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Biomedical subjects

J Lohmann

Publications and source records attributed to J Lohmann.

At least 19 recordsLinked to original sources
PubMed1999

A head-activator binding protein is present in hydra in a soluble and a membrane-anchored form.

The neuropeptide head activator plays an important role for proliferation and determination of stem cells in hydra. By affinity chromatography a 200 kDa head-activator binding protein, HAB, was isolated from the multiheaded mutant of Chlorohydra viridissima. Partial amino acid sequences were used to clone the HAB cDNA which coded for a receptor with a unique alignment of extracellular modules, a transmembrane domain, and a short carboxy-terminal cytoplasmic tail. A mammalian HAB homologue with identical alignment of these modules is expressed early in brain development. Specific antibodies revealed the presence of HAB in hydra as a transmembrane receptor, but also as secreted protein, both capable of binding head activator. Secretion of HAB during regeneration and expression in regions of high determination potential hint at a role for HAB in regulating the concentration and range of action of head activator.

Amino Acid Sequence↗
PubMed1998

Time-dependent changes in the density and hemoglobin F content of biotin-labeled sickle cells.

Sickle red blood cells (RBC) are subject to a number of important cellular changes and selection pressures. In this study, we validated a biotin RBC label by comparison to the standard 51Cr label, and used it to study changes that occur in sickle cells as they age. Sickle RBC had a much shorter lifespan than normal RBC, but the two labels gave equivalent results for each cell type. A variable number of sickle, but not normal, RBC disappeared from the circulation during the first few hours after reinfusion. The number of biotinylated sickle reticulocytes was decreased by 50% after 24 h and 75% after 48 h, with a gradual decrease in the amount of reticulum per cell. The labeled sickle cells exhibited major density increases during the first 4-6 d after reinfusion, with smaller changes thereafter. A small population of very light, labeled sickle RBC was essentially constant in number after the first few days. Fetal hemoglobin (HbF) content was determined in isolated biotinylated sickle RBC after reinfusion, allowing an estimate of lifespan for RBC containing HbF (F cells) and non-F cells. The lifespan of sickle biotinylated RBC lacking HbF was estimated to be approximately 2 wk, whereas F cells survived 6-8 wk.

Anemia, Sickle Cell↗
PubMed1997

Systematic isolation of peptide signal molecules regulating development in hydra: LWamide and PW families.

To isolate new peptide signal molecules involved in regulating developmental processes in hydra, a novel screening project was developed. Peptides extracted from the tissue of Hydra magnipapillata were systematically purified to homogeneity using HPLC. A fraction of each purified peptide was examined by differential display-PCR for its ability to affect gene expression in hydra. Another fraction was used to determine the tentative structure using an amino acid sequence analyzer and/or a mass spectrometer. Based on the results, peptides of potential interest were selected for chemical synthesis, followed by confirmation of the identity of the synthetic with the native peptides using HPLC. Using this approach, 286 peptides have been isolated, tentative amino acid sequences have been determined for 95 of them, and 19 synthetic peptides identical to native ones were produced. The 19 synthetic peptides were active in a variety of biological tests. For example, Hym-54 stimulated muscle contraction in adult polyps of hydra and sea anemone, Anthopleura fuscoviridis, and induced metamorphosis of planula, the larval stage, into polyps in a marine hydrozoan species, Hydractinia serrata. Another peptide, Hym-33H, inhibited nerve cell differentiation in hydra and induced tissue contraction in planula of Hydractinia serrata. The evidence obtained so far suggests that hydra contains a large number (>350) of peptide signal molecules involved in regulating developmental or other processes in cnidaria. These peptides can be isolated and their functions examined systematically with the new approach developed in this study.

Amino Acid Sequence↗
PubMed1993

[Liver cirrhosis and chronic hepatic porphyria].

Chronic hepatic porphyrias (CHP) are associated with different degrees of liver damage. They range from minimal histological changes to cirrhosis and primary liver carcinomas. Forty patients with early stages of porphyrias were compared to 85 patients with clinically manifest porphyrias, Porphyria cutanea tarda. This comparison resulted in the fact that cirrhosis occurred more often in early (or latent) stages (65%) than in PCT (31%) confirmed by laparoscopy. Thus the severity of the liver disease does not depend on the duration and intensity of cutaneous symptoms or pathobiochemical syndromes but they more often depend on the long-term influence of so-called trigger factors, among them above all alcohol and iron overloading. We conclude that the proof of latent CHP has an index function for severer liver damage.

