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Biomedical subjects

R Jacobs

Publications and source records attributed to R Jacobs.

At least 217 records · Page 12Linked to original sources
PubMed1987

A phase I-II study of bialkylator chemotherapy, high-dose thiotepa, and cyclophosphamide with autologous bone marrow reinfusion in patients with advanced cancer.

Twenty patients with disseminated cancer both untreated and previously treated received bialkylator chemotherapy, thiotepa, and cyclophosphamide and reinfusion of cryopreserved autologous bone marrow (ABMR). The cyclophosphamide dose was constant at 7.5 g/m2 over three days, while thiotepa was started at 1.8 mg/kg for three days in escalating dose by a modified Fibonacci schema to 7 mg/kg. The median time to recovery of more than 500 granulocytes and more than 50,000 platelets/microL was 18 and 27 days, respectively. Four patients died as a consequence of severe, overwhelming infections or progressive disease during their period of aplasia. Of the 18 evaluable patients, a complete response (CR) was achieved in three patients and a partial response (PR) in ten patients for an overall response rate of 72%. The median duration of response was 14 weeks. Other nonhematologic toxicities included nausea/vomiting, diarrhea, stomatitis, skin rash, and cardiomyopathy. The maximum tolerated dose (MTD) of thiotepa was 700 mg/m2 or 6 mg/kg for three doses. Although there are substantial toxicities associated with this regimen, high-dose thiotepa and cyclophosphamide produce high response rates in patients with disseminated cancer.

Adult↗
PubMed1986

Spherocytosis associated with anaplasmosis in two cows.

Spherocytes were detected on blood smears of 2 Angus cows. The RBC from both cows had increased fragility in hypotonic saline solution, supporting the presence of spherocytes. Other laboratory tests revealed a macrocytic, regenerative anemia with anisocytosis, polychromasia, basophilic stippling, Howell-Jolly bodies, nucleated RBC, and Anaplasma marginale organisms. A complement-fixation test was positive for anaplasmosis in cow 1 and a direct Coombs' test was positive for immunoglobulin G in both cows.

Anaplasmosis↗
PubMed1986

Effect of hypoxia on the initiation of secondary wool follicles in the fetus.

The development of secondary wool follicles in single fetal sheep subjected to hypobaric hypoxaemia was studied. One group of pregnant ewes were exposed to 57.1 kPa from 30 to 135 days gestation. Fetal weights (mean +/- s.d.) for the hypoxaemic group (3.35 +/- 0.53 kg; n = 4) were significantly lower than for the controls (4.19 +/- 0.31 kg; n = 3, P less than 0.05). At 110 days gestation, a second group had arterial and venous catheters surgically implanted into the ewe and fetus and skin samples were taken from the fetus. At 120 days gestation (10 days after surgery) these animals were subjected to hypoxia for 20 days, at a level to maintain fetal carotid pO2 between 1.47 and 1.87 kPa (mean carotid pO2 for the control fetuses was 2.84 +/- 0.28 kPa). Fetal weight at 140 days was not significantly different in the hypoxaemic and control groups. Morphometric analysis revealed that the secondary to primary follicle ratio (S:P) was less in both groups of hypoxaemic fetuses than in their respective controls. Although hypoxia for 20 days did not significantly alter fetal weight, it produced a low S:P ratio similar to the longer-term hypoxaemic animals. It is concluded that hypoxia has a marked effect in reducing the initiation of secondary follicles in the last third of gestation.

Animals↗
PubMed1985

Prevention of gastrointestinal bleeding in burns: the effects of cimetidine or antacids combined with early enteral feeding.

The efficacy of prophylactic therapy with cimetidine or antacids combined with early enteral feeding to prevent gastrointestinal bleeding in patients with severe burns was evaluated. Fifty patients with burns exceeding 30 per cent of the total body surface area (TBSA) were divided into two groups, each of them treated by one of these agents in combination with early feeding. Bleeding was not encountered in either group. It is assumed that the combination of either agent with enteral feeding early in the post-burn course equally protected against gastrointestinal bleeding. Because of the ease and lack of side-effects of cimetidine in this series, its use was preferable.

