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D Kahn

Publications and source records attributed to D Kahn.

At least 163 records · Page 9Linked to original sources
PubMed1994

The effect of a tumour necrosis factor antibody on the regenerative response after partial hepatectomy in rats.

In this study we investigated the effect of tumour necrosis factor (TNF) on the regenerative response after partial hepatectomy. Adult male rats were injected intravenously with an antibody to TNF immediately after partial hepatectomy. Animals were sacrificed at 0, 24, 48, 72 and 96 h postoperatively. Hepatic thymidine kinase (TK) activity, liver weight to body weight (LW/BW) ratio, and mitotic index (MI) were used as indices of hepatic regeneration. The rats treated with TNF-Ab had significantly lower levels of TK activity in the liver at 24 h postoperatively compared to the saline treated animals. Furthermore the peak hepatic TK activity was delayed to 48 h in the rats treated with TNF-Ab. The mitotic indices and LW/BW ratios in the TNF-Ab- and saline-treated animals were similar. These data suggest that TNF potentiates the regenerative response after partial hepatectomy.

Animals↗
PubMed1994

Effects of fludrocortisone on sympathetic nerve activity in humans.

Fludrocortisone reduces plasma norepinephrine in healthy humans, but forearm vascular and pressor responses to norepinephrine are potentiated. The effects of fludrocortisone on sympathetic nerve activity in healthy humans are not known. To investigate these effects we evaluated muscle sympathetic nerve activity, heart rate, and arterial pressure in 11 healthy volunteers during three protocols: (1) before and on day 7 of fludrocortisone (0.4 mg/d) treatment with ad libitum diet (n = 6); (2) before and on day 7 of fludrocortisone (0.4 mg/d) or placebo with a 150 mmol/24 h (mEq/24 h) sodium diet (n = 7); and (3) before and on day 2 of fludrocortisone (0.4 mg/d) or placebo with a 150 mmol/24 h (mEq/24 h) sodium diet (n = 4). Placebo did not alter any parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Mycobacterial infection in renal transplant recipients.

STUDY OBJECTIVE: To determine the prevalence and presentation of mycobacterial infection as well as the influence on outcome in graft function and patient survival in renal transplant recipients at our institution. DESIGN: A retrospective review of case records of all renal transplant recipients from 1980 to 1992. SETTING: Groote Schuur Hospital, a large teaching hospital and regional tertiary referral center in Cape Town, South Africa. PATIENTS: During the period reviewed, 857 transplants were performed. The records of 487 patients who had remained in Cape Town were examined. RESULTS: There were 22 cases of mycobacterial infection (21 confirmed or presumed Mycobacterium tuberculosis and 1 unidentified Mycobacterium other than tuberculosis). In seven cases, immunosuppression had been intensified within 3 months of diagnosis. The median time from transplantation to diagnosis was 14 months (range, 2 to 74). Chest radiograph findings included consolidation (14), miliary pattern (4), pleural effusion (3), tuberculoma (2), cavitation (2), and hilar lymphadenopathy (1). Diagnosis of tuberculosis was made on sputum smears (eight), pleural biopsy specimen (two), fine-needle aspiration (one), and fiberoptic bronchoscopy in ten cases (brushings, eight; transbronchial biopsy specimen, three). Extrapulmonary tuberculosis (in addition to pulmonary tuberculosis) occurred in five patients (tuberculous meningitis, one; renal tuberculosis, one; and dissemminated infection, four). Five of the seven patients in whom immunosuppression had been intensified had concurrent infections; two of these died and the remainder returned to dialysis within 6 months. All but one patient received three antituberculosis drugs, including rifampin and isoniazid, for between 6 and 18 months. At the end of the period of review, 12 (59 percent) patients were alive, 10 with functioning grafts and 2 receiving dialysis. Four patients died while receiving antituberculosis treatment, but death was only directly related to tuberculosis in one case. CONCLUSIONS: Tuberculosis is an important infection in renal transplant recipients in Cape Town, but disseminated disease is less common than reported elsewhere.

Adult↗
PubMed1994

Diagnosis of recurrent brain tumor: value of 201Tl SPECT vs 18F-fluorodeoxyglucose PET.

