult and old rats. Although no age-related difference was found in cytochemical precipitate (CPA) and mitochondrial area (MA), the ratio CPA:MA (R) decreased by 25.7% in aging. R was the same in oversized mitochondria, but in smaller organelles it was significantly decreased during aging. R reports on the functional mitochondrial surface involved in energy providing mechanisms; thus, by revealing age-related differences, these data suggest that the COX preferential cytochemistry associated with morphometry may serve as a reliable and sensitive mitochondrial morphofunctional checkup procedure.

Aerobic exercise increases oxidant stress and leads to apoptosis of mouse intestinal lymphocytes (IL). The purpose of this study was to determine whether freewheel running prevents IL loss 24 h after a bout of strenuous exercise. Mice were randomly assigned to in-cage running wheels with 24 h access (WR) or individual cages without running wheels (NR) for 4 months. WR mice accumulated 364 km over 4 months and had higher cytochrome oxidase activity in the plantaris (p < .05), indicative of training. Total intestinal, CD3alphabeta, CD3gammadelta, CD8alpha, and CD8beta lymphocytes and intracellular glutathione were significantly lower in WR and NR mice 24 h post-exercise. The number of CD4 IL decreased 24 h after exercise in NR (p < .01) but not in WR mice relative to their respective no exercise controls. Thus, freewheel running in mice for 4 months prevented CD4 IL loss after acute exercise.

One approach to assess neuroendocrine response to portal hypertension in short-term portal vein-stenosed rats consists in studying metabolic and functional activity patterns in adrenal glands using mitochondrial enzyme cytochrome c oxidase (COX) as a histochemical marker. Male Wistar rats were divided into two groups: a control group (Group I; n = 8), in which the animals did not undergo any operative intervention, and a triple calibrated portal vein stenosis group (TPVS) (Group II; n = 7). The sections of suprarenal glands were histochemically stained for COX and the optical densitometry was measured by a computer image analyzer attached to a microscope. In TPVS rats, COX activity in the adrenal gland cortex is lower than in control rats and affects the fascicular (52.30, 47.16-60.98, vs. 67.12, 60.31-73.89, p = .002), glomerular (49.68, 46.19-53.56 vs. 70.47, 64.64-73.51, p.001), and reticular (47.35, 35.63-54.39, vs. 55.37, 49.76-58.97; p.05) layers. In contrast, COX activity in the adrenal gland medulla is similar in TPVS rats and in control rats (29.91, 29.54-31.18, vs. 29.67, 28.95-30.23). The changes in adrenocortical COX activity in short-term-TPVS rats could constitute a pathogenic factor for both splanchnic and systemic hyperdynamic circulations, described in this experimental model of prehepatic portal hypertension.

The present study investigated the functional involvement of the rat hippocampal formation in easy and difficult visual discrimination learning by measuring regional brain cytochrome oxidase (C.O.) activity, an index of neuronal metabolic activity. The results showed that learning was related to C.O. activity in the CA field and the dentate gyrus of the hippocampal formation of rats in the difficult discrimination, whereas learning was related to C.O. activity only in the dentate gyrus of rats in the easy discrimination. The results suggest that difficult visual discrimination learning required greater involvement of the hippocampal formation than easy visual discrimination learning.

Mitochondrial NADH-dehydrogenase, succinate dehydrogenase and cytochrome oxidase activities of peripheral blood leukocytes of rats with the grafted Guerin's carcinoma were studied in the dynamics of oncogenesis under the conditions of the preliminary low-level irradiation. Tumor growth was accompanied by a decrease in NADH-dehydrogenase activity, an increase of succinate dehydrogenase activity. Cytochrome oxidase activity of leucocytes remained at the control level up to the terminal stages of tumor growth. Preliminary low-level irradiation of the tumor bearing animals caused a tendency to the decrease of enzymatic activities studied. This tendency was observed from the initial stages of oncogenesis.Issledovana NADN-degidrogenaznaia, suktsinatdegidrogenaznaia i tsitokhromoksidaznaia aktivnost' mitokhondriĭ leĭkotsitov perifericheskoĭ krovi krys s transplantirovannoĭ kartsinomoĭ Gerena v dinamike onkogeneza v usloviiakh predvaritel'nogo oblucheniia malymi dozami radiatsii. Pokazano, chto v dinamike rosta kartsinomy Gerena nabliudaetsia tormozhenie NADH-degidrogenaznoĭ aktivnosti na fone aktivatsii suktsinatdegidrogenazy c sokhraneniem na terminal'nykh étapakh rosta opukholi tsitokhromoksidaznoĭ aktivnosti na urovne znacheniĭ kontrolia. V usloviiakh predvaritel'nogo nizkodozovogo oblucheniia opukholenositeleĭ nabliudaetsia tendentsiia k tormozheniiu issleduemykh fermentativnykh aktivnosteĭ, nachinaia uzhe s nachal'nykh étapov onkogeneza.

