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Biomedical subjects

M Weiss

Publications and source records attributed to M Weiss.

At least 541 records · Page 30Linked to original sources
PubMed1988

Giant cell tumor of the metatarsal.

The following is a report of a giant cell tumor of a metatarsal, description of treatment, and review of the literature. Giant cell tumors comprise approximately 5-8% of the primary bone tumors. Metatarsal bones are a very rare primary site of involvement. Clinically aggressive or benign behavior cannot be predicted histologically. Treatment should be aggressive, as in this case where en bloc resection and bone graft were performed. Results were excellent with 4 yr follow-up.

Adult↗
PubMed1988

[Protaminase activity of plasma. III. Role of conversion enzyme (kininase II) in protaminase activity of plasma].

Kininase I (carboxypeptidase N) and kininase II (angiotensin converting enzyme) were isolated from human plasma by gel filtration on Sephadex G 200, then separated and partially purified by ion exchange chromatography. These two partially purified enzymic preparations allowed us to demonstrate that protamine underwent an extensive degradation only when both kininases acted simultaneously. The effects of CoCl2, an activator, and of several inhibitors, amongst which captopril, suggest that the same enzymatic system is responsible for the in vitro protaminasic activity of diluted unfractionated plasma.

Carboxypeptidase B↗
PubMed1988

Nutritional copper intoxication in three German infants with severe liver cell damage (features of Indian childhood cirrhosis).

Three of the four children of two unrelated German families fell ill in the first year of life with severe hepatopathy leading to death in two of the children so far, after a progressive clinical course and severe hepatic failure. Laboratory and morphological investigations revealed a high concentration of copper in the liver and to a lesser degree in the kidneys and other organs. The liver architecture was severely altered by micronodular cirrhosis with toxic liver cell damage similar to that found in Indian childhood cirrhosis. Epidemiologically, copper intoxication of the drinking water was verified. The drinking water was obtained from wells via copper pipes. The copper content of the drinking water went as high as 3400 micrograms/l in the two families while water taken directly from the well showed normal content but had lowered pH (6.2). Both parents were clinically healthy, as was an older son who had not been exposed to copper intoxication during the first nine months of his life. Therefore, copper intoxication during the perinatal period appears to be a prerequisite for manifestation of the disease.

Chemical and Drug Induced Liver Injury↗
PubMed1988

Influence of ion-pair-formation on the pharmacokinetic properties of drugs. Part 3: Influence of hexylsalicylic acid on the pharmacokinetics of pholedrine.

Based on previous in vitro studies it could be shown that ion-pair-formation with the lipophilic hexylsalicylic acid (1) influences the pharmacokinetics of the hydrophilic drug pholedrine (2) which is ionized in all physiological media. After oral combination with 1 an increase of the AUC of 2 could be observed. This finding is due both to the increase of the absorption of 2 and to the decrease of the elimination of 2. After i.v. application the high biotransformation rate of 2 prevents an influence of 1.

Administration, Oral↗
PubMed1988

Metabolic studies in a patient with idiopathic hypophosphatemic osteomalacia.

Studies were conducted in a patient with idiopathic hypophosphatemic osteomalacia to delineate the roles of parathyroid hormone (PTH), vitamin D and renal tubular function. A 43-year-old woman presented with progressive skeletal pains resulting in severe incapacity. Workup revealed: hypophosphatemia with a low tubular maximal phosphate reabsorption per glomerular filtrate (TmP/GFR) of 1.05 mg/dl, normocalcemia, hypocalciuria, elevated alkaline phosphatase and glycinuria. PTH and urinary cyclic AMP (UcAMP) were normal, while calcitriol was low. Renal tubular acidosis or other transport defects were not present and no tumor was found. Biopsy was diagnostic for osteomalacia, and the patient responded to 1-alpha OHD3 and phosphate therapy. Hyperparathyroidism was ruled out by 1) normocalcemia persisting after 1-alpha OHD3 and calcium loading and 2) normal PTH and UcAMP challenged by phosphate supplements. Combined calcium and 1-alpha OHD3 administration resulted in hypercalciuria, decreased UcAMP and increased, but not corrected, TmP/GFR. These findings suggest that the osteomalacia was due to hypophosphatemia caused by a renal leak. PTH is only contributory to the phosphaturia. Low calcitriol level contributes to the osteomalacia directly and indirectly through impaired mineral absorption and, therefore, is also responsible for the hypocalciuria.

Adult↗
PubMed1988

[Behavior, personality and cardiovascular diseases].