OBJECTIVE: This prospective study was designed to compare the sensitivity and specificity of a relatively simple examination, 201Tl chloride single-photon emission CT (SPECT), with a more complex examination, 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), in patients thought to have recurrent brain tumor. Because both agents have been shown to be markers of viable tumor, we hypothesized that their sensitivity and specificity should be the same. SUBJECTS AND METHODS: Nineteen patients with evidence of recurrent tumor on CT or MR images were studied with both 201Tl SPECT and FDG PET imaging. Two patients were examined twice, so a total of 21 studies were evaluated. The 201Tl SPECT and FDG PET examinations were performed on the same day in 17 patients, and the remaining four examinations were done within 1 week of one another. Three reviewers independently interpreted each Tl SPECT and PET scan. Inappropriate regional increases in 201Tl or FDG activity were considered indicative of tumor recurrence. Sensitivity and specificity values were based on biopsy results and clinical follow-up. The final diagnosis was tumor recurrence in 16 cases and radiation necrosis in 5 cases. The relationship of scan results to survival was analyzed. RESULTS: The sensitivity and specificity of the 201Tl examination for detecting tumor recurrence were 11 (69%) of 16 and two (40%) of five, respectively; values for the FDG PET examination were 13 (81%) of 16 and 2 (40%) of 5, respectively. In patients with recurrent tumors less than 1.6 cm in size, results were false-negative in four 201Tl SPECT examinations and three FDG PET studies. All tumor lesions 1.6 cm or larger (n = 8) were detected. Agreement among the three nuclear medicine specialists was complete for each of the 201Tl SPECT scans. There was disagreement on the interpretation of five (24%) of the 21 FDG PET scans, which was resolved by consensus. Scintigraphic findings did not correlate with patients' survival times. CONCLUSION: We were unable to detect a statistically significant difference in sensitivity or specificity between the 201Tl SPECT and FDG PET scans. Both techniques were sensitive for tumor recurrence with lesions less than 1.6 cm or larger. However, given the greater availability, simplicity, and ease of interpretation and the lower cost of the 201Tl SPECT studies, this technique should be considered for detection of tumor recurrence with lesions that are demonstrated to be 1.6 cm or larger on CT or MR examinations.

Adult↗
PubMed1994

Radiolabeled antibody imaging of patients with potentially resectable colorectal adenocarcinoma.

Thirty-two patients with potentially resectable recurrent colorectal adenocarcinoma were imaged with the radioimmunoconjugate 111In-satumomab pendetide to determine whether imaging supplies clinically relevant information relating to the extent of disease in patients with different presenting characteristics. Patients included 12 with increasing carcinoembryonic antigen (CEA) without anatomical evidence of recurrence, 13 with radiological abnormalities consistent with apparently isolated metastases, and 7 with recurrence and anatomical abnormalities of unclear significance. 111In-satumomab pendetide imaging detected extrahepatic abdominal and pelvic disease in 16 subjects. Imaging was most informative in patients with recurrent disease and anatomical abnormalities of unclear significance, but imaging of the liver was suboptimal owing to high levels of nonspecific uptake. We conclude 111In-satumomab pendetide imaging can supply clinically relevant information relating to the extent and location of recurrent colorectal adenocarcinoma in patients with extrahepatic abdominal and pelvic radiological abnormalities of unclear significance and in radiologically normal patients with high CEA levels.

Adult↗
PubMed1994

The first 100 kidney transplants from living related donors at Groote Schuur Hospital.

Improved results with cadaver kidney transplantation and the increase in the number of cadaver organs have caused the continued use of donor kidneys from living relatives to be questioned. In this analysis of our first 100 renal transplants involving a living related donor, the 5-year graft survival rate was 70%. The 5-year graft survival rate for recipients of grafts from HLA-identical donors was 81%, as opposed to the 64% survival rate for grafts from one-haplotype donors. Recipients of grafts from one-haplotype-matched donors who received donor-specific blood transfusions demonstrated better graft survival than those who were not transfused. This analysis demonstrates that the results of living related kidney transplantation are good, and suggests that donor-specific blood transfusions may be beneficial.