Adult↗
PubMed1985

Cloning and characterization of Plasmodium falciparum FCR-3/FMG strain.

The FCR-3/FMG African strain of Plasmodium falciparum was cloned by the limiting dilution technique in in vitro culture to obtain parasite populations derived from a single cell. The basic in vitro culture technique used was that of Trager and Jensen, performed in microtiter culture plates. The cloning sequence was repeated serially three times, and three parasite clones with a higher than 99% probability of single cell derivation were isolated. Two of these clones were determined by electron microscopic examination to possess the K+ and one the K- trait. The clones were found to be equally sensitive to chloroquine in vitro but varied in their in vivo pathogenicity for Aotus, the K- clone being non-pathogenic.

Animals↗
PubMed1985

The blood supply of experimental liver metastases. VIII. Increased capillary blood flow within liver tumors with administration of epinephrine.

Capillary blood flow has been studied with a laser doppler probe in normal liver tissue and within Walker carcinosarcoma tumors implanted in the livers of rats. Epinephrine, in doses from 1 to 100 micrograms injected as a bolus into the portal system caused immediate significant rises in tumor capillary blood flow. These effects lasted approximately 1 minute and were followed by secondary decreases in flow. Aortic blood pressures rose with epinephrine administration and remained elevated for periods longer than the increase in tumor capillary flow. The effects of epinephrine on liver capillary flow were dose related; doses of 5-10 micrograms caused a decreased flow, 3 micrograms produced a biphasic response, and 1 microgram resulted in an increase in flow. It is concluded that epinephrine produces a short but significant increase in capillary blood flow within the central parts of these tumors, in areas previously considered "avascular".

Animals↗
PubMed1984

Enzymes of cerebral GABA metabolism and synaptosomal GABA uptake in acute liver failure in the rabbit: evidence for decreased cerebral GABA-transaminase activity.

Measurements of the activities of the two key enzymes in cerebral GABA metabolism--glutamate decarboxylase (GAD) and GABA-transaminase (GABA-T)--were performed in normal rabbits and in rabbits with hepatic encephalopathy due to galactosamine-induced liver failure. Furthermore the uptake of GABA by synaptosomes was studied. Hepatic encephalopathy was associated with a marked decrease in the activity of GABA-T. This decrease in activity was already apparent in galactosamine-treated rabbits before the onset of hepatic encephalopathy. Sera and serum ultrafiltrates of rabbits with hepatic encephalopathy but not of normal rabbits or of rabbits with uremic encephalopathy were shown to inhibit GABA-T activity in vitro. Cerebral GAD activity and synaptosomal GABA uptake in rabbits with hepatic encephalopathy and in untreated animals were not different. These later findings indicate that hepatic encephalopathy is not associated with alterations of presynaptic GABA nerve terminals in the central nervous system. The demonstration of a decrease in cortical GABA-T activity provides indirect evidence for decreased GABA turnover in the brains of rabbits with hepatic encephalopathy and thus is compatible with augmented GABA-ergic inhibitory neurotransmission contributing to the neural inhibition of hepatic encephalopathy.

4-Aminobutyrate Transaminase↗
PubMed1984

Porcelain gallbladder: ultrasound and CT appearance.

Nine patients with calcification of the gallbladder wall (porcelain gallbladder) were analyzed by ultrasound and the appearance correlated with the CT, radiographic, clinical, and surgical findings. Three distinct patterns were identified: (a) a hyperechoic semilunar structure with acoustic shadowing posteriorly, simulating a stone-filled gallbladder devoid of bile, which was seen in 5 patients; (b) a biconvex , curvilinear echogenic structure with variable acoustic shadowing, seen in all 3 patients with carcinoma of the gallbladder; and (c) an irregular clump of echoes with posterior acoustic shadowing, seen in 1 patient. Potential pitfalls in the diagnosis of gallbladder calcification are presented, and the association between calcification and cancer is emphasized.

