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Biomedical subjects

S Vogel

Publications and source records attributed to S Vogel.

At least 109 records · Page 6Linked to original sources
PubMed1989

[Neuroradiologic diagnosis of elongated spinal tumors].

Elongated spinal space-occupying lesions are infrequent but not rare. They are found at all ages, most frequently in the thoracic spinal canal and are primarily of gliomatous origin. A survey of our cases from the last 25 years shows the enormous progress in the diagnosis of such processes. This applies to technical quality as well as improved diagnostic information of modern methods and significantly less discomfort to the patient. In the case of suspected space-occupying lesions, a consecutive diagnostic program is recommended, that implies first conventional radiographs of the structure of the spine (including tomography if necessary) followed by myelography with modern positive contrast media. Myelography should be combined with CT. Plain CT-scans can demonstrate hypodense or calcified tumours. MRT provides essential additional information by three dimensional imaging and the corresponding signal processing techniques. With increasing MRT-capacities and improving image quality medullary tumours will primarily investigated with this method. The relations between multiple intramedullary cavities can be explored by endomyelography before drainage.

Adolescent↗
PubMed1988

Cytochrome oxidase histochemistry in the rat hippocampus. A quantitative methodological study.

The diaminobenzidine (DAB) method was adapted for the microphotometric determination of cytochrome c oxidase (cyt ox) in the rat hippocampus. The qualitative and quantitative investigations at the light microscopic level showed that acetone and cytochrome c pretreatment of cryostat sections resulted in a significant increase of demonstrable cyt ox activities. The final incubation medium consisted of 7.5 mM DAB, 2% polyvinylalcohol (PVA) and 6% dimethyl sulfoxide in 0.1 M Hepes buffer; final pH 7.5. PVA was used to keep DAB and artificially oxidized DAB in solution. In the kinetic and endpoint measurements a linear response of the reaction with highest slope was observed only in the initial 5-6 min of reaction. Thereafter the slope decreased. Ultracytochemical demonstrations, which were performed as a topochemical control, showed reaction product only in mitochondria (cristae and intermembranous space). In contrast to vibratome sections all mitochondria reacted positively in cryostat sections of aldehyde-fixed hippocampi. The enhancement of reaction after acetone pretreatment of cryostat sections (light microscopic level) and after a freezing step in ultracytochemistry is discussed in connection with diffusion problems of DAB through mitochondrial membranes.

3,3'-Diaminobenzidine↗
PubMed1988

Quantitative succinate dehydrogenase histochemistry in the hippocampus of aged rats.

Quantitative histochemical methods (microphotometric kinetic and end-point measurements, and morphometric analyses of reactive areas) were used to investigate the levels of succinate dehydrogenase (SDH) in the hippocampus of young adult (3-6 months old) and aged male rats (24-27 months old). Methodological studies concerning the demonstration of SDH activity, which were performed using hippocampi of young animals, revealed a linear relationship between the reaction time and the amount of reaction product for up to 20 min; kinetic (continuous) and end-point measurements provided the same results. In a number of experiments, it was established that an incubation medium consisting of 100 mM succinate, 10 mM sodium azide, 3 mM nitro blue tetrazolium chloride, 0.25 mM phenazine methosulfate, and 7.5% polyvinylalcohol in 0.05 M Hepes buffer (final pH 7.5) was optimal for quantitative SDH histochemistry in the hippocampus. Comparative quantitative investigations of SDH activity in rat hippocampi showed that, in most regions and layers of the hippocampus of both young and aged rats, the levels of SDH activity increased along the rostrocaudal axis of the hippocampus, i.e., higher levels were present in the caudal than in the rostral pole. In both groups, the highest SDH levels were observed in the molecular layer of the cornu ammonis (CA)-1, the CA-3, and the fascia dentata (middle and outer thirds), most of which are termination fields of the excitatory perforant path arising from the regio ento-rhinalis. Furthermore, in almost all of the investigated layers, the older animals exhibited lower SDH levels than young animals. These differences were statistically significant in the molecular layer of the fascia dentata and in most layers of the CA-3. The lower SDH levels in aged animals are discussed in relation to the reduced capacity for energy metabolism in the aging brain.