Graft Survival↗
PubMed1994

Ultrasonographic growth and Doppler hemodynamic evaluation of fetuses of obese women.

All fetuses benefit from ultrasonographic estimation of gestational age and evaluation of growth patterns. Monitoring the pregnancies of obese women is perceived as more difficult than monitoring those of nonobese women. The aim of this study was to determine if maternal obesity affects the growth and Doppler resistance indices (RI) of the fetus. Twenty-eight women with a preconception weight > 90.7 kg underwent obstetric ultrasonographic evaluations from the 20th week of gestation. Their ultrasonographic data were compared with those of controls. Ten of the obese women developed gestational diabetes and had lower umbilical artery RIs for a given gestational age (P < .0001) than did those obese women without other medical complications, those with medically controlled pregnancy-induced hypertension or those from the control population. The relation between fetal unit weight and umbilical artery RIs was established. The pattern of RI changes was similar in all groups when estimated fetal weight instead of gestational age was used as the covariant. Fetal growth and Doppler velocimetry can be monitored adequately in obese women. Gestational diabetes significantly influences the pattern of fetal growth and the impedance to flow in the umbilical artery.

Adult↗
PubMed1994

Placement of a double lumen silastic catheter for hemodialysis access through the cephalic vein.

The cephalic vein within the deltopectoral groove provides adequate access to the central venous system for the PermCath hemodialysis catheter. Unlike EJV techniques, which are successful in few instances, the cephalic vein approach was successful in approximately 75 percent of instances. In addition, the rate of complications secondary to bleeding or catheter kinking are decreased with the cephalic vein technique as compared with insertion through the EJV or IJV. We conclude that the cephalic vein is a dependable and functional approach to the central venous system for the PermCath hemodialysis catheter.

Adult↗
PubMed1993

Disordered hemostasis in extrahepatic portal hypertension.

To assess the contribution of naturally occurring portal-systemic shunts to the coagulopathy of patients with liver disease, we studied laboratory parameters of hemostasis in 20 adult patients with extrahepatic portal hypertension, secondary to portal vein thrombosis, that had resulted in variceal bleeding. All extrahepatic portal hypertension patients had normal liver function and histological appearance. None had any evidence of preexisting coagulation disorders, and none had bled or undergone sclerotherapy in the 6 mo before study. Age- and gender-matched groups of 20 healthy individuals and 20 stable patients with cirrhosis and portal hypertension who had a history of variceal bleeding served as controls. Both patient groups had thrombocytopenia consistent with hypersplenism and portal hypertension. Prothrombin international normalized ratio (extrahepatic portal hypertension, 1.3 +/- 0.12; cirrhosis, 1.7 +/- 0.2; control, 1.02 +/- 0.06; p < 0.05) and partial thromboplastin time ratios (extrahepatic portal hypertension, 1.12 +/- 0.1; cirrhosis, 1.26 +/- 0.2; controls, 1.01 +/- 0.03; p < 0.05) were significantly prolonged in both patient groups. Extrahepatic portal hypertension and cirrhotic patient groups had significantly increased levels of serum total fibrin(ogen)-related antigen (extrahepatic portal hypertension, 818 +/- 150 ng/ml; cirrhosis, 454 +/- 52 ng/ml; controls, 124 +/- 7.3 ng/ml; p < 0.05), fibrin monomer (extrahepatic portal hypertension, 168.8 +/- 16.9 ng/ml; cirrhosis, 115.6 +/- 11.1 ng/ml; controls, 19.7 +/- 0.4 ng/ml; p < 0.05) and D-dimer (extrahepatic portal hypertension, 118 +/- 9.6 ng/ml; cirrhosis, 129 +/- 10 ng/ml; controls, 53.2 +/- 1.6 ng/ml; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Renal transplantation in patients with bilateral renal carcinoma--how long should we wait?

Patients with bilateral renal carcinoma or malignancy in a solitary kidney are best managed by radical nephrectomy with subsequent dialysis and transplantation. Because of the risk of recurrence of the tumour, the timing of the transplant procedure is important. We report on two patients with bilateral renal carcinoma who were subjected to radical nephrectomy and then managed with dialysis and transplantation within 6 months.

