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Biomedical subjects

S Wagner

Publications and source records attributed to S Wagner.

At least 397 records · Page 22Linked to original sources
PubMed1989

Lingual vibrotactile threshold shift during magnitude-estimation scaling: effects on magnitude-estimation responses and scaling behavior.

The purpose of the present study was to determine if lingual vibrotactile threshold shifts occurred during magnitude-estimation scaling of suprathreshold stimuli presented to the dorsal surface of the tongue. Possible relationships of the lingual vibrotactile threshold shifts to suprathreshold stimulus intensity, magnitude-estimation responses, and overall scaling behavior were explored. A single group of 24 subjects with an age range of 18 to 22 years participated in this study. Each subject performed two magnitude-estimation tasks. In one of the tasks, threshold of sensitivity was determined after every suprathreshold numerical response of the subject. If a threshold shift was recorded, threshold was allowed to return to the pretest baseline level before continuing to the next suprathreshold stimulus presentation. The results showed that threshold shift did occur during lingual vibrotactile magnitude-estimation scaling, and that it was related to suprathreshold stimulus intensity. The results also showed that the numerical magnitude-estimation responses of the subjects were different for the two scaling tasks. Overall scaling behavior of the subjects in the form of power-function exponents was not different for the two tasks.

Adolescent↗
PubMed1989

The provisional normal MSAFP screen.

Patients with a provisional normal MSAFP screen appear to be at significant risk of giving birth to a child with a chromosomal abnormality. Failure to recognize this risk or act upon it may deprive patients of all of their reproductive options. Based upon our experience over an 18 month period, a protocol to evaluate the provisional normal MSAFP is reported.

Adult↗
PubMed1989

Cine magnetic resonance imaging: tomographic analysis of left ventricular function.

Cine magnetic resonance imaging has the attributes that enable its use as a method for quantitating the three-dimensional functional geometry of the ventricles. The completely noninvasive nature of this technique is advantageous for sequential studies needed to monitor evolution of cardiac disease and response to therapy. This article reviews the authors' experiences with this technique for the evaluation of left ventricular and valvular function.

Aortic Valve Insufficiency↗
PubMed1988

Ribosomal DNA inheritance and recombination in Neurospora crassa.

The genetic segregation of ribosomal DNA (rDNA) in Neurospora crassa was analyzed by exploiting restriction fragment length polymorphisms in the nontranscribed spacer (NTS) sequences of nine laboratory wild-type strains and wild-collected strains. In an analysis of random spore progeny from seven crosses, and of ordered tetrads from two of those crosses the rDNA was shown to be inherited in a simple, stable Mendelian fashion, exhibiting an approximately 1:1 ratio of the two parental rDNA types. No meiotic recombinants were detected among the progeny, indicating that non-sister-chromatid crossing over is highly suppressed in the rDNA region. The basis for this suppression of meiotic recombination is not known.

Crosses, Genetic↗
PubMed1988

Intercalated cells as a probable source for the development of renal oncocytoma.

Renal oncocytoma is a distinct type of epithelial tumor said to arise from the collecting duct system. Here we show that in nine of ten oncocytomas the tumor cells expressed an analog of the erythrocyte anion exchanger band 3. In the normal kidney band 3 is confined to the basolateral surface of the majority of intercalated cells which comprise up to 50% of the cortical collecting duct epithelium. Carbonic anhydrase c is another protein abundant in intercalated cells, and this was also expressed in six of the ten oncocytomas investigated. Immunoreactivity specific for band 3 and carbonic anhydrase c was not detected in any of the 20 renal cell carcinomas examined. At favourable section planes direct transitions between normal collecting ducts and oncocytic tubules were observed. These findings suggest that oncocytomas may develop from intercalated cells of the collecting duct epithelium.

Adenoma↗
PubMed1988

Adjustment to intermittent access in rats drinking saccharin: I. Pauses in drinking.