Aging↗
PubMed1988

Phase I-II pilot of whole abdominal radiation and concomitant 5-FU as an adjuvant in colon cancer: a Southwest Oncology Group Study.

Thirty-eight patients with Stage B2, C1 or C2 colon cancer (Astler-Coller Modification of Dukes) received 3000 rads whole abdominal radiation and concomitant intermittent bolus 5-FU as part of a phase I-II adjuvant trial. Patients whose tumor penetrated the serosa (B2 or C2) in addition received a 1600 rad boost to the tumor bed. 5-FU was administered only during radiation. It was given at a dose of 300 mg/m2 days 1-5 and 28-32 in 21 patients (Group A) and day 1-3 and 28-31 in 17 patients (Group B). Median follow-up time for Group A is 44 months. Group A patients have a disease-free survival of 66% and overall survival of 73% at 44 months. The 16 C2 patients in Group A have a disease-free survival of 54% and overall survival of 65% at 44 months. There was a 26% incidence of moderate to severe acute toxicity in Group A but no long term bowel, liver, or hematologic toxicity. One patient developed acute myelogenous leukemia 2 years after treatment. Group B patients had only a 6% incidence of moderate to severe toxicity, but had a disease-free survival of 60% and overall survival of 100% at median follow-up of 23 months. Group B Stage C2 patients had a disease-free survival of 53% and overall survival of 100% at this same follow-up period. Disease-free and overall survival in Group A Stage C2 patients is superior to that in several published trials. Given the manageable toxicity, adjuvant whole abdominal radiation with concomitant 5-FU and tumor bed boost should be tested in a randomized fashion for possible therapeutic benefits.

Abdomen↗
PubMed1988

Effect of nimodipine on the regional cerebral acidosis accompanying thiamine deficiency in the rat.

The effect of the calcium channel blocker nimodipine on the previously described regional cerebral acidosis accompanying thiamine deficiency was investigated. Local cerebral pH (LCpH) and blood flow (LCBF) were separately determined autoradiographically in normal and 16-day thiamine-deficient rats administered the calcium antagonist drug and compared to appropriate controls. Nimodipine did not modify LCpH in normal brain. In thiamine deficiency, nimodipine significantly raised LCpH in 5 of 17 structures evaluated, two of which, the medial dorsal nucleus of the thalamus and the mammillary body, are vulnerable to the development of histological lesions in this condition. Although the calcium blocker augmented LCBF in normal brain, it had no effect on the hyperperfusion already present by day 16 of thiamine deprivation. Thus, the pH changes we are reporting are probably not related to an effect on cerebral perfusion, but could have resulted from an improved ability of the brain to reduce its proton load in the presence of nimodipine. These results may have wider therapeutic implications than in thiamine deficiency alone.

Animals↗
PubMed1987

Hepatorenal syndrome. Studies of the effect of vascular volume and intraperitoneal pressure on renal and hepatic function.

Eleven patients with well-documented hepatorenal syndrome were studied by measurement of blood volume, glomerular filtration rate, renal plasma flow, plasma aldosterone concentration, renin substrate concentration, and plasma renin activity. They were then given 750 ml of stored plasma, 750 ml of fresh frozen plasma, and then an infusion of angiotensin II, in random order on successive days. Infusion of fresh frozen plasma improved function more than did stored plasma and in addition returned a very low filtration fraction toward normal. Angiotensin II infusion increased filtration fraction, but decreased glomerular filtration rate, renal plasma flow, and urine flow sharply. Patients were then given a daily infusion of 1,000 ml of fresh frozen plasma for seven to 18 days to expand the blood volume to supranormal levels as assayed by serial measurement of blood volume. Plasma aldosterone levels decreased to a normal range, glomerular filtration rate and renal plasma flow both increased, and urinary excretion of sodium and potassium both returned toward normal. The effect of intraperitoneal pressure was then studied by measuring glomerular filtration rate, renal plasma flow, pressure in the vena cava, hepatic vein free flow, and hepatic vein wedged pressure before, during, and after paracentesis to reduce the intraperitoneal pressure from 30 to 40 cm H2O to 12 to 17 cm H2O. Venous pressures moved parallel to ascitic fluid pressures, and glomerular filtration rate, renal plasma flow, and urine flow all improved sharply; then, as ascitic fluid continued to form, reducing vascular volume, urine flow, glomerular filtration rate, and renal plasma flow all decreased slowly. Six patients then underwent placement of a LeVeen shunt. Improvement in glomerular filtration rate and renal plasma flow and clinical condition was dramatic. During postoperative observation of up to two years, progressive improvement in hepatic function has occurred.

