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Biomedical subjects

A Beyer

Publications and source records attributed to A Beyer.

At least 73 records · Page 4Linked to original sources
PubMed1991

PAS1, a yeast gene required for peroxisome biogenesis, encodes a member of a novel family of putative ATPases.

PAS genes are required for peroxisome biogenesis in the yeast S. cerevisiae. Here we describe the cloning, sequencing, and characterization of the PAS1 gene. Its gene product, Pas1p, has been identified as a rather hydrophilic 117 kd polypeptide. The predicted Pas1p sequence contains two putative ATP-binding sites and reveals a structural relationship to three other groups of proteins associated with different biological processes such as vesicle-mediated protein transport (NSF and Sec18p), control of cell cycle (Cdc48p, VCP, and p97-ATPase), and modulation of gene expression of the human immunodeficiency virus (TBP-1). The proteins share a highly conserved domain of about 185 amino acids including a consensus sequence for ATP binding. We suggest that these proteins are members of a novel family of putative ATPases and may be descendants of one common ancestor.

Adenosine Triphosphatases↗
PubMed1991

Application of scanning electron microscopy (SEM) and microbead techniques to study the localization of p24 and p18 antigens of HIV-1 on the surface of HIV-1-infected H9-lymphocytes.

Immunofluorescence staining techniques at present, when applied to follow the expression of HIV-1-specific antigens on infected cells, only give the information that the antigens detected are localized in the outer region of the membrane of the infected cell. We therefore set up a procedure using magnetic polystyrol particles coated with antibodies specific for the HIV-1 antigens under study, in combination with scanning electron microscopy. We were able to demonstrate that p24 and p18 structural antigens are clearly expressed on the surface of HIV-1-infected H9 lymphocytes. This means that there was no steric hindrance for structures of cell-like size specific for HIV-1 antigens to interact with their target antigens. Other antigens may be hidden in membrane structures and are therefore inaccessible, for example, to the beads used here, which were of a similar size to antigen-specific cells in vivo. The results of this model system must be seen with respect to the interaction of antigen-specific cell-mediated immunity with full antibody-dependent cellular cytotoxicity, or without cytotoxic T lymphocytes, the mediator function of antibodies.

Animals↗
PubMed1990

Total gastrectomy and oesophagojejunostomy--a prospective randomized trial of hand-sutured versus mechanically stapled anastomoses.

Eighty patients undergoing total gastrectomy for malignant disease were entered into a prospective randomized study, comparing anastomoses constructed mechanically (staples) with hand-sewn (single layer Maxon) anastomoses. The groups were matched with respect to clinical features, medical risk factors and were staged for tumour. Only one anastomotic leak was observed after operation and this was in the group of stapled anastomoses. One patient died in each group (owing to cardiac infarction and multiorgan failure). Operating time, morbidity and hospital stay showed no significant differences between groups. These results indicate that hand-sewn and mechanically stapled oesophagojejunostomy anastomoses allow the same high standard of performance.

Adenocarcinoma↗
PubMed1989

Trypsin sensitivity of several human rhinovirus serotypes in their low pH-induced conformation.

Five serotypes of human rhinovirus (HRV) were examined for sensitivity to trypsin at physiological pH, HRV1A, HRV2, and HRV14 were found to be resistant whereas in serotypes HRV49 and HRV89 degradation of VP2 was observed. However, exposure to low pH followed by neutralization, a treatment which causes irreversible conformational changes in the capsid, led to rapid cleavage by trypsin of VP1 in HRV1A, HRV2, and HRV49 at defined sites followed by degradation of VP2. In the case of HRV2, the cleavage site in VP1 was determined by direct protein sequencing and was shown to occur between Arg260 and Thr261, close to the C-terminus. HRV49 behaves similarly to HRV2 as expected from extensive sequence similarity in this region, whereas VP1 in HRV1A is most probably cleaved at a site closer to the C-terminus than that in HRV2. Although HRV14 contains the same amino acid pair present in HRV2 and HRV49, it was not cleaved under these conditions. HRV89, which lacks a basic residue at the corresponding position, was also insensitive. Examination of the cleavage site on the three-dimensional structural map of native HRV2 reveals that it is most probably buried inside the capsid and thus not accessible. Structural rearrangements of the viral capsid are thus necessary to account for the cleavage observed after low pH treatment.