Increased ventricular ANF-mRNA is observed as a compensating mechanism in response to many forms of overload including chronic exercise. It is unknown if exercise-induced increases in ANF expression are mediated at the transcriptional level and whether specific cis-element(s) may be involved. To study this, rats were injected with several different ANF reporter plasmids. Following recovery, the animals were made to swim for 60 minutes per day. One week of swim training significantly increased plantaris muscle cytochrome oxidase activity and left ventricular ANF-mRNA levels. Exercise training significantly increased ANF reporter expression. We have previously demonstrated that a single cis-element (POE) mediates pressure overload activation of ANF expression during developing hypertrophy. Site-specific mutation of the POE cis-element (-495/-489) within the ANF promoter also ablated exercise-induced increases in reporter expression indicating that the POE site was critical. Further, exercise increase the expression of a POE-heterologous construct, indicating that the POE cis-element alone was sufficient for exercise induced activation. Gel mobility shift analysis, using the POE cis-element as a probe, determined that a single complex was formed and that training did not influence the DNA-protein binding pattern. These results indicate that increased ANF expression is mediated at the transcriptional level as an early adaptation to chronic exercise. The same cis-element that mediated pressure-overload activation of ANF reporter expression was also found to be critical and sufficient to mediate exercise-induced increases in ANF reporter expression. These findings suggest that there may be some overlap in the response to physiological and pathological forms of overload during the phase of developing hypertrophy.

Freezing lesions to the developing cortical plate of rodents results in a focal malformation resembling human 4- layered microgyria, and this malformation has been shown to result in local and widespread disruptions of neuronal architecture, connectivity, and physiology. Because we had previously demonstrated that microgyria caused disruptions in callosal connections, we hypothesized that freeze lesions to the postero-medial barrel sub-field (PMBSF) in one hemi- sphere would affect the organization of this barrel field contralaterally. We placed freeze lesions in the presumptive PMBSF of neonatal rats and, in adulthood, assessed the architecture of the ipsilateral and contralateral barrel fields. Malformations in the PMBSF resulted in a substantial decrease in the number of barrels as identified by cytochrome oxidase activity. More importantly, we found an increase in the total area of the contralateral PMBSF, although there was no difference in individual barrel cross-sectional areas, indicating an increase in the area of inter-barrel septae. This increase in the septal area of the contralateral PMBSF is consistent with changes in callosal and/or thalamic connectivity in the contralateral hemisphere. These results are another example of both local and widespread disruption of connectional architecture following induction of focal microgyria. q 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.

The present study was undertaken to determine the role of metabolic disturbance in noise-induced hearing loss by histochemical studies of cytochrome oxidase activity. Adult normal albino guinea pigs were used. The experimental animals were exposed to broad-band noise at 105 dB SPL for 24 h. The control animals were not exposed to the noise. The thresholds of the auditory brainstem response (ABR) of all guinea pigs were measured 3 times: before noise exposure, 1 day and 1 month later. The difference between the ABR thresholds before and after noise exposure was statistically significant. Vibratome sections of decalcified cochleae of the noise-exposed (n = 8) and control groups (n = 4) were incubated with Spector’s medium and embedded with Epon. Thin sections (2 µm) and ultrathin sections (100 nm) were cut to observe cytochrome oxidase activity in the stria vascularis under light and electron microscopes, respectively. A decreased activity of cytochrome oxidase was consistently shown in the normal-appearing stria vascularis of most noise-exposed ears. Acoustic trauma has an adverse effect on cytochrome oxidase activity in the stria vascularis as well as on hearing. A decrease in the activity of cytochrome oxidase implicates that metabolic damage may play a role in noise-induced hearing loss.