Angiotensin II↗
PubMed1987

A phase II trial of vinblastine in patients with advanced or recurrent endometrial carcinoma. A Southwest Oncology Group Study.

Forty-one patients with advanced or recurrent endometrial carcinoma no longer amenable to control with surgery and/or radiotherapy were entered into study. Five of these were ineligible for study. One eligible patient never received any treatment, another had no baseline information recorded; these were thus inevaluable. The remaining 34 patients received continuous infusion vinblastine (1.5 mg/m2) as a 24-h infusion daily for 5 days every 3 weeks. One complete and 3 partial responses were observed among these 34 patients, for an overall objective response rate of 12%. Two of these 4 responders are deceased, and 2 remain alive with disease at 18 and 22 months, respectively. The most common toxicity noted was leukopenia in 22 patients (65%); 12 (35%) of these had severe or life-threatening leukopenia (less than 2,000 WBC/microliter). Fourteen of the 34 (41%) experienced nausea and vomiting. Other adverse effects were less common. Overall, 15 of the 34 patients (44%) experienced severe or life-threatening toxicity. In this trial, continuous infusion vinblastine was toxic and had minimal to moderate efficacy at best. These facts suggest that the drug at the dose and schedule tested has no role in the management of advanced or recurrent endometrial carcinoma.

Adenocarcinoma↗
PubMed1986

Chromosomal localization of integrated adenovirus DNA in productively infected and in transformed mammalian cells.

The in situ hybridization technique has been used to localize adenovirus type 12 (Ad12) genomes on specific chromosomes of Ad12-transformed hamster cells as well as on specific chromosomes of human cells productively infected with Ad12. Hamster cell lines T637 and A2497-2 contain 20 to 22 and 17 copies of Ad12 DNA, respectively, in an integrated form. The results of in situ hybridization experiments demonstrate that the Ad12 DNA molecules are predominantly located on chromosomes 2, 7, 11 to 13, and 15 in cell line T637, and on chromosomes 7, 20, and perhaps 16 to 19 in cell line A2497-2. These data further document that viral DNA is chromosomally integrated and does not persist in a huge extrachromosomal, episomal structure. There is evidence from previous work that adenovirus DNA can also be covalently linked to human cellular DNA after productive adenovirus infection of human cells. In keeping with these earlier findings, we have now been able to show by in situ hybridization experiments that early in productive infection, i.e., 2 or 6 hr after infection, Ad12 genomes are predominantly associated with a limited number of human chromosomes. It appears biologically significant that these chromosomes, which belong to groups A and CII, have been the same ones in several independent infection experiments. Other chromosomes may also carry smaller amounts of viral DNA. In situ hybridization of Ad12 DNA to chromosomes of uninfected human cells yields no significant chromosomal association of viral DNA. The signal to noise ratio of grain counts over chromosomes from Ad12-infected cells to areas devoid of chromosomes is 5.6. The results presented raise the question of whether Ad12 DNA can integrate at selective sites in human chromosomes and whether this insertion event plays an essential role in early steps of viral transcription or replication. There is no direct evidence to suggest a biologic function for viral DNA integration in the productive infection cycle.

Adenoviruses, Human↗
PubMed1986

Assignment of conserved amino acid residues to the ATP site in the protein kinase domain of the receptor for epidermal growth factor.

