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Biomedical subjects

R Gross

Publications and source records attributed to R Gross.

At least 397 records · Page 22Linked to original sources
PubMed1979

Elemental composition of platelets. Part I. Sampling and sample preparation of platelets for trace-element analysis.

Sampling of platelets for trace-element analysis poses special problems: obtaining adequate sample material, achieving a sufficient cell purity, preserving viability (integrity), correcting for trapped plasma, and controlling contamination. We used a blood-cell separator for the primary isolation of platelets from blood, and differential centrifugation in natural plasma to further isolate them. The pyrimidopyrimidine RA233 was used as a stabilizer to maintain viability. 131I-labeled human serum albumin was used to estimate trapped plasma. Contamination was controlled by using five-times-distilled water to simulate donor's blood in the system and by comparing three fractions: the serum, the first portion of the platelet-rich plasma, and the supernatant plasma after the final centrifugation. Neutron activation analysis was used for the elemental analysis. A single differential centrifugation of the platelet-rich plasma from the blood-cell separator at 400 x g for 8 min was optimum (mean mass fractions:erythrocytes/platelets less than 5 mg/g and leukocytes/platelets less than 20 mg/g). The trapped plasma in the wet platelet samples amounted to about 0.40 g/g. No appreciable contamination from the sampling system was found for the elements Ag, Cd, Co, Cr, Cs, Cu, Fe, Mo, Rb, Sb, Se, and Zn.

Blood Platelets↗
PubMed1979

Elemental composition of platelets. Part II. Water content of normal human platelets and measurements of their concentrations of Cu, Fe, K, and Zn by neutron activation analysis.

We determined the elements Cu, Fe, K, and Zn in normal human platelets by neutron activation analysis. The platelets were obtained from seven donors and treated as described in Part I. The elemental composition is expressed on a wet-weight basis for plasma-free platelets. The following results were obtained (+/- values are 1 SD); "Pure" platelets: trapped plasma = 378 +/- 35 mg/g, water content = 715 +/- 15 mg/g, mean weight of the single platelet (by two different methods) = 9.9 +/- 1.1 pg and 11.2 +/- 1.7 pg, K = 4.39 +/- 1.06 mg/g, Zn = 49.23 +/- 10.97 microgram/g, Fe = 12.28 +/- 2.94 microgram/g, and Cu = 1.39 +/- 0.25 microgram/g. "Impure" platelets: trapped plasma = 349 +/- 31 mg/g, water content = 736 +/- 12 mg/g, K = 3.26 +/- 0.78 mg/g, Zn = 35.71 +/- 7.99 microgram/g, Fe = 17.11 +/- 5.10 microgram/g, and Cu = 1.39 +/- 0.21 microgram/g. To our knowledge, no data on Fe and Cu in platelets have hitherto been reported.

Blood Platelets↗
PubMed1979

Catabolism of low-molecular-weight hydroxyethylated amylopectin in man. I. Changes in the circulating molecular composition.

Intravascular persistence concomitant with changes in the circulating molecular composition were determined in six fasted normal men dosed with 400 ml of 14% LMW-HES (a new plasma expander). The concentration of LMW-HES in serum fell to half its peak value in 3.9 +/- 1.1 (S.D.) hr, whereas serum levels of glucose remained elevated throughout the 12 hr postinjection fasting period. The LMW-HES recovered from the intravascular space was shown by gel filtration on a column of Sepharose CL-4B to be a narrower molecular size distribution (less polydispersion) than the injected material. The ratio of Kav . urine/Kav . injected solution was 1.34. At 30 min after injection, however, the ratio of Kav . urine/Kav . serum was 1.20, and by 24 hr, the value was 1.15. Overall, changes in the molecular distribution in the bloodstream between the end of the infusion period and 24 hr later were small. The results suggest that the intravascular catabolism of LMW-HES may occur in two distinct phases: a rapid initial degradation, followed by a more gradual elimination influenced by the MS of the injected material.

Adult↗
PubMed1978

The measurement of pulmonic valve area by angiocardiographic and hemodynamic methods.