This paper evaluates the changes of cytochrome oxidase (CO) activity that take place in the suprachiasmatic nucleus (SCN) during the light-dark cycle. CO is a mitochondrial energy-generating enzyme used as a marker of neural oxidative metabolism. We measured CO activity using quantitative histochemistry calibrated with brain tissue standards and a computerized analysis image system. The results indicate that the CO enzyme activity changes on the basis of a circadian pattern, with the higher levels during the light phase (P0.0001). These changes are detected over a period of hours, in accordance with other studies on the possible short-term regulation of CO activity in the nervous system. It is, therefore, possible to apply this methodology to the study of the SCN and other brain areas which show functional rhythmicity.

V2 has long been recognized to contain functionally distinguishable compartments that are correlated with the stripelike pattern of cytochrome oxidase activity. Early electrophysiological studies suggested that color, direction/disparity, and orientation selectivity were largely segregated in the thin, thick, and interstripes, respectively. Subsequent studies revealed a greater degree of homogeneity in the distribution of response properties across stripes, yet color-selective cells were still found to be most prevalent in the thin stripes. Optical recording studies have demonstrated that thin stripes contain both color-preferring and luminance-preferring modules. These thin stripe color-preferring modules contain spatially organized hue maps, whereas the luminance-preferring modules contain spatially organized luminance-change maps. In this study, the neuronal basis of these hue maps was determined by characterizing the selectivity of neurons for isoluminant hues in multiple penetrations within previously characterized V2 thin stripe hue maps. The results indicate that neurons within the superficial layers of V2 thin stripe hue maps are organized into columns whose aggregated hue selectivity is closely related to the hue selectivity of the optically defined hue maps. These data suggest that thin stripes contain hue maps not simply because of their moderate percentage of hue-selective neurons, but because of the columnar and tangential organization of hue selectivity.

Fronto-opercular and insular cortices of Japanese macaques were histochemically stained for cytochrome oxidase activity. The laminated pattern of enzyme activity differed in the different cytoarchitectonic areas. Area G, the presumed primary gustatory area, as well as area 3 were prominent because the third stripe, corresponding to the termination layers of the specific thalamocortical projection in these areas was very dark and thick in comparison with that from the neighboring areas. This approach provides a convenient histological aid for identification of area G.

The aim of the present work was to study the distribution of cytochrome oxidase activity in the visual cortex of kittens in normal conditions. Studies were performed using computer filtration of digitized images of frontal sections. The occurrence of regularly alternating levels of enzyme activity was demonstrated in layers III, IV, and VI of field 17 and layers IV and VI in field 18.

The present study investigated whether more vicarious trial-and-error (VTE) behavior, defined by head movement from one stimulus to another at a choice point during simultaneous discriminations, led to better visual discrimination learning in a Y-maze, and whether VTE behavior was a function of the hippocampus by measuring regional brain cytochrome oxidase (C.O.) activity, an index of neuronal metabolic activity. The results showed that the more VTEs a rat made, the better the rat learned the visual discrimination. Furthermore, both learning and VTE behavior during learning were correlated to C.O. activity in the hippocampus, suggesting that the hippocampus plays a role in VTE behavior during discrimination learning.

Using cytochrome oxidase (CO) histochemistry, the effects of instrumental conditioning in cuttlefish central nervous system were examined. The posterior superior frontal lobe showed an increase of CO labelling just after training, whereas the anterior superior frontal lobe exhibited a decrease of CO staining 24 h post-training. These findings provide the first metabolic evidence for the involvement of the superior frontal lobe in learning and memory processes in cuttlefish. It is concluded that CO histochemistry can be used to provide a functional mapping of learning-induced plasticity in cuttlefish brain.

The endogenous cytochrome oxidase activity of the pigeon’s ectostriatum, the primary telencephalic structure of the tectofugal visual pathway, was histochemically demonstrated and a heterogeneous distribution of the reaction product was observed. In cross-sections the medial, central and ventrolateral parts of the ectostriatum showed high levels of activity while the centroventral and dorsolateral ectostriatum remained weakly labelled. Only slight left-right and interindividual variations were found in the pattern of labelling. These data demonstrate for the first time anatomical subdivisions within the ectostriatal core and open the possibility of functional parcellations within this structure.