The ATP substrate site in the epidermal growth factor (EGF) receptor was mapped by using a series of 26 ATP derivatives with modifications at the base, ribose or triphosphate moiety. Ki values for these derivatives were determined by competition with [gamma-32P]ATP. The enzyme seems to interact specifically with the beta-phosphate in an ion-pair bond with the N-6 amino group at the adenine in a hydrogen bond. With ribosyl-2-aminopurine triphosphate and GTP, the enzyme most likely recognizes the 2-amino group in a hydrogen bond. This high specificity for ATP and GTP is unique for the ATP site in the EGF receptor among all investigated protein kinases. The available data on the interaction between ATP derivatives and protein kinases were used to assign conserved amino acid residues found in diverse protein kinases to the ATP site in this type of enzyme.

Adenosine Triphosphate↗
PubMed1986

Polyamines stimulate the phosphorylation of phosphatidylinositol in membranes from A431 cells.

The phosphorylation of phosphatidylinositol in plasma membranes from A431 cells was investigated using [gamma-32P]ATP as the substrate. Phosphatidylinositol 4-phosphate was found to be the major product after an incubation time of 5-10 min. Little, if any, phosphatidylinositol 4,5-bisphosphate was found under these conditions. Epidermal growth factor (EGF) had no effect on the formation of phosphatidylinositol 4-phosphate or phosphatidylinositol 4,5-bisphosphate. On the other hand, the polyamines spermidine and spermine stimulated the phosphatidylinositol kinase activity about eightfold yielding almost exclusively phosphatidylinositol 4-phosphate as the reaction product. Half-maximum stimulation by spermidine occurred under near physiological conditions (1.5 mM). Furthermore various proteins and amino acid polymers containing clustered basic amino acid residues (e.g. histones and polylysine) stimulated the formation of phosphatidylinositol 4-phosphate to a similar extent. Half-maximal concentrations for the activation were considerably lower ranging from 1.5 microM to 80 microM. The ATP specificity of the phosphatidylinositol kinase(s) was investigated with a small set of selected ATP derivatives. In the presence of spermidine the specificity changed significantly indicating that (a) spermidine acts on a kinase and not on a phosphatase, (b) this activity is distinct from the EGF-receptor protein kinase activity. The results do not suggest an involvement of the EGF receptor in the growth-factor-dependent formation of phosphatidylinositol phosphates. It is proposed that the phosphorylation of phosphatidylinositol by polyamines might be a mechanism to replenish the pool of inositolphospholipids.

1-Phosphatidylinositol 4-Kinase↗
PubMed1986

Carbon monoxide levels in cardiac patients in an urban emergency department.

Arterial carboxyhemoglobin (COHb) levels of patients who presented to an emergency department with cardiopulmonary complaints were determined. The purpose of the study was to see whether COHb levels of these patients indicated an acute risk factor in the severity of exacerbation of their cardiac disease. Factors known or thought to increase COHb levels (smoking and arrival by ambulance, for example) were correlated with COHb levels and final diagnoses of myocardial infarction, exacerbation of stable angina or congestive heart failure, asthma, and chronic obstructive pulmonary disease. Statistically significant increases in COHb were found in patients admitted to the intensive care unit and with proven myocardial infarction over a control group. However, these differences could be accounted for by smoking alone or by instrumental margin of error and were not thought to be related to ambient urban carbon monoxide.

Asthma↗
PubMed1986

Combined alkylators and multiple-site irradiation for extensive small cell lung cancer: a Southwest Oncology Group Study.

