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Competing Interests: The authors declare no conflicts of interest.

Background: Simulation-based medical education has been used in medical training for decades. Rapid cycle deliberate practice (RCDP) is a novel simulation strategy that uses iterative practice and feedback to achieve skill mastery. To date, there has been minimal evaluation of RCDP vs standard immersive simulation (IS) for the teaching of cardiopulmonary resuscitation to graduate medical education (GME) learners. Our primary objective was to compare the time to performance of Advanced Cardiac Life Support (ACLS) actions between trainees who completed RCDP vs IS., Methods: This study was a prospective, randomized, controlled curriculum evaluation. A total of 55 postgraduate year-1 internal medicine and emergency medicine residents participated in the study. Residents were randomized to instruction by RCDP (28) or IS (27). Stress and ability were self-assessed before and after training using an anonymous survey that incorporated five-point Likert-type questions. We measured and compared times to initiate critical ACLS actions between the two groups during a subsequent IS., Results: Prior learner experience between RCDP and IS groups was similar. Times to completion of the first pulse check, chest compression initiation, backboard placement, pad placement, initial rhythm analysis, first defibrillation, epinephrine administration, and antiarrhythmic administration were similar between RCDP and IS groups. However, RCDP groups took less time to complete the pulse check between compression cycles (6.2 vs 14.2 seconds, P  = 0.01). Following training, learners in the RCDP and IS groups scored their ability to lead and their levels of anticipated stress similarly (3.43 vs 3.30, ( P  = 0.77), 2.43 vs. 2.41, P  = 0.98, respectively). However, RCDP groups rated their ability to participate in resuscitation more highly (4.50 vs 3.96, P  = 0.01). The RCDP groups also reported their realized stress of participating in the event as lower than that of the IS groups (2.36 vs 2.85, P  = 0.01)., Conclusion: Rapid cycle deliberate practice learners demonstrated a shorter pulse check duration, reported lower stress levels associated with their experience, and rated their ability to participate in ACLS care more highly than their IS-trained peers. Our results support further investigation of RCDP in other simulation settings., Competing Interests: Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare.

Introduction: Survival from traumatic cardiopulmonary arrest (TCA) has been reported at a rate as low as 0-2.6% in the civilian pre-hospital setting, and many consider resuscitation of this group to be futile. The aim of this investigation was to describe patients who received cardiac massage during TCA in a battlefield setting; we also aimed to identify predictors of survival., Methods: We conducted a review of the Department of Defense Trauma Registry to identify patients who received cardiac massage in the battlefield between 2007 and 2014. Patients were also grouped according to location of cardiac arrest: pre-hospital (PH) and in-hospital (IH). The groups were compared and evaluated by injury, transport time, type of resuscitation, and pre-hospital procedures. Outcome variables included survival to discharge and 30-day survival. Categorical variables were analysed using chi-square or Fisher's exact tests. Wilcoxon tests were performed for continuous variables. Regression modelling was used to assess for predictors of survival., Results: 75 of all 582 patients (13%, 95% CI 10-16) survived to 30 days, and all survivors were transported out of the battlefield; 23 PH (7.8%, 95% CI 5.2-12) and 52 IH (17%, 95% CI 13-22) patients survived to 30 days (p < 0.001). Closed-chest cardiac massage with the administration of intravenous medications was associated with 30-day survival among IH patients., Conclusions: We report a 13% survival to 30 days among all patients receiving cardiac massage in a battlefield setting. Closed-chest cardiac massage predicted survival among IH TCA victims who also received intravenous medications in this review of combat-related TCA., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A technique for replacement of a feeding jejunostomy tube using endoscopic direct visualization is described herein. It can be used in patients who have had a previously placed open jejunostomy tube removed after recovery from resection of the gastrointestinal tract. This is accomplished quite easily using local anesthesia with intravenous sedation using an upper endoscope, guide wire, peel-away sheath and a standard Silastic catheter.