The changes in cytochrome oxidase (CYO) activity in the primary somatosensory cortex (SI) induced by unilateral lesions restricted to the posterior ventrobasal region of the thalamus were investigated by histochemical techniques and photometric semi-quantitation in the rat. The CYO activity decreased rapidly and dramatically in layer IV of the lesioned side, reaching its lowest level within 2 weeks, and remained depressed at 8 weeks post-lesion. Segmentations normally seen in layer IV corresponding to barrels remained absent. While less marked decreases were also noted in other layers, obvious recovery was subsequently observed, attaining levels comparable to those on the intact size at 6 or 8 weeks post-lesion. The persistent decrease in layer IV appears to reflect a reduced thalamocortical activation of the dendritic profiles and neuronal perikarya. The recovery in other layers may represent an increase in the resting level of the initially depressed neuronal activity near to the original levels. The persistent reduction of function in the inhibitory surround, which is normally activated by thalamocortical input, may contribute to the increase in CYO activity.

Quantitative histochemistry was used to analyze changes in cytochrome oxidase (CO) activity in 93 brain regions after entorhinal cortex kindling. Rats were kindled to at least six stage-5 seizures and sacrificed either 24 h or 28 days after the last convulsion. Regional brain CO activity was quantitated in histological sections using calibrated densitometric standards. No statistically significant differences in regional CO activity between kindled and control brains were seen either 24 h or 28 days after the last convulsion. These results suggest that the brain changes underlying the kindling state are not reflected in localized alterations in mitochondrial respiratory capacity. They also indicate that long-lasting changes in regional brain CO activity recently found after electroconvulsive shock are not common to all types of seizures.

Winter- and summer-acclimatized largemouth bass (Micropterus salmoides) were collected from hatchery ponds in eastern Colorado during late winter and midsummer, then challenged with two prolonged swimming performances (step test and constant-velocity endurance). Variation in the step test performances was significantly correlated with variation in the endurance performances in the winter-acclimatized but not in the summer-acclimatized fish. Fourteen physiological and morphological traits were measured on each fish, and correlations among these traits and swimming performance were tested. None of the traits measured were correlated with performance variation in both the winter- and summer-acclimatized fish. The only significant correlate with swimming performance in the summer-acclimatized fish was white muscle lactate dehydrogenase activity (n = 19). Six of the seven factors correlating with winter swimming performance (n = 18-19) could be divided into two categories: traits associated with fasting (condition factor and liver enzymatic activity) and those associated with oxygen delivery (heart mass, heart and red muscle cytochrome oxidase activity). The results of this study suggest that morphological and physiological correlates of swimming performance in juvenile largemouth bass are profoundly influenced by seasonal variation.

In cold-acclimatized (CA) king penguin chicks exhibiting nonshivering thermogenesis (NST), protein content and cytochrome oxidase (CO) activity of tissue homogenates were measured together with protein content, CO, and respiration rates of isolated mitochondria from skeletal muscle (gastrocnemius and pectoralis) and liver. The comparison was made with chicks reared at thermoneutrality (TN) for at least 3 wk. In CA chicks showing a NST despite the lack of brown adipose tissue, an increase in thermogenic capacity was observed in skeletal muscle in which the oxidative capacity rose (+28% and +50% in gastrocnemius and pectoralis muscles, respectively), whereas no change occurred in the liver. Oxidative capacity of skeletal muscle increased together with the development of mitochondrial inner membrane plus cristae in muscles of CA chicks contrary to their TN littermates (+30 to +50%). Subsarcolemmal mitochondria of CA chicks had a higher protein content (+65% in gastrocnemius muscle) and higher oxidative capacities than in controls. The lower respiratory control ratio of these mitochondria might result from a low ADP phosphorylation rate. No change occurred in the intermyofibrillar fraction nor in liver mitochondria. These findings together with earlier results obtained in cold-acclimated ducklings indicate the marked and suited adaptation of skeletal muscle and in particular of subsarcolemmal mitochondria allowing them to play a role in NST.

