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The ip and iv LD50 values of 1145 and 855 mg/kg of clindamycin 2-phosphate in the Swiss white mouse were approximately 3 times higher than those of clindamycin hydrochloride. The lesion produced by single injection of 50 or 100 mg/ml of clindamycin 2-phosphate in the loin muscles of the New Zealand White rabbit was graded as slight. The 24-hr serum creatine phosphokinase value was 1500 IU/liter which was less than one-half that of the parent antibiotic. Body weight gains and food conversion ratios in groups of 10 Sprague-Dawley rats injected sc with 120 mg/kg for 6 days were comparable to those of the control group; 90 mg/kg was tolerated in these terms nearly as well for 30 days as no treatment or doses of 30 and 60 mg/kg. From 22 to 33 injections (each equivalent to 30, 60 or 90 mg/kg) were made bilaterally in the posterior thigh muscles of groups of 3 beagle dogs. The terminal elevations of serum glutamic-oxaloacetic transaminase varied from 54 to 400 Reitman-Frankel units. The characteristic pathologic change resulting from the superimposed injections was dose-related progressive scarring of the muscle bundles. Intravenous administration of 60 and 120 mg/kg daily in divided doses in 2 groups of 4 dogs each for 30 days produced no detectable irritation in the peripheral veins or drug-related hemolysis. Tests for drug-induced hemolysis and changes in erythrocyte fragility by in vitro methods were negative. In dogs treated iv with 120 mg/kg for 1 week, as light increase in neutral lipid droplets was present in hepatocytes from 3 hr to 3 days when examined by electron microscopy. This transient change was not observed in dogs injected im with 90 mg/kg for the same period.

A sensitive and specific radioimmunoassay for TRH is reported. Antibody was raised in a New Zealand white rabbit by immunization with TRH complexed to bovine thyroglobulin through bis-diazotized benzidine. The assay was capable of detecting below 7 pg of TRH in biological materials. Immunoreactive TRH was found in hypothalamic extracts from man, pig, rat, hamster, chicken, frog, snake, salmon, and in whole brain of the larval form of the primitive cyclostome lamprey, and in the head region of the protochordate amphioxus. The TRH levels in the frog hypothalamus were 1520–3620 pg/mg tissue, being 6–12 times the concentration detected in the rat hypothalamus. These findings indicate that TRH is distributed throughout the vertebrate kingdom, and has an ancient lineage. Immunoreactive (IR) TRH up to 764 pg/mg tissue was found in brain regions, other than hypothalamus, of the lower vertebrates, snake, frog, tadpole and salmon. Small but significant concentrations were also found in extrahypothalamic brain of th...

The present interest in malformations of the rabbit stems almost entirely from a chain of events that originated in the thalidomide disaster and expanded through a multiplicity of animal studies which, among other things, demonstrated that thalidomide consistently causes malformations in the rabbit embryo. Culmination of the chain was the acceptance of the rabbit as a suitable species for teratogenicity screening tests in the safety evaluation of new drugs (Table 1). It is now evident that, for drug evaluation studies, susceptibility of the test species to thalidomide is a somewhat doubtful recommendation. Thalidomide is unique and atypical so that a positive result obtained with it is not necessarily indicative that a species will be susceptible to teratogens that depend on quite different modes of action. Fortunately the rabbit (especiaIly the New Zealand White) possesses a number of basic characteristics that are an asset in teratology studies. Some of these characteristics, and the advantages that spring from them, are: domesticated and of moderate size (foetus 40 g, adult 3-4 kg)~easily visible defects, moderate drug need, ease of handling and maintenance, short gestation (32 days); prolonged oestrus and induced ovulation~pregnancy easily and accurately timed, artificial insemination possible