Background: Current noninvasive evaluation techniques of thyroid nodules are nonspecific. We studied the use of a new noninvasive imaging modality, positron emission tomography (PET), in the evaluation of thyroid nodules., Methods: Nineteen patients were studied before operation with PET with [18F]-2-deoxy-2-fluoro-D-glucose (FDG). Twelve patients had solitary thyroid nodules and seven had multinodular goiters. Fourteen overlapping transverse slices were acquired through the thyroid gland. A region of interest was drawn around the abnormal area and the maximum pixel value was calculated and corrected to produce a normalized value for FDG uptake., Results: Four of the 12 nodules were malignant (three papillary and one follicular carcinoma), with the others being follicular adenomas. All of the multinodular goiters were benign. All of the malignancies had an FDG greater than 8.5 and all of the benign nodules had an FDG less than 7.6. The dose uptake ratio of FDG was 10.8 +/- 3.2 (mean +/- SD) for the malignancies and was significantly greater than the dose uptake ratio of either the follicular adenomas (4.3 +/- 2.0) or the dominant nodule in multinodular goiters (3.0 +/- 2.0)., Conclusions: The FDG uptake as measured by PET scanning successfully discriminated between all benign and malignant tumors. This technique appears useful in the evaluation of thyroid nodules.

Nine patients with suspicious thyroid nodules were studied with positron emission tomography (PET) following the administration of [18F]-2-deoxy-2-fluoro-D-glucose (FDG) prior to surgical excision. Three patients were ultimately determined to have papillary carcinoma, four were shown to have follicular adenomas, and two were proven to have multinodular goiters with dominant nodules. All three malignancies and four of the six benign lesions were easily detected visually as areas of increased FDG uptake. While visual analysis alone did not discriminate between the benign and malignant lesions, all three malignancies had dose uptake ratios (DURs) for FDG in excess of 8.5 while the DURs for benign lesions ranged between 1.9 and 6.3. The mean FDG DUR for the three papillary carcinomas (10.9 +/- 3.9; mean +/- SD) was significantly greater (p = 0.0019) than that of the six benign lesions (3.2 +/- 1.7). There was no significant difference between the FDG DUR for the follicular adenomas and the dominant nodules of multinodular goiters. Further research is needed to confirm the usefulness of PET in the differential diagnosis of thyroid nodules, and, in particular, whether or not PET can discriminate between benign and malignant follicular neoplasms.

The management of gallstones in diabetic patients has traditionally been considered problematic. Autopsy findings and uncontrolled studies have documented a higher prevalence of cholelithiasis in diabetics, and early reports showed dramatically increased perioperative morbidity and mortality for treatment of diabetics with acute cholecystitis. As a result, some authorities have recommended prophylactic cholecystectomy for diabetic patients with asymptomatic gallstones, which is in contrast to recommendations for nondiabetics. More recent investigators have shown comparable rates of operative morbidity and mortality for biliary surgery in diabetics when compared with the general population. Recent studies have questioned whether diabetes is an independent risk factor for gallstone formation. Decision analyses using these new data have shown that prophylactic cholecystectomy is not of clear benefit and should not be routinely recommended for diabetics with asymptomatic gallstones. We believe that available data, although limited, indicate that asymptomatic patients with diabetes do not benefit from screening for gallstones and that cholecystectomy should only be performed in cases of symptomatic cholelithiasis, as is the case in the general population.

Rectal bleeding is a frequent presenting symptom of a number of benign anorectal disorders. However, it may also be a warning sign of more significant gastrointestinal pathology. For this reason, full colonic evaluation has been recommended in patients with intermittent bright red rectal bleeding. The purpose of this study is to evaluate the utility of colonoscopy in this setting. Data were prospectively collected on 125 colonoscopies performed on the surgical service at the Cleveland Wade Park Veterans Administration Medical Center during a two year period. During this period 33 patients underwent colonoscopy for the evaluation of intermittent bright red rectal bleeding. Fourteen patients had abnormal rectal exams, including hemorrhoids in 9, mass lesions in 3, prolapse in 1, and fistula in ano in 1. Colonoscopy was normal in only 7 (21%) of the 33 patients examined. Findings in the remaining 26 included 31 polyps in 14 patients, cancer in 3, AVM in 1, diverticula in 9, hemorrhoids in 4, and other benign lesions in 5. Positive findings on rectal examination had no relationship to findings at endoscopy, with abnormal findings in 52% of patients with normal rectal exams and in 27% of patients with abnormal rectal exams (P = 0.187, NS). Findings at colonoscopy resulted in a change in management in 16 (48%) of patients examined. In patients with intermittent rectal bleeding, the entire colon should be evaluated regardless of findings on rectal examination, as a significant number of patients will have concomitant findings. Colonoscopy is an excellent method for colonic evaluation in this setting.(ABSTRACT TRUNCATED AT 250 WORDS)