Histochemical detection of cytochrome oxidase activity in chicken growth plate revealed both positively and negatively stained mitochondria in chondrocytes of all zones, i.e., proliferative, pre-hypertrophic, hypertrophic, and calcifying zones. The proportion of positive to negative cells was lowest in the proliferative zone. As cytodifferentiation progressed, more positively stained cells were present. In positive cells all mitochondria were usually stained, and in negative cells all mitochondria were unstained. A few cells appeared to be in transition and contained both types of mitochondria. The results indicate that chondrocytes utilizing both aerobic and anaerobic metabolism are present in growth plate cartilage and that oxidative metabolism is favored in the more mature cells. The relationship of oxidative metabolism to calcification is discussed.

The effects were studied of methyl isocyanate (MIC) and its thermally degraded products (dMIC) on rat brain cytochrome oxidase activity. Pure MIC did not inhibit brain cytochrome oxidase activity. A significant inhibition of brain cytochrome oxidase activity by dMIC was observed both in vivo and in vitro. The presence of cyanide in pyrolysed products of MIC has also been confirmed by chemical methods.

Polyacrylamide models in which an extract of cattle heart mitochondria was incorporated, as well as cryostat sections of tongue muscle and epithelium, were used to set up the conditions under which the histochemical reaction for the demonstration of cytochrome oxidase can be quantitated. Using diaminobenzidine in a concentration of 5.5 mM, cytochrome C in a fixed concentration of 76 micron and keeping the incubation medium away from direct light action, enzyme activity can be evaluated by means of direct microphotometry on tissue sections. Each biologic model requires previous individual determination of the measurement limits. These limits can be readily established by using a small chamber for the incubation medium, which can be placed in the microphotometer, allowing the reaction rate to be following using a single section.

was investigated in Xenopus Iaevis (the South African clawed toad) previtellogenic oocytes. Maximum activity was observed in 200 �tm oocytes. Late previtellogenic oocytes were found to have reduced cytochrome oxidase activity compared with early and midprevitellogenic oocytes. Cytomorphometry, at the electron microscope level, revealed that the number of cristae/length of mitochondrial profile remains essentially at the same level compared with the previous stages. The results are is agreement with biochemical observations and suggest that 3,3’-diaminobenzidine cytochemistry can be used successfully as a link between ultrastructural morphology and biochemistry.

The laminar distributions of cytochrome oxidase activity and vascularization of the occipital cortex of animals made micrencephalic by exposure to MAM Ac on E14 or E16 were examined and compared to control animals. Despite severe disruptions of the normal cytoarchitecture in MAM Ac exposed animals, the laminar distributions of vascular profiles, branch points and cytochrome oxidase activity in micrencephalic animals were similar to those in control animals.

Cytochrome oxidase histochemistry revealed patchy patterns of the enzyme activity in transverse sections through the caudal part of the ventral subnucleus of the principal sensory trigeminal nucleus, interpolar spinal trigeminal nucleus, and layer IV of the caudal spinal trigeminal nucleus in the cat. By the transganglionic transport method of horseradish peroxidase, the patterns were indicated to replicate the spatial array of the facial vibrissae.

Cytochrome oxidase activity has been assessed by a method of kinetic microdensitometry which involves applying tissue sections to gel films containing phenylamine substrates and measuring the rate of azine dye production by continuously recording the rate of change in extinction. Optimum conditions for the technique were defined, and the results compared with those obtained by conventional end-point microdensitometry in which sections are incubated in histochemical substrate solutions and azine dye production estimated by a single measurement of extinction at the end of the incubation period. When compared with biochemically-determined enzyme activity, kinetic microdensitometry gave a better index of the proportionate activity of cytochrome oxidase in various normal tissues than did end-point microdensitometry. In addition, the degree of inhibition of cytochrome oxidase activity in tissues removed from cyanide-poisoned animals was assessed more reliably by kinetic microdensitometry than by end-point measurements. With end-point microdensitometry, the reaction is non-linear over the comparatively long incubation times required and there is also a spontaneous reactivation of cyanide-inhibited cytochrome oxidase during incubation and thus a progressively increased rate of substrate utilization. In contrast, with kinetic microdensitometry the initial linear reaction rate is measured before significant reactivation occurs. Kinetic microdensitometry can be used for direct dynamic quantitation of enzyme activity in tissues or cells; it may be a valuable technique for quantitative histochemical confirmation or extension of biochemical studies; and it appears to be a reliable direct quantitative histochemical method for investigating in vivo inhibition of enzyme activity, where spontaneous reactivation of the enzyme-inhibitor complex may occur.

