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Biomedical subjects

H Weiss

Publications and source records attributed to H Weiss.

At least 217 records · Page 12Linked to original sources
PubMed1990

Proliferation of cultivated cells from normal, preneoplastic and neoplastic human breast tissue--preliminary report.

The success of cultivation of epithelial cells from normal, neoplastic and preneoplastic tissues is reviewed. MCDB 170 medium with special supplements is useful for epithelial cell culture. The epithelial character was demonstrated by the reaction with 3 different monoclonal antibodies. Most cell populations from preneoplastic and neoplastic tissues were identified as fibroblasts. Cell proliferation as measured by cell doubling time, labeling index, flow cytometry did not differ between the tissue types examined. Only 3H-thymidine uptake showed an increased tendency in cells from preneoplastic and neoplastic tissues. The use of normal human breast epithelial cells for molecular biological studies is recommended.

Breast↗
PubMed1989

The pathway of the quinol/quinone transhydrogenation reaction in ubiquinol: cytochrome-c reductase of Neurospora mitochondria.

Ubiquinol: cytochrome-c reductase, isolated from Neurospora mitochondria as a protein/Triton X-100 preparation, and reconstituted into phospholipid membranes, catalyses the electron transfer from duroquinol to 2.3-dimethoxy-5-decyl-6-methyl-benzoquinone (decQ) on a myxothiazol-insensitive, but antimycin-sensitive, ping-pong pathway. Duroquinol reacts first to form the altered, reduced enzyme E'. This reaction is followed by dissociation of duroquinone making way for E' to bind decQ and convert it into decQH2.

Catalysis↗
PubMed1989

A family of mitochondrial proteins involved in bioenergetICS and biogenesis.

The respiratory chain complexes of mitochondria consist of many different subunits, of which only a few partake directly in electron transport. The functions of the subunits that do not contain prosthetic groups are largely unknown. The cytochrome reductase complex of Neurospora crassa, for examine, consists of nine different subunits, of which the peripheral membrane proteins I and II (ref.3) that are located on the matrix side of the mitochondrial inner membrane are the largest subunits devoid of redox centres. Significantly, a cytochrome reductase fraction lacking these two subunits was inactive in electron transfer, and in yeast mutants with defective genes for either of the two subunits, assembly of the reductase is disrupted. Most mitochondrial proteins are imported into the mitochondrion as precursor proteins, and two proteins are necessary for cleaving their presequences, namely the matrix processing peptidase (MPP) and the processing enhancing protein (PEP), the latter strongly stimulating the activity of the former. Temperature-sensitive yeast mutants, which are affected in PEP or MPP, accumulate precursors at the nonpermissive temperature. We report here that subunit I of the cytochrome reductase can be grouped as members of the same protein family.

Amino Acid Sequence↗
PubMed1989

A small isoform of NADH:ubiquinone oxidoreductase (complex I) without mitochondrially encoded subunits is made in chloramphenicol-treated Neurospora crassa.

In mitochondria of Neurospora crassa grown in the presence of chloramphenicol a small form of NADH:ubiquinone reductase is made in place of the normal electron-transfer-complex I. This smaller enzyme has a molecular mass of approximately 350 kDa and consists of (at least) 13 different subunits which are all synthesized in the cytoplasm. The complex I which is normally found in Neurospora has a molecular mass of approximately 700 kDa and consists of around 30 different subunits, of which at least six are made in the mitochondria. Immunoblotting and peptide mapping suggest that the subunits of the small enzyme are homologous to subunits of the large enzyme, one subunit might even be identical. The small and the large NADH:ubiquinone reductases have the same high-affinity binding site for NADH but the two enzymes differ in the affinity and inhibitor sensitivity of the ubiquinone-binding site. The possibility is discussed that the small NADH:ubiquinone reductase is primitive isoform of complex I.

Binding Sites↗
PubMed1989

Identification and electron microscopic analysis of a chaperonin oligomer from Neurospora crassa mitochondria.

A 7-fold symmetric particle has been identified in Neurospora crassa which is most probably the mitochondrial chaperonin. The particle, about 12 nm in diameter, appears in preparations of cytochrome reductase, and is shown to contain a 60 kd protein which cross-reacts with anti-GroEL antibodies. Results of STEM mass measurement suggest that the particle is composed of 14 subunits. A preliminary interpretation of the structure of the particle based on electron microscopy is given. Its quaternary structure and molecular weight are similar to those of the recently discovered family of particles called chaperonins, found in bacteria, chloroplasts and mitochondria.