Standard therapy of enterocutaneous (ECF) and colocutaneous (CCF) fistulas consists of "conservative" management, with surgery reserved for failures of maximal medical treatment. We conducted a five-year retrospective review of 28 patients with low-output ECF and CCF to determine the outcome of early surgical and nonsurgical treatment of these conditions. Twelve men and 16 women with a mean age of 60 years presented with 22 ECF and 6 CCF. Six patients had early operative intervention in an attempt to close their fistulas, while the remaining 22 patients were treated without surgery. In addition, four of the nonsurgical group received parenteral somatostatin analog (SA). None of the surgical patients was septic preoperatively (mean WBC = 9.7), the mean preoperative hospital stay was 11 days, and no patients required a proximal diverting stoma. All of the surgical group resumed normal gastrointestinal function within two weeks, and seven of the nine (78 percent) demonstrated no recurrence of the fistula at a mean follow-up of 8.3 months. Of the 22 medically treated patients, three of the four who received SA healed their fistulas within two weeks. Only two of the other 13 medically treated patients (15 percent) healed their fistulas. Early surgery or the use of SA should be considered in the treatment of patients with low-output intestinal fistulas.

Careful patient selection and preparation for ambulatory inguinal herniorrhaphy combined with monitored local anesthesia result in a safe procedure with excellent patient acceptance. Factors contributing to early and late complications are presented, and the common methods of their treatment are reviewed.

Peripheral blood lymphocytes from controls and from a small population of plutonium workers with internal plutonium depositions, cumulative chronic external irradiation, and occupational exposure to single or multiple chemicals, were analysed for the frequency of sister chromatid exchanges (SCE) and chromosome aberrations. SCE are sensitive to some chemical mutagens, while chromosome aberrations are induced by moderate to high doses of ionizing radiation, and therefore these different cytogenetic end-points are complementary. We analysed the frequency data from workers grouped by internal systemic burdens of plutonium (less than 148, 148-740 and greater than 740 Bq) and to those exposed to five chemicals in the workplace: perchloroethylene, beryllium, carbon tetrachloride, benzene, and trichloroethylene. A significant increase in chromosome aberrations compared with the control frequency was observed only in cells of workers with greater than 740 Bq of internalized plutonium. Based on prior studies, the lack of a dose-response indicator from internal plutonium was not unexpected because of the small sample and the low frequency of aberrations induced at the lower plutonium burdens. There were no significant increases in the SCE mean frequencies when analysed by estimated internal plutonium or from exposure to any of the chemicals.

Five patients undergoing transplantation of autologous bone marrow underwent percutaneous placement of a double lumen central venous catheter into the inferior vena cava by way of the femoral vein. All had conditions that precluded access to the superior vena cava or other sites in the upper part of the torso. Patients ranged in age from 18 to 59 years. The double lumen central venous catheter was inserted using aseptic technique in the operating room, and the catheter exit site was dressed using sterile technique every 48 hours afterward. Patients received all irradiated blood product transfusions, intravenous fluids, intravenous antibiotics, parenteral alimentation and autologous bone marrow reinfusion through the catheter. The duration of severe neutropenia (less than 500 neutrophils per microliter) and severe thrombocytopenia (less than 20,000 platelets per microliter) ranged from zero to 24 days (median of 22 days) and five to 20 days (median of 15 days), respectively. Catheters remained in the groin area 23 to 45 days (median of 35 days). Complications included one catheter-related Streptococcus species infection and one Escherichi coli bacteremia. These infections resolved with the catheter in place after appropriate institution of antibiotics. No episodes of thrombosis, kinking, migration, extravasation of drugs or local infection were noted. Central venous catheters can be safely inserted and maintained in the groin area even in severely immunocompromised patients receiving bone marrow transplants.