Aged↗
PubMed1984

Rings of cross-striated fibrils within the cat cone pedicle: a computer-assisted serial EM analysis.

Using serial electron micrographs and a computer reconstruction system the authors have examined the three-dimensional cytoarchitecture of the cat cone pedicle. These reconstructions reveal that within each pedicle is a closed 4-6 micron diameter ring of cross-striated fibrils similar to the nonring structures described in photoreceptor inner and outer segments by others in guinea pig, rat, chick, monkey, and humans. Our cone pedicle rings encompass the invaginating synaptic contacts of the cone bipolars and horizontal cells and have periodic 70 nm striations surrounding bundles of fibrils about 100 nm in diameter. The authors suggest that these striated rings may be active contractile elements and could be responsible for shape changes in cone pedicles during dark adaptation.

Animals↗
PubMed1984

Visual evoked potentials in a rabbit model of hepatic encephalopathy. I. Sequential changes and comparisons with drug-induced comas.

The recording of visual evoked potentials in rabbits has been shown to be an objective, reproducible, noninvasive technique for quantitating changes in the pattern of cerebral neuronal activity. The development of hepatic encephalopathy due to galactosamine-induced fulminant hepatic failure was consistently associated with a series of distinctive changes in the visual evoked potential waveform. The pattern of the visual evoked potential in hepatic coma (due to galactosamine-induced fulminant hepatic failure) differed fundamentally from that in ether-induced coma, but was identical to that in comas induced by three drugs which activate gamma-aminobutyric acid-ergic neural mechanisms: pentobarbital, diazepam, and muscimol. These findings are compatible with activation of the gamma-aminobutyric acid inhibitory neurotransmitter system contributing to cerebral neuronal inhibition in hepatic coma due to galactosamine-induced fulminant hepatic failure.

Animals↗
PubMed1983

Scanning electron microscope observations on the structure of portal veins, sinusoids and central veins in rat liver.

Portal veins can be recognized in SEM by the presence of an accompanying element such as the bile ductule. Endothelial cells within these vessels possess small marginal microvilli. Portal veins show few sinusoidal inlets (direct connections to sinusoids) and no attached "wandering" cells. Sinusoids in periportal areas are narrower and more tortuous than the wider and straighter central ones. Periportal endothelial fenestrae have a larger diameter (111 nm) than central ones (105 nm), but their number per square micron, and therefore the porosity (% open area), is higher in centrolobular sinusoids (7.94 vs 5.96%). Central veins have smoother endothelial cells and show numerous sinusoidal outlets (direct sinusoidal connections). Cells are seen attached to the wall and are probably migrating out of the liver. In the orifices of some sinusoidal outlets, traversing bars can be observed, which obstruct the flow of blood from the sinusoids into the central vein. From our observations and measurements the following conclusions can be drawn: a. In the narrower periportal sinusoids, moving blood cells will be forced against the wall, causing a massage of the space of Disse. This will influence the exchange of fluids and particles through the endothelial fenestrae, and it will cause stirring of the fluid in the space of Disse. b. Centrolobular sinusoids have a larger perimeter and an endothelial lining with a higher degree of porosity. These structural factors will favour transport and uptake processes in the centrolobular parenchyma. c. Sinusoidal blood flow might be expected to be slower in central areas, since the number of sinusoids appear to equal that of the portal region, but their lumen is wider.

Animals↗
PubMed1983

Psychological aspects of chronic pain.

Since its inception in June 1979, over 500 patients have been treated at the King/Drew Pain Center in Los Angeles. Based upon the treatment and observations of this patient group, this paper describes the psychologic aspects in patients suffering from chronic abdominal pain, low back pain, phantom limb pain, chest pain, and arthritic pain.

Adult↗