The identification of different anatomical regions of the periaqueductal gray matter of rats was addressed in the present study by using the histochemical staining for the mitochondrial enzyme cytochrome oxidase. At caudal and middle levels, cytochrome oxidase histochemistry clearly demonstrates the existence of four subdivisions: dorsal, dorsolateral, ventrolateral and medial, whereas in sections from the rostral periaqueductal gray matter only two concentric bands are identifiable on the basis of the degree of cytochrome oxidase activity.

Lesions were found in the pancreas of clinically normal cattle of low copper status. In comparison with the pancreas of cattle with normal hepatic copper reserves, the abnormalities were an increase in the dry matter content and reduction in the concentrations of protein and copper in the wet tissue. Cytochrome oxidase activity and protein-to-RNA ratio were also reduced. Histologically, there were defects in acinar basement membranes, splitting and disorganization of acini, cellular atrophy and dissociation, and stromal proliferation. The pancreatic ductular system did not show atrophy or disorganization.

Cytochrome oxidase, succinic dehydrogenase, and succinate oxidation were studied in the anterior, middle, and posterior hypothalamus during the sexual cycle in normal female rats as well as in rats re

Rat heart muscle was spectrophotometrically assayed for succinic dehydrogenase and cytochrome oxidase activity to determine the extent of cryoprotection afforded by DMSO-glycerol solutions. Activities of these two enzymes were greater in the frozen untreated heart than in the normal heart. It was also found that the cryoprotectant without freezing tended to increase the activity of succinic dehydrogenase while cytochrome oxidase activity decreased.

Prolonged isoproterenol administration increases the monoamine oxidase (MAO) but not the cytochrome oxidase activity of rat salivary glands. This increase in MAO can be blocked by prior administration of propranolol or actinomycin D, but is not diminished by ganglionectomy or duct ligation. Three hours after isoproterenol an increase in MAO activity is detectable, but is not significantly inhibited by propranolol. No increase in cardiac MAO concentration was observed. It is suggested that the increased MAO activity may be related to increased enzyme protein in the stimulated secretory cells.

Summary Using the DAB method, cytochrome oxidase activity could be detected in isolated rat thymus nuclei, confined both to membranes of the nuclear envelope and intranuclearly in the euchromatic regions, mostly in the form of granules and sometimes of bodies. Detergent-treated nuclei show the intranuclear deposits almost exclusively.

Groups of animals were treated with injections of isopropylnoradrenaline, thyroxine, or both hormones together. The effects of these hormonal treatments on the size, protein content, and level of some mitochondrial enzymes, in particular the cytochrome oxidase, were determined and compared to the effect on these parameters produced by cold adaptation. The changes observed were correlated with the resistance of the animals to cold stress and with their metabolic response to injections of isopropylnoradrenaline. All treatments increased the size of the brown adipose tissue. Whereas thyroxine had little effect on the protein content and cytochrome oxidase, both isopropylnoradrenaline and cold adaptation produced increases in these parameters. It appears that the isopropylnoradrenaline-treated animals mimic more closely the cold-adapted animals than do those with thyroxine treatment. However, the isopropylnoradrenaline-treated animals are not as resistant to cold as the cold-adapted animals.

After having schematically drawn attention to the distribution of cyto-chrome oxidase in the cochlea of the normal guinea-pig (described in a former work) and the principal data of the literature relating to the histoche-mical and biochemical variations shown in the inner ear subsequent to sound stimulation, the authors describe the method of the investigation and its results. Intense sound stimulation (100 decibels) with pure tones of diverse frequencies (250, 2000, 4000, 8000 Hz), for a period of 3 hours, brings about a histochemically demonstrable reduction of enzymatic activity; this reduction is diffuse, does not depend on the frequency used, and is apparent not only at the level of the organ of Corti but also, more especially, at the site of the stria vascularis and the external spiral sulcus. These results are then briefly commented upon.