Methods that avoid long-term immunosuppression must be developed for human parathyroid allotransplantation to be feasible. Pretransplant treatment of the graft to eliminate passenger cells is one such method. An alternative approach is short-term treatment of the recipients with cyclosporine (CsA). In this study, parathyroid glands from Lewis X Brown Norway rats were cultured for 1 week and treated with antiserum directed against class II major histocompatibility complex antigens. Treated glands were transplanted into hypocalcemic Wistar-Furth recipients that previously received 30 mg/kg of CsA once a day for 3 days before transplantation. At 280 days after transplantation, 67% of the recipients had functional parathyroid allografts. Control rats (no CsA; fresh, untreated glands) rejected these grafts within 28 days. Control rats given 3 days of CsA and transplanted with fresh, untreated glands had functional grafts for greater than 56 days (median survival, 80.5 days). Prolongation of allograft survival with short-term, preoperative CsA demonstrates the efficacy of immunosuppression given at the time of antigen presentation. This course of CsA is even more effective when the recipient receives a graft whose passenger cells are eliminated.

A new case of the Baller-Gerold syndrome is described in a 6 1/2-year-old, black male who presented at birth with bilateral synostoses of the coronal and lambdoidal sutures, bilateral radial aplasia, vertebral anomalies and genito-urinary malformations. The parents and siblings were unaffected, and there was no history of consanguinity. A review of the history and physical findings in our patient and in the four other patients previously reported in the literature is provided, with a discussion on pathogenesis, prognosis and the possible autosomal recessive mode of inheritance of the syndrome.

Plasma glucose, C-peptide, and insulin responses to intravenous glucose (intravenous glucose tolerance test [IVGTT], 0.5 g/kg), glucagon (1 mg i.v.), and oral glucose (oral glucose tolerance test [OGTT], 1 g/kg) were assessed in six normal beagles before, during, and 1 and 4 mo after the administration of cyclosporin A (CsA) in doses previously shown to be required for uniform prevention of canine islet-allograft rejection (20 mg/kg; mean trough radioimmunoassay serum levels greater than or equal to 500 ng/ml). Insulin secretion in response to intravenous glucose and glucagon was significantly inhibited during the administration of CsA (areas under insulin-response curves, pmol.min-1.L-1; IVGTT, pre-CsA, 11,127 +/- 1285; during CsA, 5954 +/- 1147, P less than .05; glucagon tolerance test, pre-CsA, 18,617 +/- 2807; during CsA, 4401 +/- 486, P less than .05 vs. pretreatment levels). These secretory defects persisted 4 mo after CsA was discontinued (IVGTT, 4358 +/- 659; glucagon tolerance test, 10,567 +/- 2479, P less than .05). C-peptide responses paralleled these changes. Plasma glucose disposal in response to these secretagogues, however, returned to normal 1 mo after discontinuation of CsA. In contrast to the findings for IVGTT and glucagon, insulin-response curves to OGTT were not statistically different during CsA administration. We conclude that, although glucose disappearance rates are normal after discontinuation of the CsA administration, CsA causes irreversible impairment in islet secretory responses detectable with IVGTT and glucagon but not with OGTT. These results suggest that short-term CsA in doses required to prevent islet-allograft rejection in dogs can result in permanent loss of functionally competent beta-cells.