25 mature New Zealand white rabbit does (weighing between 3500 and 4500 grams) were used in an investigation to determine whether resection of the uterotubal junction (UTJ) alters the postovulatory functional blocking mechanism which keeps newly fertilized ova in the oviduct from 72-96 hours. A unilateral resection of the UTJ was performed in each animal. 2 of the 25 rabbits died 1-3 days following the anastomosis. 2 other rabbits refused the male although isolated on 2 occasions for a period of 21 days. In these 2 rabbits laparotomy disclosed a paucity of follicles in either ovary; no corpora lutea or adhesions were found and the anastomosis was patent. 10 additional rabbits failed to have pregnancies in either side despite many corpora lutea present in their ovaries. Many adhesions had formed in these 10 animals immobilizing their oviducts. Dissection of these adhesions around the oviducts revealed that the fallopian tubes were not distended with accumulated fluid and the anastomosed area was patent. 11 of the rabbits were pregnant on both sides. 8 of these animals were in good condition. In 2 there were fine adhesions between omentum and bladder and between intestines. In all instances the oviducts and uterine horns were free and mobile. A good correlation between the number of corpora lutea and the number of implantations of the control side was found.

Swapan 11.6568 Normal 0 false false false MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} Crossbred New Zealand White meat type 8 male and 16 female rabbits aged 3.5 to 4.5 months weighing 9.5 to 13.0 kg were used in a 128 day trial to study the effects of concentrate supplementation on growth and reproductive performance of rabbit under rural condition. Rabbits were divided according to live weight into two treatment groups, i.e. T 1 (conventional diet) and T 2 (conventional diet + concentrate 75 g/d per rabbit) with four replications per treatment in a Complete Randomized Design (CRD). All animals had free access to locally available green grasses. Results showed that, average daily live weight gain was significantly (p 2 (13.02 ± 0.43 g/d) than T 1 (5.30 ± 0.43 g/d) group. Litter weight at birth was better (p < 0.05) in T 2 (180.38 ± 16.37g) than T 1 (137.19 ± 16.37g) group. Litter size at weaning differed (p < 0.05) and the mean values were 1.37 ± 0.30 for T 1 and 2.37 ± 0.27 for T 2 group. Kit weight at weaning was superior (p 2 (408.12 ± 3.85g) than T 1 (310.62  ± 3.56g) group. Kit mortality up to weaning was higher (p 1 (45.0 ± 10.07 %) than T 2 (26.92 ± 10.7 %) group. These results indicate that, supplementation of concentrate in addition to conventional feeding may improve growth and reproductive performance of rabbit under rural condition. Key words: Crossbred, New Zealand White rabbit, reproductive performance, growth, concentrate DOI = 10.3329/bjvm.v4i2.1296 Bangl. J. Vet. Med. (2006). 4 (2): 129-132

Carbonic anhydrase activity was localized histochemically in the retinas of five species: turtle (Pseudemys scripta), toad (Bufo marinus), New Zealand white rabbit, Sprague-Dawley albino rat, and human. By light microscopy, activity was present in Muller cells of all species and in pigment epithelium of the turtle, rat, and rabbit. In the human, the only mammal studied with numerous cones, the cones, but not the rods, displayed carbonic anhydrase activity. By electron microscopy, the reaction product was a finely granular precipitate, localized to the Muller cell cytoplasm and the cytoplasm associated with the pigment epithelial basilar infoldings and apical villous projections. Depending on the species studied, the histochemical reaction was completely inhibited by acetazolamide at concentrations of 0·5−5 × 10−6 m in the incubation medium. The mean carbonic anhydrase activities of the rabbit and turtle retinas were biochemically quantitated to be 991 units and 504 units/g dry weight, respectively, and 8·9−10·3% of the original activity was retained after fixing for 2 hr in 3%, 0·17 m cacodylate-buffered glutaraldehyde.

This study was carried out to determine the effects of denervation of the pulp organs of teeth, particularly on the odontoblasts and their processes. Therefore, resection of the inferior alveolar, cervical sympathetic, or a combination of both types of nerves supplying the mandibular incisor teeth of New Zealand white rabbits was performed and the results compared to adjacent, unaltered teeth. Neural stains were used to evaluate the presence or absence of nerve elements, while histochemical and titrametric methods were employed to determine the presence, location and concentration of cholinesterase enzymes in these teeth. Dilation of blood vessels was noted after cervical sympathetic resection and larger nerve trunks as well as peripherally located fine fibers were absent in the pulps following inferior alveolar nerve resection. Further, irregular dentin formation and associated small openings in the tips of the teeth were observed after nerve resection. Titrametric analysis indicated a significant decrease in the concentration of cholinesterase in the pulp organ of incisors 15–19 days after resection of either the inferior alveolar nerve or both inferior alveolar and cervical sympathetic nerves. Only a slight decrease in the concentration of cholinesterase was noted after removal of the cervical sympathetic nerve alone. Histochemical results confirmed a decrease in cholinesterase after resection of the inferior alveolar, cervical sympathetic or both nerves. The concentration of the oxidative enzyme, succinic dehydrogenase, however, increased after all three types of nerve resection. This increase was apparent particularly in the odontoblastic cells underlying the predentin.

