Search PubMed⌕ Search

Biomedical subjects

J Rubin

Publications and source records attributed to J Rubin.

At least 397 records · Page 22Linked to original sources
PubMedDate not supplied

Localized bumps of activity sustained by inhibition in a two-layer thalamic network.

Based on head direction experiments in rats, the existence of localized bumps of thalamic activity has been proposed. We computationally demonstrate the existence of a novel class of localized bump solutions in a two-layer conductance-based thalamic network and analyze the mechanisms behind these stable patterns. In contrast to previous models of bump activity, here inhibition plays a crucial role in initially spreading neuronal firing and in subsequently sustaining it. In our model, we incorporate local strong, fast GABA(A) inhibition and diffuse weak, slow GABA(B) inhibition, based on previous biophysical experiments. These forms of inhibition contribute in different, yet complementary, ways to the observed pattern formation.

Animals↗
PubMedDate not supplied

Intraperitoneal feeding.

This study evaluated the peritoneal cavity as the sole route for alimentation in 300 g growing rats. Initial studies demonstrated that a solution of high osmolality was required to provide sufficient calories. A nutrient solution was formulated by mixing 20% glucose with electrolytes (10 ml) and 8.5% amino acids with electrolytes (20 ml). Instilling 30 ml of nutrient solution induced an IP volume of 60 ml, which was absorbed in 24 hours. Rats were studied in four groups for 7 days. One group received nutrient solution IP (n = 10); a second group received the same amount PO (n = 10); the third group received electrolytes IP (n = 10); and a fourth group was fed rat chow PO (n = 10). Rats fed this nutrient solution (IP and PO) were acclimatized by administering one third of their required nutrient the first 4 days. On the next 3 days they received two thirds of their required nutrient. Both groups fed nutrient solution (IP and PO) lost 23% body weight. Electrolyte and rat chow fed groups lost 26% and gained 8% of body weight, respectively. Due to the high osmolality (1200 mOsm/L) of this nutrient solution, sufficient food could not be delivered via the peritoneal cavity to adequately feed growing rats. Studies were then initiated to formulate another nutrient solution that contained lipids. This solution (678 mOms/L) contained 20% glucose with electrolytes (10 mls), 8.5% amino acids with electrolytes (20 ml), and 10% lipids without electrolytes (30 ml). Glucose and amino acids contained the same electrolyte concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

Prevalence of HIV virus among patients undergoing continuous ambulatory peritoneal dialysis.

It is unclear whether patients should be tested for the presence of HIV antibody. This test has taken upon itself a significance beyond a simple hemoglobin. Extreme views on testing are prevalent, both from the Centers for Disease Control, which does not recommend routine testing, to physicians advocating screening. The prevalence of HIV virus in our population undergoing continuous ambulatory peritoneal dialysis was investigated. Eighty-two patients ranging in age from 7-72 years were screened. There were seven positive results by both ELISA and Western Blot assays. Four had no risk factors, except for transfusion therapy before HIV screening. Three were known homosexuals. Only two of the HIV positive patients and three of the rest of the dialysis population had serologic markers for Hepatitis B infection. This 9% prevalence was much higher than expected. Although the data suggest that the risk to the health care worker is low, current recommendations to treat all patients as if they may be HIV positive protect the hospital or dialysis facility but may be unworkable. The health care workers attention is not focused because they do not differentiate between low and high risk patient groups. Furthermore, the number of patients who acquired the virus prior to routine screening is unknown. Because most dialysis patients were alive and transfused during this time period they may have inadvertently acquired the virus. If others share these findings, the implications for control of this disease are frightening, as the risk of transmission to patients' sexual partners is not inconsequential. I believe these findings support routine screening for HIV antibody.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Absorption of sulfamethoxazole and albumin from the peritoneal cavity.

The rates of disappearance of sulfamethoxazole and albumin from the peritoneal cavity were measured in humans. Albumin was added to the peritoneal cavity in concentrations commonly found during peritonitis (250-500 mg/100 ml) to ascertain if protein binding within the peritoneal cavity inhibited absorption from the peritoneal cavity. There were no statistical differences between the removal rates; 64-70% of the administered dose was absorbed after 180 min of intraperitoneal residence. The addition of albumin to the peritoneal cavity did not alter absorption of sulfamethoxazole. The total protein removed in dialysate effluent in the absence of albumin was 1,653 +/- 906 mg. The protein losses when albumin was added to dialysate [( albumin + control losses] - losses in dialysate drainage) were 1,037 +/- 2,305 mg and 1,364 +/- 1,653 mg for the 6 and 12 g studies.

Adult↗
PubMedDate not supplied

The effect of ABO and Rh blood type on the response to intravenous immune globulin (IVIG) in children with immune thrombocytopenic purpura (ITP).