Citrullinemia is one of the five aminoacidurias associated with the Krebs-Henseleit urea cycle. A long-term lymphocyte line (UM-21) derived from a patient with this disease and nine of ten clones of this line were found to have no activity for the enzyme argininosuccinate synthetase (AS), as demonstrated by their inability to grow in medium in which citrulline had been substituted for arginine, by their inability to incorporate arginine-C14 derived from citrulline-C14 into cellular protein, and by direct enzyme assay. One clone had normal or nearly normal argininosuccinate synthetase activity, as demonstrated by the same criteria. Nutritional "variants" able to grow logarithmically in medium containing citrulline were isolated from UM-21 and three clones. The apparent Kms of AS for citrulline in UM-21, the ten clones, the variant lines, and a normal line were measured and fell into three groups: AS in UM-21 and nine clones had no measurable apparent Km for citrulline; AS in the variant cells had apparent Kms for citrulline of approximately 20 mM; and AS in the normal cell line and one clone had apparent Kms for citrulline of 0.2 mM. The data suggest that the defect in the citrullinemic cell lines is due to a mutation in the structural gene coding for argininosuccinate synthetase.

Twenty patients with gallstone ileus were treated over a 20-year period. The demographics were typical: mean age 76, female to male ratio of 5:1, and 60 per cent incidence of concomitant medical ailments. An 85 per cent preoperative diagnostic rate was unusually high. An analysis of the study halves demonstrated a stable preoperative diagnostic rate, decrease in preoperative delay (7.5 vs. 4.7 days), and a rise in mortality rate (0 vs. 11%) without an unfavorable effect from a 26 per cent incidence of single-stage procedures (0% mortality). Gallstone ileus still carries a mortality rate of five to ten times that of all other nonmalignant mechanical small bowel obstructions. Anticipated improvements related to augmented preoperative diagnostic yields shortened preoperative delays, and selective surgical management have not been substantiated. Improved mortality rates may await refinements in resuscitation, monitoring, and surgical skills.

A major problem of cytogenetics testing in mammalian cells is lack of agreement of results among laboratories. Our objective was to develop a sensitive in vitro test protocol that was applicable to large-scale chemical screening and yielded comparable results in two laboratories. We used sister chromatid exchange (SCE) and chromosome aberration (CAb) tests in Chinese hamster ovary (CHO) cells. The initial protocol used standard cell densities, medium, batch of rat liver S9 for metabolic activation; positive, negative, and solvent controls; staining and scoring techniques; and fixation times. Treatment without S9 was for 8-12 hr (CAb) or 26 hr (SCE), and with S9 for 2 hr in serum-free medium. Bromodeoxyuridine (BrdUrd) (10 microM) was added to SCE cultures only, 2 hr after addition of the test chemical. Doses were based on the 50% toxicity level in a preliminary test of cell survival 24 hr after treatment. One hundred cells (CAb) or 50 cells (SCE) were scored from each control and from five dose levels. Five clastogens were tested in the first two-laboratory comparison: mitomycin-C, triethylenemelamine, N-methyl-N'-nitro-N-nitrosoguanidine, cyclophosphamide, and benzo(alpha)pyrene. There was quite good agreement between laboratories. Seventeen compounds were then tested "blind" in the two laboratories. As testing proceeded, some discrepancies occurred between the laboratories, and the protocol was modified in attempts to improve the resolution of marginal responses and make dose selection more consistent. The preliminary test for cell survival was omitted. A 10(5) dose range in a half-log series was tested, and cells were scored at the highest dose at which sufficient mitotic cells were obtained, and at the next two lower doses. By delaying fixation times, SCE and CAb were scored at doses that inhibited cell cycle progression. This protocol gave comparable results in the two laboratories in many cases and by testing up to a maximum dose, limited by solubility and/or toxicity, should detect a high proportion of clastogens and SCE inducers.

Recent studies in animals have shown prolonged survival of endocrine allografts after treatment of the graft with Ia antibody prior to transplant. In this study, we documented the presence of Ia bearing passenger cells in human parathyroid and islets of Langerhans. Furthermore, we characterized these cells with regard to their expression of HLA-DQ and HLA-DR molecules using indirect immunofluorescence. We found that passenger cells in parathyroid express both HLA-DQ and HLA-DR. In contrast, islets express only HLA-DR. Parathyroid tissue treated first with polyclonal anti-DR or anti-DQ and complement eliminated cells that reacted with monoclonal anti-DR or -DQ probes, respectively. Similarly, islets treated with polyclonal anti-DR and complement eliminated cells that reacted with monoclonal anti-DR reagents. We believe that further characterization of Ia+ cells in human endocrine tissue will provide information that could be used to enhance allograft survival.