An epidemiologic study of 1019 males, aged 45 to 59, included clinical and psychologic assessment, using Jenkins' questionnaire (JAS) and Freiburg personality identification questionnaire (FPI). Myocardial infarction survivors differed significantly from normal individuals by a number of psychological scores, such as depression, psychosomatic disturbances, anxiety, emotional lability. Anginal patients typically featured impulsiveness, psychosomatic disturbances, depression, anxiety, reserve, emotional lability. The examination of behavior determinants of arterial blood pressure in adolescents, based on cluster analysis, identified 3 groups of individuals with different behavioral syndromes. The clinical implication of these psychologic clusters was essential intercluster differences in terms of systolic and diastolic arterial blood pressure.

Adolescent↗
PubMed1988

Washout time versus mean residence time.

The relationship between washout time and mean residence time (MRT) of drug is evaluated for pharmacokinetic systems showing either convex disposition curves (bolus i.v. administration) or concave oral curves in a semilogarithmic plot. Generalizing the classical one-compartment approach bounds on the washout times (time for 63.2% or 90% of the dose to be eliminated) are derived and the importance of the distribution process of drug in the body as an influencing factor is emphasized. It is shown that under certain conditions a useful first approximation of MRT can be estimated from the cumulative amount excreted into urine up to some time t. Theoretical evidence is provided that in general a washout period of about 5 MRT should be sufficient for practical purposes.

Administration, Oral↗
PubMed1987

Anomalous uncoupling of photophosphorylation by palmitic acid and by gramicidin D.

Palmitic acid and gramicidin D at low concentrations uncouple photophosphorylation in a mechanism that is inconsistent with classical uncoupling in the following properties: (1) delta pH, H+ uptake, or the transmembrane electric potential is not inhibited. (2) O2 evolution is stimulated under nonphosphorylating conditions but slightly inhibited in the presence of adenosine 5'-diphosphate + inorganic phosphate (Pi). (3) Light-triggered adenosine 5'-triphosphate (ATP)-Pi exchange is hardly affected, and ATPase activity is only slightly stimulated. (4) ATP-induced delta pH formation is selectively inhibited. This characteristic uncoupling is observed only when the native coupling sites of the electron transport system are used for energization such as for methylviologen-coupled phosphorylation. With pyocyanine, which creates an artificial coupling site, 1000-fold higher gramicidin D and higher palmitic acid concentrations are required for inhibition, and the inhibition is accompanied by a decrease in delta pH. Moreover, comparison between photosystem 1 and photosystem 2 electron transport and the effects of membrane unstacking suggest that low gramicidin D preferentially inhibits photosystem 2, while palmitic acid inhibits more effectively photosystem 1 coupling sites. The inhibitory capacity of fatty acids significantly drops when the chain length is reduced below 16 hydrocarbons or upon introduction of a single double bond in the hydrocarbon chain. It is suggested that palmitic acid and gramicidin D interfere with a direct H+ transfer between specific electron transport and the ATP synthase complexes, which provides an alternative coupling mechanism in parallel with bulk to bulk delta microH+. The sites of inhibition seem to be located in chloroplast ATP synthase, photosystem 2, and the cytochrome b6f complexes.

Chloroplasts↗
PubMed1987

[Extra-pulmonary complications in Mycoplasma pneumoniae infections].

It is not rare that extrapulmonary complications and not pneumonia dominate the clinical picture in infections with Mycoplasma pneumoniae, as is illustrated by three cases. In the first, a young woman developed an acute, but ultimately completely reversible, polyradiculitis after a Mycoplasma pneumonia. The second patient sustained a thoracic transverse myelitis which regressed rapidly and completely under treatment with erythromycin and prednisone. In the third one, the Mycoplasma pneumonia was complicated by a generalized hypersensitivity vasculitis affecting many organs. A largely reversible renal vasculitis was demonstrated angiographically.

Adult↗
PubMed1987

Dietary fat in experimental nephrotic syndrome: beneficial effects of fish oil on serum lipids and, indirectly, on the kidney.

Three isocaloric diets with different fat composition were fed to rats for seven weeks after the production of nephrotic syndrome by adriamycin. The effects of feeding 3% and 14% fish oil were compared with those of feeding beef fat. At the fourth week of feeding the levels of triglycerides and cholesterol were lower in both fish oil fed groups. At the seventh week these levels, and the LDL cholesterol, were lower only in the 14% fish oil group. In rats fed beef fat, but not in those fed fish oil, there was a striking positive correlation of the four-week serum triglycerides and cholesterol with the seven-week serum creatinine level and with the degree of glomerular hyalinosis and endothelial swelling. The favorable effects of fish oil feeding on serum lipids may have a protective effect on the development of glomerular damage.