Hungry rats drink saccharin solutions avidly. When access to the cylinder is restricted, so that it is available during alternate 30-sec periods rather than continuously, rats adjust to this constraint so that total amount of lapping, over each period of a few minutes each, is defended. We show that the rats achieve this defense, in part, by pausing less often and for briefer periods between bursts. Log-survivorship analysis of the pauses in drinking suggests (a) that they are generated by two processes with different time constants, (b) that early in the session, both processes are suppressed when access is restricted; and (c) that later in the session, pauses reflecting the shorter-term process begin to appear, even if access is restricted. Therefore, adjustment to constraints on access is achieved in part by suppression or inhibition of two processes that generate pauses, and the suppression is relaxed earlier for the one with shorter time constant.

Animals↗
PubMed1988

Sham drinking of glucose solutions in rats: some effects of hydration.

Sham-drinking patterns were observed in rats with oesophageal fistulae and gastric cannulae. In rats both food- and water-deprived at test, first-session sham intake was an inverted U-shaped function of glucose concentration (the preference-aversion pattern). Sham intake at low and high extremes rose with repeated exposure, so that the function flattened. When the rats were hydrated by a gastric water preload, sham intake of glucose at low concentrations was much reduced, whereas sham intake at high concentrations was little affected, so that the function became monotonic increasing. This time sham intake rose with repeated testing at high concentrations, but not low ones, so that the function steepenned. At low concentrations, the low sham intakes reflected a rapid termination of the sham-drinking bout. This does not reflect a delayed effect of the gastric water load, for introducing a further delay between load and drinking test did not enhance the effect. Finally, an intragastric load of isotonic NaCl was less effective than water in suppressing sham drinking, just as it is less effective in inhibiting thirst. We conclude: (1) sham drinking is terminated by an accumulation of orosensory feedback; and (2) the taste presented to the mouth, and the animal's hydrational status, jointly determine the amount of such feedback that is necessary to end the ingestive bout.

Animals↗
PubMed1988

Glucose sham drinking in the rat: satiety for the sweet taste without the sweet taste.

In rats sham drinking through oesophageal fistulae, sham intake of a dilute glucose solution (0.25 M) is greatly reduced, but not abolished, by an intragastric water preload. Since no further fluid enters the body, the early cessation of sham drinking must reflect a purely oral control, set by hydrational status. We show that lapping after the water load is abolished if the rat has sham-drunk appreciable quantities before the load is delivered. This is true even if the initial sham drinking is of plain water, with no sweet taste. Therefore, (1) the effect of the preload is to set the total quantity of oral feedback required to end the sham drinking bout; and (2) the necessary oral feedback is provided by the lapping response itself. It does not depend upon gustation.

Animals↗
PubMed1988

Monoclonal antibodies selectively directed against the cell wall surface of Mycobacterium tuberculosis.

In the last few years several monoclonal antibodies against Mycobacterium tuberculosis have been described, but their use as diagnostic tools has been limited. In this study we describe eight monoclonal antibodies against M. tuberculosis for diagnostic purposes. The monoclonal antibodies were selected after enzyme-linked immunosorbent assay screening with whole bacterial suspensions of mycobacteria and other bacterial species. Four monoclonal antibodies (BS100, BS101, BS102, and BS104) reacted with a whole bacterial suspension of M. tuberculosis but not with the other mycobacteria. When tested with a cytoplasmic fraction of mycobacteria the same monoclonal antibodies showed a broad cross-reactivity. Therefore the monoclonal antibodies showed not specific but selective binding to M. tuberculosis. The molecular size of the recognized antigens ranged from 12 to 71 kilodaltons as determined by the immunoblotting technique. The ability to differentiate M. tuberculosis from mycobacteria other than tuberculosis was investigated by enzyme-linked immunosorbent assay with 131 freshly cultured strains of M. tuberculosis from patients and 36 strains of mycobacteria other than tuberculosis. The monoclonal antibody BS104 could clearly distinguish between M. tuberculosis and other mycobacterial species.

Antibodies, Bacterial↗
PubMed1988

Evaluation of a dual-antigen ELISA test for the serodiagnosis of tuberculosis.