PURPOSE: Immune thrombocytopenic purpura (ITP) is a common childhood illness characterized by thrombocytopenia secondary to shortened platelet survival. Medical therapy includes corticosteroids, intravenous immune globulin (IVIG), and IV Rho (D) immunoglobulin (anti-D). Individuals with Rh-negative blood generally do not respond to treatment with anti-D, but little information is currently available regarding the potential relationship between blood type and response to IVIG. This study was designed to characterize the relationship between ABO and Rh blood type and the response to IVIG in children and adolescents with newly diagnosed ITP. PATIENTS AND METHODS: A retrospective chart review was performed for 52 children and adolescents with newly diagnosed ITP initially treated with IVIG by the Division of Pediatric Hematology-Oncology at Robert Wood Johnson University Hospital in New Brunswick, New Jersey. RESULTS: There were no significant differences in response rate or clinical outcome by ABO blood group or Rh type in children with ITP who received IVIG monotherapy as their initial treatment. CONCLUSIONS: ABO blood group and Rh type do not appear to be prognostic factors when IVIG monotherapy is the initial treatment for childhood ITP.

ABO Blood-Group System↗
PubMedDate not supplied

The presence of somatostatin receptors in malignant neuroendocrine tumor tissue predicts responsiveness to octreotide.

In 77 percent of patients suffering from a malignant carcinoid syndrome, administration of the somatostatin analog, octreotide (SMS 201-995, Sandostatin) induced clinical improvement coupled with a decrease in 24-hour urinary 5-hydroxyindole acetic acid (5-HIAA). This finding prompted an evaluation to determine the correlation between the presence of somatostatin receptors in tumor tissue and the response to octreotide in patients with advanced, metastatic, neuroendocrine tumors. In tissues of 31 tumors (20 carcinoid, eight islet-cell carcinoma, three medullary thyroid carcinomas), the presence of somatostatin receptors was analyzed by binding of the somatostatin analog 125I-Tyr3-SMS 201-995 and autoradiography. Receptors were detected in 16 of 20 samples of carcinoid tissues; all but one patient with receptor-positive tumors improved clinically after treatment with octreotide, and the urine 5-HIAA level was reduced a median of 63 percent (range, 39-94 percent) compared to values before treatment. Of the receptor-negative carcinoid patients, only one showed clinical improvement, which was minimal, and there was a negligible reduction in 5-HIAA after octreotide therapy. All eight patients with metastatic islet-cell carcinomas were positive for somatostatin receptors. Symptomatic improvement and a > 50 percent decrease in the level of at least one of the pathologically elevated marker hormones was seen in all eight. None of the three patients with medullary carcinoma of the thyroid had a decrease in calcitonin, and all three were initially somatostatin receptor-negative. We conclude that the presence of somatostatin receptors in malignant neuroendocrine tumor tissue appears to correlate with the response to octreotide therapy. Analysis of somatostatin receptors in malignant neuroendocrine carcinoma tissue should be included in future prospective clinical trials of this synthetic peptide.

Amino Acid Sequence↗
PubMedDate not supplied

A prospective randomized evaluation of chronic peritoneal catheters. Insertion site and intraperitoneal segment.

The insertion site (midline or through the lateral rectus muscle) and type of chronic dialysis catheter (straight or spiral intraperitoneal segment) were evaluated in a prospective randomized trial. Dialysis catheter complications and catheter survival were the endpoints of evaluation. Eighty-five first catheters were evaluated. Neither race, gender, renal diagnosis, type of catheter, nor insertion site was a determinant of dialysis catheter survival. Overall median catheter survival was 308 days. There were 40 catheter complications (70%, n = 28) that occurred during the first 61 days following insertion. Median time to the first complication occurring within the first 61 days was 3 days. Late catheter removals were due to peritonitis episodes that failed to resolve. Complications are frequent with peritoneal dialysis catheters, and care of the peritoneal dialysis catheters requires constant vigilance.

Adult↗
PubMedDate not supplied

Complications of Tenckhoff catheters post removal.

Complications due to Tenckhoff catheters can occur at prolonged intervals after their removal. From January 1979 to October 1989, 431 patients at our center began continuous ambulatory peritoneal dialysis (CAPD), 278 of whom subsequently transferred to another form of renal replacement therapy. We identified 12 patients (4.3% or 12/278) with post removal catheter complications. There were 14 post removal complications, two each in two patients, and one in each of 12 others. The mean time to complication was 541 +/- 143 days (27-2,040). In 71% (10/14) of the complications, an abscess was found at the site of the previously removed Tenckhoff catheter. In 29% (4/14) of the complications, foreign body material consistent with a retained cuff was recovered. Documentation at the time of Tenckhoff catheter removal should include a statement regarding the presence of the Tenckhoff catheter cuffs, and patients with retained cuffs should be monitored closely for the development of abscesses or other complications. Immunocompromised patients are at high risk for these complications.