Animals↗
PubMed1987

Toroviridae: a proposed new family of enveloped RNA viruses.

The proposed family Toroviridae is characterized by enveloped, peplomer-bearing particles containing an elongated tubular nucleocapsid of helical symmetry. The capsid may be bent into an open torus, conferring a biconcave disk or kidney shape on the virion (largest diameter 120-140 nm), or straight, resulting in a rod-shaped particle (dimensions 35 X 170 nm). Morphogenesis occurs by the budding of preformed tubular nucleocapsids through membranes of the Golgi system and of the rough endoplasmic reticulum. Berne virus, which is proposed as the family prototype, contains a single strand of infectious positive-sense RNA, of Mr about 7.0 X 10(6), which is polyadenylated. The RNA is surrounded by the major nucleocapsid phosphoprotein (about 20 kDa) which, in turn, is enveloped by a membrane containing a major 22 kDa protein and a 37 kDa phosphoprotein. The viral peplomers measuring about 20 nm in length, carry determinants for neutralization and haemagglutination; the peplomers are formed by an N-glycosylated protein in the 75 to 100 kDa range. Six (to seven) subgenomic polyadenylated RNAs have been identified in infected cells, with Mr values of 2.6, 1.2, (1.0), 0.55, 0.35, 0.27 and 0.22 X 10(6). Torovirus replication requires some synthetic activity of the host cell. All toroviruses identified so far cause enteric infections and are probably transmitted by the faecal-oral route. Serological relationships between the equine, bovine and human viruses have been demonstrated.

Animals↗
PubMed1987

Hepatoma variants (C2) are defective for transcriptional and post-transcriptional actions from both endogenous and viral genomes.

A series of rat hepatoma cell lines was infected with a recombinant adenovirus bearing the rat albumin promoter. Transcription from this promoter was scored directly and was highest in FAO, the differentiated parent, undetectable in C2, a cell variant that has lost almost all hepatocytic characteristics, and high again in C2-Rev7, a 'revertant' cell line derived from C2 that has regained the ability to produce many proteins characteristic of hepatocytes. The endogenous albumin gene is not transcribed in C2 cells, and at a very low rate in C2-Rev7 cells, which accumulate endogenous albumin mRNA at close to normal amounts. Thus the C2-Rev7 'recovery' of albumin mRNA concentration for the endogenous gene is based mainly on post-transcriptional events while the ability of C2-Rev7 to transcribe the albumin promoter in the viral genome is based on a transcriptional factor(s). We also showed that the C2 phenotype included post-transcriptional effects for other genes: transcription of phenylalanine hydroxylase and phosphoenolpyruvate carboxykinase mRNA sequences continue in C2 at rates equivalent to FAO but these C2 cells have no mRNA for these proteins while FAO does. In addition, C2 cells transcribed certain early adenovirus transcription units (E2 and 4) as well as FAO cells but accumulated E2 mRNAs poorly if at all. The changes that led to the C2-Rev7 cell line produced a return to normal of the ability to accumulate these viral mRNAs. Thus a major event in the C2 to C2-Rev7 transition involves post-transcriptional processes as well as the ability to transcribe the albumin promoter positioned in the virus genome.

Adenoviridae↗
PubMed1987

Long-term evaluation of five biomaterials for angioplastic enlargement of the pulmonary artery in a young dog model.

In 45 young dogs an enlargement angioplasty of the left pulmonary artery was performed using patches made from one of three autologous materials (jugular vein, unmodified pericardium, and glycerolized pericardium) or from two heterologous materials (lyophilized human dura mater and modified bovine carotid artery). Catheterization and angiographic studies performed 5 to 6 months after the operation showed that all patched vessels had remained patent, except in three dogs which had received heterologous implants. The animals were killed 5-24 months after operation (mean weight increase: 84%), and the implants were studied by optical microscopy and morphometry, scanning and transmission electron microscopy, and indirect immunofluorescence with antidog Factor VIII rabbit antiserum. The two heterologous tissues exhibited limited biocompatibility, as estimated from 10 criteria obtained at histologic studies. Conversely, all three autologous biomaterials were characterized by infiltration of noninflammatory cells, near-complete endothelialization, and neosynthesis of structural proteins; infectious foci were very rare or absent. These results suggest that autologous tissues, although deendothelialized at the time of implantation, constitute the most suitable material for patch angioplasty, as far as endothelial triggering, cellularity and resistance to infection are concerned.

Animals↗