Results from the testing of 108 coded chemicals in Chinese hamster ovary (CHO) cells for the induction of chromosome aberrations and sister chromatid exchanges (SCEs) are presented. All chemicals were tested with and without exogenous metabolic activation, using protocols designed to allow testing up to toxic doses. Cell harvest times could also be extended if chemical-induced cell cycle delay was seen. Chromosome aberrations were induced by 43 of the chemicals, and 66 induced SCEs; 37 of the chemicals were positive for both endpoints.

Methods that avoid chronic immunosuppression of transplant recipients must be developed to eliminate the various risk factors associated with such treatment (e.g., increased infections and malignancies). Pretransplant treatment of the graft with anti-Ia serum plus complement to eliminate "passenger cells" is one such method. An alternative approach is short-term treatment of the recipients with cyclosporine (CsA). In this study, parathyroid glands from Lewis X Brown Norway rats were cultured for one week at 37 degrees C and treated with anti-Ia and complement. Treated glands were transplanted into parathyroidectomized, hypocalcemic Wistar-Furth recipients that had received 30 mg/kg of CsA once a day for the three days prior to transplant. At 1 year posttransplant, 67% of the recipients had functional parathyroid allografts. Control rats (no CsA; fresh, untreated glands) rejected their grafts within 28 days. Controls given three days of CsA and transplanted with fresh, untreated glands all had functional grafts for greater than 56 days (median survival: 80.5 days). Prolongation of allograft survival with short-term, preoperative CsA demonstrates the efficacy of immunosuppression given only at the time of antigen presentation. This course of CsA allowed for indefinite graft survival when the recipient received a graft previously cultured and treated with Ia antiserum. These results are encouraging and should be evaluated further to determine whether similar approaches will be useful in human transplants.

It is a widely held view that objective statistical criteria are needed for the evaluation of genetic toxicity assays. This paper presents statistical methods for the analysis of data from in vitro sister chromatid exchange (SCE) and chromosome aberration tests that use Chinese hamster ovary cells. For SCEs, an extensive study of solvent control results demonstrated that there is a substantial interday component of variability in the data, and that a Poisson sampling model is applicable to data generated via the protocol of Galloway et al [1985]. Consequently, a trend test for evidence of a dose response is proposed for such SCE data. As an illustration of this statistical method, analysis of data previously considered to be negative [Gulati et al, 1985] indicates that di(2-ethyl-hexyl) phthalate induces a weak, but reproducible, SCE dose response in CHO cells. Monte Carlo methods are used to show that the trend test is more sensitive than four other statistical procedures considered for the analysis of Poisson-distributed SCEs. A similar trend test for dose response in proportions is proposed for chromosome aberration data, where the percent of cells with chromosome aberrations is the response of interest. Sensitivity (or power) studies indicate that three doses and a control with 50 cells/dose point is a reasonable design for an in vitro SCE study that uses the Galloway et al protocol. For in vitro chromosome aberrations, however, three doses and a control with 100 cells/dose point appears to produce too insensitive an assay; an increase to 200 cells/dose point in the Galloway et al protocol seems worthy of serious consideration.

We here report the establishment of a seemingly permanent hybrid cell line formed by fusion of the cells of two biochemically mutant human lymphocyte lines. One parental line (UM-1-6TGr) was deficient in hypoxanthine-guanine phosphoribosyl transferase (IMP: pyrophosphate phosphoribosyltransferase, EC 2.4.2.8), and had two marker chromosomes. The second parental line (UM-21-5) was a clonal derivative of a citrullinemic lymphocyte line, and was, like the line of origin, dificient in argininosuccinic acid synthetase [(L)-Citrulline: (L)-aspartate ligase (AMP-forming), EC 6.3.4.5]. This line also had a marker chromosome, which was a B5 with a very prominent secondary constriction. After trypsinization of both parental lines, followed by addition to the fusion mixture of beta-propiolactone-inactivated Sendai virus, the cells were placed in a doubly selective medium (hypoxanthine-aminopterin-thymidine-containing medium in which the arginine was replaced with citrulline) to prevent the proliferation of the mutant parents. Under selective conditions, 97-99% of cells were found to be tetraploid, containing the three marker chromosomes; and the specific activities of the hybrid line transferase and synthetase were intermediate between normal and mutant line values. Furthermore, the UM-1-6TGr and UM-21-5 lines were producers of gamma and mu heavy chains of immunoglobulin, and of kappa light chains, as determined by immunodiffusion and immunofluorescence, and the hybrid line continued to synthesize and to secrete detectable levels of these same immunoglobulins. These studies demonstrate the genic and cytogenetic stability of this hybridized lymphocyte cell line, and prove that hybridization per se does not extinguish the activity of either the regulatory of structural genes involved in immunoglobulin synthesis.