Two antigen preparations from Mycobacterium tuberculosis and M. bovis, respectively, were used in an enzyme-linked immunosorbent assay (ELISA) to quantitate the level of IgG antibodies in samples of 169 sera obtained in India from 75 patients with pulmonary tuberculosis and from 94 controls. The results of the two ELISA tests were integrated using defined criteria. All the controls were correctly classified by this dual-ELISA approach and only two patients were categorized as false negatives. The method has a specificity of 1.00 and a sensitivity of 0.974, while the gain in the certainty of diagnosis was 1.974, only slightly less than the ideal value of 2.00.

Adolescent↗
PubMed1988

Pancytopenia in a patient receiving home intravenous nutrition.

A patient is described who developed pancytopenia several months after home intravenous nutrition (IVN) was started following a major small bowel resection for volvulus. In the post-operative period his weight fell by about 15 kg to 45 kg. Bone marrow aspiration and leucokinetic studies were carried out which suggested that bone marrow failure was the cause of this patient's haematological abnormalities. Five of the 16 patients at St Mark's Hospital who are receiving home IVN were noted to have had transient neutropenia. In 3 of these patients significant weight loss was also noted in the few months preceding the development of neutropenia. It is suggested that there is an association between relative energy malnutrition and the development of the haematological abnormalities that have been observed. In the patient described here these abnormalities were prolonged.

Adolescent↗
PubMed1987

Application of an immunoprecipitation procedure to the study of SV40 tumor antigen interaction with mouse genomic DNA sequences.

Simian Virus 40 (SV40) large T antigen is a DNA binding protein with high affinity for segments of the viral genome. To find out whether T antigen also binds to sequences of genomic cellular DNA we mixed T antigen and SAU 3 A restricted mouse DNA under stringent DNA binding conditions. Resulting protein-DNA complexes were immunoprecipitated using T antigen specific monoclonal or polyclonal antibodies. The DNA fragments in the immunoprecipitates were cloned in plasmid vectors. Four plasmid clones were selected for a detailed investigation of the inserted mouse DNA fragments. Nucleotide sequencing and DNase I footprint experiments showed that T antigen binds to sites in these fragments consisting of two tandemly oriented G(A)AGGC pentamers separated by AT rich spacers of different lengths. The cellular binding sites are very similar in their architecture to the SV40-DNA binding site I. The isolated cellular DNA fragments with T antigen binding sites occur only once or a few times in the mouse genome. Our data help to further define the structure of T antigen's DNA binding sites. The genetic functions of the isolated cellular DNA elements are not known.

Animals↗
PubMed1987

Baroreflex setting and sensitivity in normal subjects: effects of pharmacologic inhibition of the angiotensin I converting enzyme.

Arterial blood pressure, heart rate and the response of these hemodynamic parameters to exogenous norepinephrine were investigated in healthy volunteers (daily sodium intake of 150 mmol) during a control period and after a single oral dose of 5 mg of the angiotensin I converting enzyme (ACE) inhibitor ramipril (HOE 498). Norepinephrine was infused at doses of 0.1, 0.2 and 0.3 micrograms kg-1 min-1, each for 10 minutes, during control and 3 hours after ramipril administration. Exogenous norepinephrine induced a dose-dependent increase in mean arterial blood pressure from 76.4 +/- 0.9 mm Hg during control to 85.6 +/- 1.5, 92.2 +/- 1.8 and 98.4 +/- 2.4 mm Hg, respectively. Ramipril significantly affected the baroreceptor set point with a decrease in mean blood pressure (72.1 +/- 1.7 vs 76.4 +/- 0.9 mm Hg, p less than 0.01) in the presence of unchanged heart rate (71.7 +/- 0.9 vs 73.6 +/- 1.5 min-1). Baroreceptor sensitivity, estimated by the slope of the delta blood pressure versus delta heart rate relation, was not affected by ACE inhibition. Also, the pressor effect of exogenous norepinephrine was unchanged by converting enzyme inhibition. The present results show that ACE inhibition with ramipril in sodium-replete healthy volunteers induces a decrease in blood pressure that is not accompanied by changes in heart rate, pressor sensitivity to exogenous norepinephrine or baroreceptor sensitivity.

Adult↗