Capsid↗
PubMed1988

[The equilibrium of nitrogen, potassium and phosphate and renal excretion of creatinine and creatinine over the course of 3 weeks following severe trauma].

In 19 patients after accidental trauma and with intact renal function during an observation time of 21 days we found a cumulated negative balance of nitrogen (N), phosphate (P) and potassium (K) amounting to a mean of 214g, 357 and 447 mmol, respectively. Median daily potassium balance was positive on day 2 to 5 and this was interpreted as an increased extrarenal potassium deposition due to increased levels of circulating catecholamines. Median renal creatinine excretion was about 120% of predicted normal till day 10 and continuously decreased thereafter to values lower than predicted normal. Three patients did not show creatinuria (greater than 200 mg/day) during the whole observation time. In 15 patients after a "free interval" with a mean duration of 7 days creatinuria frequently developed rather quickly and maximal excretion of creatine was as high as 4 g/day. In 7 patients creatinuria persisted to the end of the 21 days observation time. During the phase of creatinuria the median cumulated excretion of creatine amounted to 14.4 g. The "free interval" of creatinuria after severe trauma is remarkable. Most of the N, K and P, which is lost from the body during this time obviously stems from tissues other than sceletal muscle. During the phase of creatinuria, however, the negative balance of N, K and P seems to be mainly due to muscle wasting. Hypophosphatemia was prominent during the first 5 days after trauma and obviously was caused by a decrease in renal phosphate threshold (TmPO4/GFR). The underlying mechanism of this primary change in renal function after severe trauma could not yet be identified.

Adolescent↗
PubMed1988

[Water-electrolyte balance and kidney function for 3 weeks following severe trauma].

A study on water-electrolyte metabolism and renal function was performed in 32 patients (mainly young to middle-aged males) over three weeks after severe accidental trauma (mainly brain trauma), who did not suffer from acute renal failure. With a mean water input of 4 l/day the difference of water input and urine volume was positive over the whole observation time. Patients had a mean osmolar excretion of 1800 mosm/day which was twice normal and was mainly caused by a high urea excretion. They were almost invariably in the state of antidiuresis and achieved unusually high values for negative free-water clearance around 2 ml/min. This, however, was adequate in terms of normotonicity of body water. Cumulated sodium balance over 21 days was negative and, on the average, amounted to minus 440 mmol. The median value for creatinine clearance was in the range of predicted normal (156 ml/min.) between day 5 and 10 and a little less before and thereafter. We frequently observed an elevation of creatinine clearance to 120-150% of normal. Renal clearance of urea was around 100 ml/min. during the phase of maximal protein catabolism. Therefore the reasonable increases in urea production up to a mean of 60 g/day resulted only in moderately elevated levels of plasma urea (40-50 mg/100 ml). In 14 patients we performed a total of 83 measurements of plasma volume (Evans-Blue). In patients with intact renal function mean plasma volume amounted to 110% normal. This, in combination with a reduced red all volume on the average, resulted in mild hypovolaemia (blood volume about 90% of predicted normal).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1983

Endogenous prostaglandin F2 alpha in the hyperdynamic state of severe sepsis in man.

Nine surgical patients underwent haemodynamic and respiratory monitoring during the course of severe sepsis. Endogenous PGF2 alpha levels in mixed venous and arterial plasma were measured. Results indicate pulmonary net release of PGF2 alpha, since arterial levels (1252 +/- 119 pg/ml) are significantly higher than mixed venous ones (824 +/- 89 pg/ml) in full-pronounced hyperdynamic septic shock. By contrast, the inactive metabolite KH2PGF2 alpha was found in lowest concentrations during shock (368 +/- 72 pg/ml) which suggests impaired pulmonary degradation. It is concluded that circulating PGF2 alpha is a marker of stimulated prostaglandin production in severe human sepsis.