We have studied the pattern of chromosome instability in cultured fibroblasts and fetal membrane cells from a fetus aborted by an individual with a history of a previous child affected with Fanconi anemia (FA). These cells exhibited a low level of spontaneous chromosome instability. Upon treatment with diepoxybutane (DEB), chromosome breakage increased to a level comparable to that reported earlier in DEB-treated FA heterozygous cells. Cultured cells derived from chromosomally normal fetuses which served as controls did not show DEB-induced chromosome breakage. This observation suggests that the fetus studied is heterozygous for the FA gene. The ability to distinguish readily between the three genotypes (homozygous FA, heterozygous FA, and normal) in an in vitro stress system that measures the response of the cells to a clastogenic agent makes available a test for the prenatal and postnatal detection of the FA gene.

The activity of argininosuccinate synthetase (E.C. 6.3.4.5), a urea cycle enzyme, was measured in cultured human lymphocytes using a new radioactive assay. Control cells had a maximum specific activity of 15.7 +/- 8.7 nmoles per hour per milligram of protein and an apparent Km for citrulline of 2 X 10(-4) M, whereas cells derived from a patient with citrullinemia had no detectable activity. A nutritional variant, selected out of the citrullinemic lymphocyte population by ability to grow in citrulline, had a maximum specific activity of 10.7 +/- 3.8 nmoles/hr/mg and an apparent Km for citrulline of 2 X 10(-2) M. These measurements confirm the observation that citrullinemia is associated with a defect in argininosuccinate synthetase activity and provide further evidence that citrullinemia is expressed in cultured lymphocytes. The emergence of a nutritional variant with a partial defect in argininosuccinate synthetase enzyme suggests that this citrullinemic patient has a heterogeneous population of cells, some totally defective and others only partially defective in argininosuccinate synthetase. The new activity assay is described in detail.

Two lymphocytoid cell lines have been established from a patient with the Lesch-Nyhan syndrome. The cells are deficient in hypoxanthine-guanine phosphoribosyltransferase, as demonstrated by their failure to incorporate [H(3)]hypoxanthine and by their inability to grow in medium in which they were nutritionally dependent upon exogenous hypoxanthine. This represents the first establishment of presumptively permanent human lymphocytoid cell lines that are deficient in a specific enzyme.

The chromosomes of leucocytes cultured from the peripheral blood of 49 primitive Yanomama Indians of Venezuela were studied to determine the types and frequencies of aberrations in a human population not exposed to the same exogenous agents as civilized man. In all but one instance, 100 cells per individual were scored. In 13 cases, we found one or more cells with multiple complex breaks and rearrangements, represented by tetracentric, tricentric, and numerous dicentric chromosomes. From the standpoint of chromosomal damage, these cells are among the most abnormal cells yet described in vivo in man, and were not seen in the controls. There was also a higher than expected frequency of cells with an isolated structural aberration in both Indians and controls. This may be the result of a 24- to 48-hour delay in the initiation of culture. The cause of the more extensive damage to some cells remains to be determined.

Immunoglobulin production was studied in established lines of normal human lymphocytes. Three lines which produced both immunoglobulin G and immunoglobulin M were cloned. Among the 25 immunoglobulin-producing clones, 23 produced both classes of immunoglobulins. These findings suggest that the phenomenon of genic exclusion does not hold for immunoglobulin production in lymphocytoid cells in culture.