Chaperonins↗
PubMed1989

[Metastases caused by fine needle puncture?].

Tumour cells appear spontaneously in the blood of tumour patients. However, the formation of metastases depends not only on the number of tumour cells, but also to a large degree on the defence status of the patient. According to the experiments presented here, fine needle puncture can slightly increase tumour cell migration. Tumour cells are carried through the puncture channel into the bloodstream; case reports show that in some cases the number of tumour cells mobilised in this manner may be sufficient to induce a metastatic growth at the site of puncture. However, practically all reported cases concerned advanced tumour stages. The puncture metastasis did not exercise any influence on the course of the disease or on the prognosis. The incidence of metastases in the puncture channel after fine needle biopsy of tumours of various organs is between 0.003 and 0.005% and is hence low. Nevertheless, indication for fine needle puncture of malignant processes should be considered very critically. However, if the use of the puncture leads one to expect therapeutic consequences that are of relevance for the patient, the doctor should not hesitate to employ this method which has a high informative value.

Biopsy, Needle↗
PubMed1989

[Organ manifestations of malignant lymphoma. Results of 10 years' sonographic follow-up of 550 patients].

Over a period of 10 years and by performing slightly more than 5,000 examinations, the incidence rate of organ infiltrations in case of malignant lymphomas was determined in 550 patients. 316 of these patients had non-Hodgkin lymphomas of low malignancy (NHLL), 127 non-Hodgkin lymphomas of high malignancy (NHLH) and 107 patients had lymphogranulomatosis. Liver infiltrations were detected in 30.9% of the patients with LG, in 31.5% of the patients with NHLH and in 13% of the patients with NHLL. In respect of histology, sonography had a sensitivity of 89 and a specificity of 95%. 17.8% of the patients with LG, 8.7% of those with NHLH and 6% of those with NHL had a nodular spleen infiltration; only 2 out of 21 patients of whom comparative histology was available had been falsely assessed negatively. In 2.8% of the patients with LG, 13.4% of those with NHLH and 5% of those with NHLL an infiltration of the gastrointestinal tract was seen. Compared with histological findings, sonography had a sensitivity of 85.7% and a specificity of 93.2%. Infiltrations of the pleura were more frequent in patients with lymphogranulomatosis (13.1%) than in patients with NHLH (7.8%) or NHLL (3.8%). The same phenomenon was seen in infiltrations of the pericardium (LG 10.3%, NHLH 8.7%, NHLL 2.8%). Infiltrations of thyroid, kidneys and urinary bladder are less frequent; the assessed rate of incidence is at the most 2%. Sonography is the imaging method of choice in the diagnosis and follow-up control of organ infiltrations in malignant lymphomas.

Follow-Up Studies↗
PubMed1989

Activation of potassium channels in renal epithelioid cells (MDCK) by extracellular ATP.

Extracellular ATP has been shown to stimulate transepithelial chloride transport in confluent Madin-Darby canine kidney (MDCK) cell layers and to enhance potassium conductance in subconfluent MDCK cells. The present study has been performed to test for the effect of extracellular ATP on channel activity in patches from subconfluent MDCK cells. Within 8 s, addition of extracellular ATP (10 mumol/l) leads to a sustained, but fully reversible, appearance of potassium-selective channels in cell-attached patches [increase of open probability from 0.03 +/- 0.02 (n = 10) to 0.50 +/- 0.07 (n = 6)]. With the use of pipettes filled with 145 mmol/l KCl, inwardly rectifying property of the channels is disclosed with a single-channel conductance of 65.7 +/- 3.1 pS (n = 9) at zero potential difference between pipette and bath and with a reversal potential of 75.4 +/- 2.0 mV (n = 5; pipette negative vs. reference in the bath). The open probability of the channels is not significantly modified by altering pipette potential from -50 mV, pipette positive, to 50 mV, pipette negative. At extracellular calcium activities of less than 10 nmol/l, ATP leads to a transient activation of channels. In conclusion, extracellular ATP activates inwardly rectifying potassium channels in the cell membrane of subconfluent MDCK cells. A sustained activation of the channels requires the presence of extracellular calcium and is probably mediated by increases in intracellular calcium.

Adenosine Triphosphate↗
PubMed1989

Fundus polaroid screening for diabetic retinopathy. Is one print per patient enough?