Adolescent↗
PubMed1983

Ultrastructural analysis of the ribonucleoprotein structure of nascent hnRNA.

Active transcription units are visualized in the electron microscope and the ribonucleoprotein structure of nascent transcripts is analyzed by the technique of RNP fibril mapping. This ultrastructural approach has demonstrated that the nonrandom RNP structure observed is correlated with, and perhaps mediates, a specific RNA processing event.

Adenoviruses, Human↗
PubMed1983

Metabolism of phosphate and calcium after severe accidental trauma.

Hypophosphatemia is a common finding during the first 4-5 days after severe accidental trauma. We demonstrated that hypophosphatemia after trauma is caused by a definite decrease in renal phosphate threshold (TmPO4/GFR), that is the theoretical plasma phosphate concentration at which all of the filtered phosphate is reabsorbed by the renal tubules and renal excretion of phosphate is close to zero. We speculated that the decrease in renal phosphate threshold could be due to an increased activity of PTH which in turn could be the result of ionized hypocalcemia. In 7 patients with severe and in 8 patients with moderate trauma, however, we found ionized calcium and PTH levels to be within normal limits. Total plasma calcium was below normal (1.90-2.00 mmol/l) up to 20 days after trauma, probably due to a decreased plasma albumin concentration (25-30 g/l). We conclude, that ionized hypocalcemia and consecutive stimulation of PTH is not the cause of decreased renal phosphate threshold after severe accidental trauma.

Adolescent↗
PubMed1982

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH)--treatment with lithium.

Two patients with SIADH after brain trauma are described. Features of SIADH are "inappropriate" antidiuresis and excessive natriuresis with negative sodium balance resulting in hyponatremia and plasma hypoosmolality which may lead to cerebral dysfunction. Oral lithium carbonate was beneficial in both patients. With plasma levels of lithium around 1 mmol/l a temporary impairment of renal concentrating ability and antinatriuresis with normalization of plasma sodium and plasma osmolality was observed. The SIADH subsided about 4 months after the original trauma, long after gross neurological symptoms had resolved.

Accidents, Traffic↗
PubMed1982

[Acute neurological complications following intrathecal fluorescein injection (author's transl)].

This report describes two cases of grand mal seizures following intrathecal injection of fluorescein to delineate CSF-leakage. Recurrent phases of apnea necessitated artificial ventilation in one case. The results of CSF and serum investigations are discussed as well as EEG and EMG findings. As fluorescein has proved to be a potentially epileptogenic drug, its use for patients with a past history of seizures should be very carefully considered. All patients having received intrathecal fluorescein should be kept under observation for at least 4 to 6 hours.

Dura Mater↗
PubMedDate not supplied

[Spiro-ergometric studies after corrective surgery of tetralogy of Fallot].

Treadmill exercise electrocardiography and spirometry was recorded in 61 patients (aged from 5 to 23 years) who underwent corrective surgery for tetralogy of Fallot. The Bruce-protocol and a modified interval-protocol were compared to find out their ability to induce arrhythmias. Supraventricular arrhythmias were predominantly provoked by the interval-protocol while maximal exhaustion is often necessary for inducing ventricular arrhythmias which we found in 23% of our patients. Most of them were seen in the periods of recovery between or after the exercise. We propose a combination of both protocols, which will be compared with established forms of exercise-testing in further studies. The results of rhythm analysis of consecutive exercise tests in one patient after surgical repair could possibly be compared by using an "arrhythmia score" which tries to indicate the severity of different forms of arrhythmias. The values of maximal heart rate, oxygen consumption and endurance time recorded at maximal exercise (Bruce-protocol) were about 15% lower than correspondent values of healthy persons found by other authors.

Adolescent↗