The effect of chlormadinone acetate (CA) on mammary growth and lactation was studied in the New Zealand white rabbit. Mammary development studies were performed in 5-month males castrated prepuberally. All rabbits were treated for 28 days. Ten μg estrone (E) produced good ductal development without alveolar growth (mean mammary area = 376 mm2). CA alone did not stimulate mammary growth. Administration of 0.5 mg CA plus 10 Mg E produced optimal ductal and alveolar development (mean mammary area = 765 mm2). By contrast, a larger dose of CA (2.5 mg) combined with 10 μg E resulted in a much smaller mammary response (mean mammary area = 284 mm2). Administration of 100 ng or 2.5 mg CA from day 10 to 25 of lactation neither inhibited nor facilitated milk production in lactating rabbits. It is concluded that prolonged administration of CA when combined with estrogen stimulates mammary growth at moderate doses (0.5 mg) and inhibits it at large doses (2.5 mg). CA has no clear effect on milk production and/or remova...

Summary1. Methods of concentrating soluble proteins are reported for aqueous extracts of cornea. These methods apparently do not denature the proteins. 2. These methods were applied to increase concentration of protein from aqueous extracts of bovine, swine, New Zealand White rabbit and mongrel rabbit corneas to a level which would permit ultracentrifugal analysis of these extracts. 3. Fundamental differences in number of protein fractions and particle size distribution were noted in these extracts. This suggests a species difference in soluble corneal proteins. 4. Differences were noted in sedimentation diagrams of extracts from New Zealand White rabbits and mongrel rabbits, suggesting differences in soluble corneal protein content of different strains of the same species.The authors wish to thank Lt. Col. L. J. Milch of the School of Aviation Medicine, Randolph Field, Texas for valuable advice and evaluation of this work.

Seventy-two female New Zealand white rabbits were divided into six groups and killed with Nembutal at 17.0, 17.5, 18.0, 18.5, 19.0 and 19.5 days postconception. The foetuses were removed; the palates, maxilla, mandibles and tongues were dissected from each foetus, weighed and pooled; DNA, RNA and protein were determined in each pooled sample. The results showed three distinct patterns of development. The mandible and maxilla showed similar developmental patterns, while the palate and tongue each showed their own distinct pattern. The palate showed a remarkable rise in protein/DNA at day 18.0, the time corresponding to palatal closure in our rabbits. Further such studies may elucidate the role that relative growth rates of these tissues plays in the aetiology of cleft palate.

1. The fate in the pregnant New Zealand White rabbit of oral doses of four (14)C-labelled hydrolysis products of thalidomide, namely alpha-(o-carboxybenzamido)-glutarimide, 2-phthalimidoglutaramic acid, 2-phthalimidoglutaric acid and 2-(o-carboxybenzamido)glutaramic acid, administered on the 192nd hour of pregnancy has been studied. 2. About 60-95% of the administered (14)C of each compound appears in the urine in 58hr. and the remainder is found in the faeces and in the gut and its contents. 3. Radioactivity is present in the plasma, liver, kidney, brain, muscle, fat and embryo. 4. The (14)C-labelled substances in the plasma and embryo consist of the unchanged compounds and their further hydrolysis products. 5. Since the above four thalidomide hydrolysis products are found in the rabbit conceptus together with their further hydrolysis products after their oral administration to the pregnant rabbit, it appears that the teratogenic activity of thalidomide is due to the compound itself rather than to one or more of its hydrolysis products.