The Southwest Oncology Group performed a study for patients with extensive small cell lung cancer in which two hypotheses were tested: that combined alkylating agents for induction might improve the initial response rate; and that multiple-site, involved-field consolidation with irradiation in patients with response to chemotherapy might further improve response quality and duration. A regimen of combined alkylating agents plus vincristine [carmustine, thiotepa, vincristine, and cyclophosphamide (BTOC)] was compared to our standard program of cyclophosphamide, doxorubicin, and vincristine (CAV). Patients with bone marrow metastases and/or disseminated bone metastases were randomized to BTOC or CAV as initial induction therapy, but received no multiple-field irradiation afterward. Among 189 such patients, the overall response rates were similar (48% to BTOC and 61% to CAV, with complete remission in 5% and 15%, respectively). Toxic effects were also comparative, with 23% sustaining life-threatening or fatal complications on BTOC and 16% on CAV. Median survival (5.9 and 7 months for BTOC and CAV, respectively) and overall survival were not different, and are superimposable upon our previously reported results with CAV alone. For patients with no evidence of bone marrow involvement and no metastases identified beyond the confines of ipsilateral hemithorax, liver, and brain, the plan of therapy consisted of induction chemotherapy (BTOC or CAV) every 3 weeks for three cycles, followed by multiple-field irradiation consolidation to sites of prior involvement. Among 239 such patients, response rates to therapy initiated with BTOC and CAV were also similar: 54% for BTOC and 62% for CAV, with complete response in 16% and 13%, respectively. However, the program of BTOC followed by multiple-site irradiation was associated with a higher incidence of severe or life-threatening thrombocytopenia (23% versus 8% for CAV), accounted for almost entirely by patients receiving hepatic irradiation after chemotherapy, among whom the incidence of this complication (grade 3 or 4) was 76% and 14%, respectively. Other toxic effects, including granulocytopenia, were comparable. With the exception of thrombocytopenia in the cited subgroup, multiple-field irradiation consolidation proved feasible and tolerable, with improved quality of response evident after its initiation in 24% of 135 patients. However, a similar proportion developed disease progression during or shortly after radiation therapy, and the median survival of patients who received irradiation was only 9 months (7 months from the start of consolidation).(ABSTRACT TRUNCATED AT 400 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

Genetically-engineered microorganisms: I. Identification, classification, and strain history.

We have argued that accurate identification of the microorganism will form a cornerstone of the assessment of potential hazard. Appropriate methodology for identification exists, and is continually under development and refinement. Organizations such as the American Type Culture Collection will perform certified identifications for relatively low cost. Thus there appears to be little reason that an organism should not be identified insofar as current microbiology allows prior to submission for PMN review. We suggest that a complete microbiological characterization be considered an essential element of an acceptable PMN. To accomplish this, however, current institutional arrangements for the protection of trade secret information needed in the process of identification may need to be improved. An accurate identification of the strain will often provide access to important information with which to evaluate its ecology, pathogenicity, biochemistry, and genetics. Specialized texts, the scientific literature, and professional consultation are ready sources of such information. However, a major effort should be made to establish a data base that can specifically address the needs of biohazard evaluation. This could be done, in part, by collecting information about the construction, and about the behavior in the environment of genetically-engineered microorganisms that are now under development and will soon be tested or used. Identification information may also eventually be useful for the formulation of hypotheses about possible modes of harm or about relative safety, based on phylogenetic relationships. This is a very difficult undertaking at present, however. Microbial taxonomy is currently in a process of radical reevaluation as new macromolecular sequence information reveals previously unsuspected phylogenetic relationships, and disturbs categorizations based on older types of traits such as morphology, etc. This means that both inferences about relative safety and about possible modes of harm from taxonomic relationships must be highly tentative based on current information. Regulatory authorities may wish to consider requesting confirmatory DNA hybridization data or other macromolecular sequence comparisons in cases where strong arguments related to safety must be made from taxonomic information in relatively poorly studied groups of organisms. Detailed strain histories would provide valuable information for safety evaluations.(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteria↗
PubMed1985

Transient global amnesia: diagnosis in the emergency department.

Transient global amnesia is a not uncommon presentation of acutely altered neuropsychiatric status. It is, however, a clinical diagnosis that requires a careful history with attention to inciting events, risk factors for cerebrovascular disease, the absence of other abnormalities on neurological examination, and normal results of laboratory studies. Knowledge of the generally benign course of TGA can facilitate the care and psychological support of these patients and their families.

Adult↗