The CR3-45 NM Canon nonmydriatic fundus camera detects relevant diabetic retinopathy with high sensitivity. To determine whether examination of one eye per patient would suffice for screening purposes, 473 pairs of standard 45 degree fundus Polaroid prints obtained with the Canon camera were assessed from 167 patients with and 306 without diabetic retinopathy. On the basis of considering only one eye per patient, absence of retinopathy would have been diagnosed in 336 patients, with 9% of the diagnoses false negative. One hundred thirty-seven of the 167 patients with retinopathy in at least one eye would have been diagnosed correctly by considering one eye per patient (sensitivity 82%, specificity 100%). Thus, a standard 45 degree fundus Polaroid print from one eye per patient may suffice for screening purposes if the picture is free from diabetic abnormalities. Otherwise, both eyes should be examined immediately, and the patient should be referred to an expert ophthalmologist who specializes in diabetic retinopathy for confirmation of the diagnosis and staging of diabetic retinopathy status.

Adult↗
PubMed1989

DNA distribution pattern in chronic gastritis. I. DNA ploidy and cell cycle distribution.

DNA distribution patterns were flow cytometrically recorded in gastric biopsy specimens from patients with chronic gastritis (CG) and chronic atrophic gastritis (CAG). DNA aneuploidy was found in 3 of 58 patients with CG and in 7 of 82 patients with CAG. Cell cycle analysis disclosed significantly higher percentages of cells in S-phase and G2M-phase, respectively, in CAG than in CG. With regard to the proliferative activity the total CAG group could be partially differentiated by the degree of severity. CAG with total atrophy showed significantly higher percentages of cells in S-phase than CAG with mild and moderate atrophy. CAG without dysplasia showed lower percentages of cells in S-phase and G2M-phase than CAG with severe dysplasia (p greater than 0.05). The occurrence of intestinal metaplasia was correlated to a significantly higher percentage of cells in G2M-phase.

Adult↗
PubMed1988

[Fatal complication of fine-needle biopsy of the liver].

A 62-year-old woman with cirrhosis of the liver was suspected of also having a primary liver-cell carcinoma. After puncture of a circumscribed liver process with a biopsy fine-needle there occurred massive bleeding which could not be surgically stopped, and the patient died. This was the first fatal outcome among 2760 fine-needle punctures in the author's personal series (0.036%).

Biopsy, Needle↗
PubMed1988

Seizures following myelography with iopamidol.

Iopamidol, a water-soluble contrast medium, has been rarely associated with seizures. We describe 3 patients (from a series of 785) who had generalized tonic-clonic seizures after iopamidol myelography. Two of the patients underwent lumbar and one cervical myelography. There was a history of seizures in 2 patients, and the dose of iopamidol used in the patients who convulsed was high, ranging from 3,000 to 4,500 mg iodine. Despite the reported low incidence of complications with iopamidol, seizures may occur, especially in patients with previous seizures and also in those receiving higher doses of iopamidol.

Female↗
PubMed1988

Effects of serotonin on electrical properties of Madin-Darby canine kidney cells.

The present study has been performed to test for the influence of serotonin on the potential difference across the cell membrane (PD) of Madin-Darby canine kidney (MDCK)-cells. Under control conditions PD averages -48.6 +/- 0.6 mV (n = 98). Increasing extracellular potassium concentration from 5.4 to 10 and 20 mmol/l depolarizes the cell membrane by +6.3 +/- 0.6 mV (n = 6) and +14.1 +/- 1.0 mV (n = 12), respectively. The cell membrane is transiently hyperpolarized to -67.8 +/- 0.8 mV (n = 63) by 1 mumol/l serotonin. In the presence of serotonin, increasing extracellular potassium concentration from 5.4 to 20 mmol/l depolarizes the cell membrane by +26.4 +/- 1.0 mV (n = 11). 1 mmol/l barium depolarizes the cell membrane by +15.7 +/- 1.3 mV (n = 17) and abolishes the effect of step increases of extracellular potassium concentration from 5.4 to 10 mmol/l. In the presence of barium, serotonin leads to a transient hyperpolarization by -26.3 +/- 1.0 mV (n = 16). During this transient hyperpolarization, the cell membrane is sensitive to extracellular potassium concentration despite the continued presence of barium. 10 mumol/l methysergide hyperpolarize the cell membrane by -7.2 +/- 2.0 mV (n = 6). In the presence of 10 mumol/l methysergide, the effect of serotonin is virtually abolished (+0.4 +/- 0.9 mV, n = 6). 1 mumol/l ketanserin, a 5-HT2 receptor blocking agent, ICS 205-930, a 5-HT3 receptor blocking agent, and phentolamine, an unspecific alpha-receptor blocking agent, do not significantly modify the effect of serotonin. In the nominal absence of extracellular calcium, the effect of serotonin is markedly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