Adenocarcinoma↗
PubMed1993

Control involving metabolism and gene expression: the square-matrix method for modular decomposition.

Control of DNA supercoiling by the free-energy of hydrolysis of ATP that involves gene expression is analyzed in terms of three levels of unconnected metabolic pathways. These are synthesis and breakdown of topoisomerase mRNAs, synthesis and breakdown of topoisomerase proteins and supercoiling and relaxation of DNA. The so-called square-matrix method previously developed for the control of metabolic pathways, is extended to deal with this hierarchical control system. It turns out that also in this case, the matrix of control coefficients is equal to the inverse of the so-called elasticity matrix, which contains all relevant elasticity coefficients as well as information about the structure and connectedness of the pathways involved. For a simpler case of a hierarchy of two systems, we demonstrate that the explicit matrix inversion method may be replaced by an implicit in which the regulatory effects that run through the other level are described by an additional elasticity coefficient which may then be treated as if local.

Adenosine Triphosphate↗
PubMed1993

Gender of donor influences outcome after orthotopic liver transplantation in adults.

Because male and female livers not only differ with respect to estrogen and androgen receptor content, but also demonstrate sexual dimorphism of certain functions, we examined the effect of donor gender on graft survival following liver transplantation (OLTx) in adults. Between February 1981 and February 1988, 982 OLTx procedures were performed in 789 adult patients at the University of Pittsburgh. In this study, OLTx was categorized as a failure if the patient died or required retransplantation within 60 days of the surgery. When the donor-recipient gender combinations were male-male, male-female, and female-female, the failure rates were 28%, 28%, and 36%, respectively. In contrast, 60% of female donor livers failed in male recipients. Compared to the pooled donor-recipient gender combinations, the odds of failure for female-male liver grafts were increased 3.7-fold (95% confidence interval: 6.5, 2.1; P < 0.001). These findings may result, at least in part, from alterations in the sex hormone milieu or changes in the graft estrogen or androgen receptor content.

Adult↗
PubMed1993

Modular analysis of the control of complex metabolic pathways.

The understanding of the functioning of the intact cell would be simplified appreciably if it were possible first to analyze particular modules of cell physiology separately, and then to integrate the information so as to yield understanding of the control structure in terms of the mutual regulation of the modules. Here we develop a quantitative method based on Metabolic Control Analysis that makes this possible: The relevant properties of the modules are contained in "overall" elasticity coefficients, which reflect the changes in fluxes in the module upon a small variation of the environment of the module, allowing the latter to attain steady state. We show how overall control coefficients, which reflect the control exerted by the processes catalyzed by each module, can be expressed into the overall elasticity coefficients. We derive corresponding summation and connectivity theorems. A number of possible divisions of physiological systems into modules is discussed. This work is a generalization of previous analyses of overall control properties in that it allows for multiple fluxes to connect the modules, and reaction stoichiometries of any complexity.

Cell Physiological Phenomena↗
PubMed1993

An emission-based technique for obtaining attenuation correction data for myocardial SPECT studies.

In this paper, a technique is described for obtaining the information needed to perform attenuation correction in the thorax entirely from an emission study. This technique is based on the observation that the variation in soft tissue and lung attenuation coefficients is small among individuals. Thus only the outer contours of the body and lungs need be determined for obtaining the attenuation map. The contours are determined by using 99Tcm-macroaggregated albumin (MAA) to locate the lungs and an external source wrapped about the chest to locate the body boundary. Simulation studies were performed to investigate how errors in the presumed tissue attenuation coefficients affect the accuracy of the correction. Body and lung attenuation coefficients were varied from 20% less to 20% more than the coefficients used in the corrections. Over this range, there was less than a 15% alteration in the relative distribution of counts in the left ventricle. To test clinical feasibility, seven patients referred for clinical myocardial perfusion studies were scanned before and after the placement of the body source and the administration of 99Tcm-MAA. Reconstructed images from these studies showed clear demarcation of all body and lung boundaries. The presence of 99Tcm-MAA in the lungs had no significant effect on the clinical interpretation of the single photon emission computed tomographic (SPECT) studies. It is concluded that this technique is feasible for clinical application and that it offers important advantages over other current methods.

Adult↗