The validity of angiocardiographic measurements in assessing the severity of pulmonic valve stenosis was determined. The pulmonic valve orifice area was measured in the lateral projection on cineangiocardiographic films in 24 patients with valvar pulmonic stenosis. The valve orifice area was also obtained in the same patients by the Gorlin and Bache formulae. The right ventricular output value required for insertion in these formulae was obtained by angiocardiographic right ventricular volume measurement and by the Fick method. The correlation between the directly measured valve orifice area and the area calculated using the Fick principle and the Bache formula was 0.80. The substitution of angiocardiographically measured right ventricular stroke volume for the Fick value gave a correlation of 0.82. The results support validity of employing direct angiocardiographic measurements of pulmonic valve orifice area and angiocardiographic right ventricular volume measurements for quantitative assessment of the severity of pulmonic valve stenosis. The angiocardiographic methods thus represent an alternative to the Fick technique which can be used in conditions where the Fick method cannot be expected to give valid results.

Adolescent↗
PubMed1978

[Computer-assisted diagnosis of haematological disease in hospital patients (author's transl)].

A system of computer-assisted diagnosis is described which, in analogy to conventional diagnosis, takes into account both logical and statistical factors. The arrangement of such a system makes it clear that, after a period of successful use in specialist branches of medicine, a phase of less spectacular success has occurred which, however, provides the conditions for including larger areas of medicine in computer-assisted diagnosis. These systems are likely to conform more closely to the needs of the doctor than previous ones. Whether they can be used in non-hospital practice would depend largely on whether the questions put to the system by the doctor do not take more time and answers can be given in short, easily understandable form. The best type of answer as well as the transmission of information can be discovered empirically. The differential diagnostic level of computer-assisted diagnosis is, according to present experience, quite satisfactory but can be further improved. This development is greatly helped by continuing increases in the speed of calculators and their data storage capacity.

Diagnosis, Computer-Assisted↗
PubMed1978

Roles of insulin and glucose in the regulation of plasma FFA in the duck. I. In the absence of pancreatic glucagon.

The present study was undertaken to determine how free fatty acid (FFA) release by adipose tissue can occur in the absence of pancreatic glucagon, the most potent lipolytic hormone in the duck. Two possible explanations have successively been investigated. Replacement therapy experiments showed that glucose uptake was implicated in the phenomenon; indeed, when pre-operative insulin and glucose levels were restored after total pancreatectomy, plasma FFA progressively fell to a level significantly lower than the pre-operative value. The same effect was observed when the ducks were kept in a continuous state of hyperglycaemia, whereas "normal" levels of insulin or glucose alone were shown to be ineffective. On the other hand a compensatory mechanism for the lack of glucagon, by other lipolytic agents [with the intestine or the anterior pituitary as possible sources] has been excluded by associating the removal of these two organs with pancreatectomy. These experiments suggest that the lack of pancreatic glucagon induced by total pancreatectomy is essentially masked by a failure in glucose uptake due to the operation.

Animals↗
PubMed1978

A prospective study of enteropathogenic Escherichia coli in endemic diarrheal disease.

The rate of isolation of Escherichia coli belonging to the traditional serotypes enteropathogenic for infants was studied prospectively in two groups. Group 1 consisted of children with diarrhea and of controls without gastrointestinal disease who were matched for age and inpatient or outpatient status. Group 2 consisted of families entered in a prospective study of rotavirus infections. In group 1 enteropathogenic Escherichia coli were found in 13 (6%) of 220 children younger than 12 months of age and in nine (6%) of 143 children 12--35 months of age, all of whom had diarrhea. Enteropathogenic E. coli were found in only one of an equal number of matched controls (P = 0.002 and 0.004, respectively). In group 2 enteropathogenic E. coli were present in seven (18%) of 38 specimens obtained during diarrheal episodes, as compared with five (1%) of 492 specimens obtained when there was no diarrhea (P less than 0.001). The enteropathogenic E. coli isolated were not enterotoxigenic. The most common serogroup was O111, but many different O:H serotypes were detected. Thus, the association of enteropathogenic E. coli with endemic diarrhea was significant, even though no enteropathogenic mechanism was apparent.

Adolescent↗
PubMed1978

Angiographic features of carcinoid heart disease.

Cineangiocardiograms from 2 patients with carcinoid syndrome and cardiac involvement were reviewed. Gross and microscopic pathology specimens were available for 1 case. Both patients exhibited tricuspid valvar stenosis and insufficiency. The area of the pulmonic valve was similar in both with narrowing of the annulus and tapering toward the valve of the proximal pulmonary artery and the subvalvar right ventricular outflow tract, producing an hourglass appearance, which the authors feel is characteristic of this disease.

Angiocardiography↗
PubMed1978

Platelet metabolism.

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Adenosine Diphosphate↗