SummaryDay-old turkey poults were fed 5 levels of supplemental copper for 6 weeks. There was a significant stimulation of growth in those fed 1.32 to 3.96 ppm of added copper. Microhematocrits of all turkeys were within normal ranges. The erythrocytes of birds fed 1.32 ppm of supplemental copper had abnormally shaped nuclei, while those of poults fed 1.98 and 3.96 ppm of copper were normal. Nuclear changes consisted of lobulated nuclei, duplication of nuclei, forked nuclei and other bizarre manifestations. Heart and liver cytochrome oxidase activity was greater in those birds fed 1.32 to 3.96 ppm of added copper.

The cytochrome oxidase activity of isolated mitochondria of unfertilized and fertilized eggs of Paracentrotus lividus has been studied. It has been found that whereas in the mitochondria of unfertilized eggs saturation is reached at a cytochrome c concentration of 3.28 × 10−5 M, in those of fertilized eggs this occurs at a concentration of 5.74 × 10−5 M. It is shown that upon fertilization an increase of about 30 per cent of the activity of cytochrome oxidase takes place and no further changes appear to occur until blastula stage.

Study of the relationship of cytochrome oxidase activity of certain tissues to the body weight has been extended to include three species of large animals. In the comparison of rats, sheep, swine and cattle, the cytochrome oxidase activity of skeletal muscle (principally of the gracilis) was found to be roughly an inverse function of body weight. A logarithmic regression of –0.239 was calculated. Although the cytochrome oxidase activity per unit weight of liver in the sheep, swine and cattle series does not reflect the variation in body mass, the regression of the logarithm of total liver cytochrome oxidase activity on the logarithm of body weight was calculated to be 0.674. The data support the concept that the summated total measurable cytochrome oxidase activity is very nearly proportional to body weight to the 3/4 power and, hence, to basal metabolism.

The cytochrome oxidase activity of skin and gingival homogenates was found to be very labile upon standing at 0° C. The enzymatic activity was stabilized for 1–4 hours in the presence of (1–2)% Ficoll, (1–2)% DMSO, or 1% combinations of Ficoll and DMSO in a phosphate-buffered system. These agents were found to be ineffective as stabilizers in the presence of Tris-maleate buffer. The specific activity values of stabilized homogenates declined towards those of the non-stabilized controls alter the stabilizing effect was dissipated.

Cytochrome oxidase activity was evaluated histochemically as an index of mitochondrial damage after local irradiation with X-rays. It was determined by microphotometry on the tail skin of newly born Wistar rats four days after irradiation with doses ranging from 2 to 16 krad. The enzyme activity of the whole epidermis increased after irradiation, the increases being related to the increase in thickness of the epithelium which was observed as a response to irradiation injury. Within the dose range tested, the enzyme concentration (expressed per uni volume of tissue) decreased in relation to the dose applied. At the electron microscopy level, the cytochemical demonstration of cytochrome oxidase revealed an irregular reaction over the cristae, intramitochondrial vacuolization and partial homogenization of the matrix. Positive membrane fragments were seen around lipid droplets. This reaction confirms the mitochondrial origin of these previously observed radiation-induced vacuoles.

1. A small lesion was placed in the rat somatosensory vibrissa cortex on postnatal days (PND) 0, 5, 10, 14 or 20. At the age of three months, the animals were sacrificed and tangential sections of the somatosensory cortex were reacted for detection of succinic dehydrogenase or cytochrome oxidase activity to see if the lesion had produced a defect in the barrelfield. 2. In animals of the groups of PND 0, 5 and 10, the entire barrelfield formed normally, but avoided the lesioned cortex. In a few cases, however, the lesion was found between rows of barrels but never between arcs of barrels. This latter type of result was seen only in the PND-0 group. 3. In animals of the groups of PND 14 and 20, the lesion typically resulted in a defect in the barrelfield. 4. It is concluded that the vibrissa cortex attains its final topographic specificity between day 10 and day 14 postnatally. In view of the date of barrelfield formation in normal animals (postnatal day 5), it is thought that the barrelfield is subject to plastic reorganization for some days after its formation; at least for the period between postnatal days 5 and 10.