1. Susceptibility to dietary induction of hypercholesterolaemia and aortic atherosis was compared in two groups of male New Zealand White rabbits. 2. Twelve rabbits were purchased from one breeding establishment (group I) and twelve from another (group 2). On arrival at the laboratory six animals from each group were killed and the aortas were removed. Blood samples were taken from the remaining twelve animals and then they were givenad lib.for a period of 40 weeks an atherogenic diet containing 20% butterfat. During this period food intake and body-weight were recorded. At the end of the period blood samples were taken from the animals and immediately afterwards they were killed and the aortas were removed. 3. No atheromatous lesions were found in the aortas of the rabbits in either group killed at the beginning of the experiment. There were no differences between the two groups of animals with respect to body-weight or concentration of cholesterol in the plasma at the beginning of the experiment, food intake during the experiment or body-weight at the end of the experiment. At the end of the experiment, the degree of aortic atherosis in the rabbits of group I was considerably greater than that in the rabbits of group 2. 4. At the end of the experiment the concentrations of total lipids, free cholesterol, esterified cholesterol and phospholipids in the plasma of the rabbits in group 1 were significantly higher than the corresponding concentrations of these lipid components in the plasma of the rabbits in group 2. The concentrations of palmitic, stearic and linoleic acids in the cholesterol esters and the concentration of palmitic acid in the unesterified fatty acids in the plasma of the rabbits in group 2 were significantly higher than the corresponding concentrations of these fatty acids in the plasma cholesterol esters and unesterified fatty acids in the rabbits of group 1. 5. It is concluded that these differences in response to the atherogenic diet were reflections of the differences in the susceptibilities to the dietary induction of hypercholesterolaemia and atherosis of the two differents strain of rabbit that had been established by the two commercial breeders. Such differences in susceptibility could readily explain certain discrepancies in the results of various research workers engaged in this field of investigation.

The influence of pentobarbital anesthesia, laparotomy, and uterine horn atmospheric exposure on survival and normal development of New Zealand White rabbit fetuses has been determined. Anesthesia and surgery were accomplished on the 7th, 8th, 9th, and 10th postcoital days. Atmospheric exposure times of 0, 5, 10, and 15 min were used. Neither pentobarbital anesthesia nor laparotomy with atmospheric exposure of the uterine horns significantly affected the spontaneous incidence of malformed fetuses in the rabbit colony. However, anesthesia and the surgical trauma of laparotomy increased the incidence of early death and resorptions. Older fetuses were more vulnerable to damage from the anesthetic procedure but less vulnerable to damage from the surgical trauma of laparotomy. Atmospheric exposure per se did not appear to influence the incidence of resorptions.

Summary A total of 3935 New Zealand White rabbits' foetuses obtained on day 29 of gestation from 521 does was examined for abnormalities of external form and/or skeleton. Some 35 young were classified as abnormal within this context and are described. Attention is drawn to a naturally-occurring variation in the normal morphology and also to a variation due to immaturity.

THE thalidomide molecule contains an asymmetric carbon atom, but the form of the drug which has been used therapeutically and which has produced congenital malformations in man is the optically inactive form, that is (±)-thalidomide. The optical antipodes of thalidomide have been synthesized1,2, and Dr A. M. Creighton has supplied samples of both (+)- and (−)-thalidomide. The (+)-isomer, melting point 240°–241° C, showed [α]D20+60° (c = 2 in dimethylformamide) and the (−)-isomer, melting point 241°–242° C; showed [α]D20−58° (c = 2 in dimethylformamide). (±)-Thalidomide has a melting point of 271° C and, of course, is optically inactive. With these samples, we have determined the acute oral toxicities of the three forms in mice, their teratogenic activity in the New Zealand white rabbit and their effect on the hypnosis induced by hexobarbitone in mice.

Rhodium trichloride was found to be a substance of low toxicity when administered to rats and rabbits. The LD50 for rhodium trichloride administered by a single iv injection to the adult male Sprague-Dawley rat was 198 mg/kg (184–212) and to the adult male New Zealand white rabbit was 215 mg/kg (138–336). Histopathological studies involving the major organs of rats and rabbits revealed no pathological changes.