Abscess↗
PubMedDate not supplied

Intraperitoneal insulin--a dose response curve.

To determine a dose response curve for intraperitoneal (i.p.) insulin using Sprague-Dawley rats, human insulin was administered i.p. in 1.5% glucose dialysate at the following doses: 10 U (2.19 U/100 g body wt); 5U (1.23 U/100 g body wt); 2 U (0.49 U/100 g body wt); 1 U (0.27 U/100 g body wt). A bolus injection of glucose was given to elevate blood sugar, followed by infusion of D20%. Blood sugar was maintained at 250 mg/dl by checking at 10 minute intervals and adjusting the IV infusion. Dialysate with regular insulin was instilled after blood sugar was constant for 20 minutes. The end-point was the amount of glucose to maintain a blood sugar of 250 mg/dl after instillation of dialysate and regular insulin. Mean blood sugars were similar within and between each dose group. The effect of regular insulin was noted within 10 minutes. The amount of glucose used with the IV dose differed from all other (p less than 0.05). The amount used by the 5 and 10 U doses of i.p. insulin were similar. Increasing amounts of glucose are required to maintain the blood sugar at increasing doses of intraperitoneal regular insulin up to 5 U. Thus, there appears to be a dose response curve for i.p. insulin.

Animals↗
PubMedDate not supplied

The minimal importance of the hollow viscera to peritoneal transport during peritoneal dialysis in the rat.

The authors investigated whether the abdominal viscera are important surfaces for peritoneal transport by performing peritoneal dialysis in rats without their abdominal viscera and again when the parietal walls were shielded from contact with dialysate. Urea, creatinine, glucose, and inulin were added to the peritoneal cavity and the percentage of the administered dose absorbed was calculated. Controls with and without parietal shields only absorbed 11% more urea and creatinine, 5-15% more glucose, and 7-12% more inulin, respectively, than eviscerated rats. The findings raise the possibility that the abdominal contents do not account for most of peritoneal transport.

Absorption↗
PubMedDate not supplied

Randomized phase II trial of rubidazone and adriamycin in women with advanced breast cancer.

Thirty-eight females with advanced breast cancer who had failed prior chemotherapy were entered in a randomized study of rubidazone (150 mg/m2 iv over 1 hour) versus Adriamycin (60 mg/m2 iv over 5 minutes), both given every 4 weeks. The two treatment groups each contained 19 patients and were similar with respect to age, menopausal status, dominant disease status, Eastern Cooperative Oncology Group performance score, and prior hormonal therapy and chemotherapy exposure. No regressions (complete or partial) were observed with rubidazone, but four (21%) patients achieved regressions (one complete and three partial) with Adriamycin. Considering all cycles, hematologic toxicity included leukopenia (wbc count nadir of less than 4000/mm3) in 88% of patients receiving rubidazone and in 89% of those receiving Adriamycin. Three of eight patients treated with Adriamycin after rubidazone failure achieved a regression. Rubidazone appears to be of little value in the treatment of patients with advanced breast cancer who have failed prior chemotherapy.

Adult↗
PubMedDate not supplied

Early clinical trial of a 1-day intermittent schedule for pentamethylmelamine.

An early clinical trial of pentamethylmelamine (PMM) the monodemethylated derivative of hexamethylmelamine, was conducted in 22 adults with solid tumors. PMM was administered as a 2-hour iv infusion every 4 weeks at doses ranging from 40 to 2400 mg/m2. A combination of gastrointestinal and neurologic (CNS) toxicity was dose-limiting. Nausea and vomiting began at a dose of 265 mg/m2 and became progressively worse until it became life-threatening at doses of 1800-2400 mg/m2. CNS toxic effects consisting of agitation, confusion, drowsiness, and loss of consciousness were first noted at a dose of 1200 mg/m2 and were seen in varying degrees at all higher dose levels. No other toxic effects were noteworthy except two instances of thrombocytopenia at low doses. No antitumor activity was observed. We do not recommend the further use of this schedule of administration for PMM.

Adult↗
PubMedDate not supplied

Lack of clinical therapeutic synergism between cyclophosphamide, adriamycin, and cis-dichlorodiammineplatinum(II) in metastatic human colorectal carcinoma.

Thirty patients with metastatic adenocarcinoma originating in the colon or rectum were treated with a combination of cyclophosphamide, Adriamycin, and cis-dichlorodiammineplatinum(II). Only one partial tumor regression of 12 weeks' duration was observed. Severe nausea and vomiting secondary to chemotherapy were frequently seen. This three-drug regimen, as employed in our study, was not associated with useful clinical activity against human metastatic colorectal cancer.

Adenocarcinoma↗