The laminar location of cytochrome oxidase staining has been compared in the lateral geniculate nucleus and area 17 in newborn and adult macaque monkeys. In area 17 of the adult, the distribution of cytochrome oxidase activity confirmed published findings. In the newborn animals, the tissue reacted as strongly for cytochrome oxidase as in the adult but the pattern of labelling was different in two respects. Firstly in layer 1 activity was stronger and occupied a wider portion of this layer. Secondly, cytochrome oxidase staining in layer 4C occupied two separate bands, a small narrow band at the bottom of 4C beta and a wider one occupying the full width of 4C alpha and spilling over into 4B. The pattern of cytochrome oxidase activity did not appear to be influenced by eccentricity in the newborn whereas, in the adult, label in 4C was more intense in cortex subserving central vision. In the lateral geniculate nucleus of the adult, the magnocellular layers and the most dorsal parvocellular layer reacted most strongly for cytochrome oxidase. In the newborn, parvocellular layers were more uniformly labelled and the difference between parvo- and magnocellular layers more pronounced. These results are discussed in relationship to the development of thalamo-cortical projections in the monkey.

The laminar pattern of cytochrome oxidase activity was studied in visual cortical areas 17, 18 and 19 in adult cats and kittens, following electrophysiological determination of the boundaries of these areas in all but the youngest animals. The patterns of cytochrome oxidase staining and the cytoarchitectonic appearances of areas 17, 18 and 19 were compared. At all ages activity was especially high in the region of layers IV and VI in areas 17 and 18, and was low in all laminae in area 19. The results suggest that the degree of cytochrome oxidase activity in these regions of the visual cortex may be related to the strength and type of projection that they receive from the lateral geniculate nucleus. The cytochrome oxidase technique is a useful means of defining the 18/19 border, and may help locate the boundary between areas 17 and 18, in both adult cats and kittens.

Patterns of cortical connections were studied in brain sections cut parallel to the surface of mechanically flattened cortex after single, double, or multiple injections of wheatgerm agglutinin conjugated to horseradish peroxidase (WGA-HRP) in area 17 of galagos ( Galago crassicaudatus ). Intrinsic connections of area 17 included a systematic pattern of patches of labeled cells and terminations associated with blobs of high cytochrome oxidase activity. The patches of connections extended with decreasing density for a distance of 2 mm or more from the margins of injection sites. Injections also revealed dense interconnections with area 18 (V-II) and the middle temporal visual area (MT). Single injections in area 17 produced several foci of label in both area 18 and MT, suggesting that a given location in area 17 is interconnected with subsets of processing modules in both of these fields. Injections including dorsolateral area 17 also labeled cortex between area 18 and MT. Finally, most injections in area 17 produced small foci of sparse label just lateral to MT in the temporal lobe.

Histochemical densitometric measurements of cytochrome oxidase (CO) activity in the dorsal and ventral lateral geniculate nuclei (LGNd and LGNv) and the superficial gray stratum of the superior colliculus (SC) were done between 2 and 12 weeks after unilateral enucleation in the adult albino rat. This deafferentation resulted in a transient, slight but statistically significant decrease in CO activity in the contralateral LGNd and LGNv. Whereas in the contralateral SC, a marked reduction in CO activity was observed, and this persisted over the postoperative periods studied. The regional difference in the recovery pattern of CO activity were discussed from the aspect of synaptic reorganization.

Methylprednisolone injected intraperitoneally in rats (pharmacological doses) during a short time (1–2 days) interval activated gingival cytochrome oxidase activity at drug treated sham, and drug treated wound and distal (contralateral) non-injured sites. Gingival cytochrome oxidase was activated in drug treated sham and injured gingiva between the 5th and 7th days after drug (2 doses) initiation. Enzymatic activities in both groups declined between the 7th and 10th days toward control levels. An increase in enzymatic activity occurred within 1 day at the distal (non-injured) contralateral site in animals which received only one dose of methylprednisolone. The enzymatic activity declined between the 1st and 2nd day to control values and remained at that level for the duration of the experiment.