Female↗
PubMed1987

Concentration of fibronectin and granulocyte elastase in plasma of patients with systemic connective-tissue diseases.

The concentration of granulocyte elastase-alpha-1-protease inhibitor (E-AT) complex in plasma is enhanced in inflammatory processes, e.g. in septicaemia and rheumatoid arthritis, being an expression of granulocyte activation during inflammatory response. In the present study we measured E-AT and fibronectin in the plasma of 46 patients with various connective-tissue diseases in relation to the course of the disease. In about 50% of the cases, E-AT was found to be elevated to 2-3 times the normal concentrations, in relation to increasing serum content of C-reactive protein. In follow-ups over 2 years, an elevation of E-AT and a decreasing fibronectin in plasma was found in patients with activated disease. Without relation to other parameters used in connective-tissue diseases, fibronectin was found to be diminished below the normal range in 7 patients with systemic lupus erythematodes and 1 patient with overlapping syndrome. Our results indicate that the concentration of E-AT and fibronectin in plasma may be helpful parameters for judging the activity of connective-tissue diseases.

Adolescent↗
PubMed1985

[Liver lesions induced by dihydralazine and propranolol].

The antihypertensive drugs dihydralazine and propranolol can produce identical liver injuries which must be distinguished clinically and morphologically from acute viral hepatitis. In 19 cases selected from our biopsy file during the last two years, clinical and morphological findings suggested that the liver injury diagnosed by light microscopy had been caused by an adverse reaction to dihydralazine and/or propranolol. In order to establish a causal relation the lymphocyte proliferation test (LPT) was performed with dihydralazine in 11 cases. Positive results were observed in 9 cases, demonstrating an etiologic role for dihydralazine in liver injury in these cases. The dihydralazine and/or propranolol induced liver injury consisted mainly of drug-induced hepatitis with confluent (bridging) necrosis. Different findings were observed in three cases: In two of these drug-induced hepatitis with confluent necrosis was observed together with eosinophilic cholangio-cholangiolitis. In one other case the histologic changes corresponded to drug hepatitis resembling viral hepatitis. Each of the three cases showed conspicuous centrolobular cholestasis, a feature which is unusual in drug-induced hepatitis with confluent necrosis irrespective of serum bilirubin levels. In one third of our cases we found morphological features of hypersensitivity reactions in the liver biopsies. Considered together with the results of LPT these features emphasize the role of cell mediated immune reaction in the mechanism of liver injury caused by dihydralazine and/or propranolol.

Biopsy↗
PubMed1984

The influence of paracetamol on the hepatic biosynthesis of lecithin.

In paracetamol induced liver injury changes in the phospholipid components of microsomal membranes are usual. Direct incubation of paracetamol with subcellular fractions of human liver specimens did not alter the biosynthesis of lecithin. Preincubation of liver slices with paracetamol led to an increased synthesis of lecithin. The presence of intact cells and the integrity of hepatocellular function seem to be a prerequisite for the poisoning effects in vitro.

Acetaminophen↗
PubMed1984

The rare occurrence of a radiation-induced osteosarcoma in the clavicule after treatment of thyroid cancer.

The authors report on a postirradiation osteosarcoma of the clavicule in a patient treated for thyroid cancer. The total absorbed dose to the right clavicule was estimated 149 Gy (60 Co and 18 MeV elektron beam). The findings are demonstrated on plain radiographs, CT-scan and bone scintigraphy. The literature on this subject is reviewed and the possible pathogenesis discussed.

Adenoma↗
PubMed1983

Drug intoxication: influence of hemoperfusion on human plasma fibronectin.

Fibronectin is a glycoprotein belonging to the opsonic system and able to mediate phagocytosis by the reticuloendothelial system (RES). Severe intoxications are often followed by a diminished capacity of RES-clearance. Patients with severe drug intoxications have lower concentrations of fibronectin in plasma than healthy persons. Charcoal hemoperfusion lowers plasma fibronectin by an average of 4.7 mg/dl. Initial values below 15 mg/dl did not undergo a significant decrease in the case of hemoperfusion. Regarding these findings, determination of plasma fibronectin seems a useful parameter for monitoring RES function during treatment of drug-intoxicated patients by hemoperfusion.

Adolescent↗
PubMed1983

[Treatment of acute liver failure by plasmapheresis].

Repeated plasmaphereses were done in 7 patients with acute hepatic failure (5 of them with coma stage IV and two with stage III). Acute liver insufficiency was induced by fulminant viral hepatitis in 4 cases, by drugs in one case, and was caused by a dystrophic exacerbation of liver cirrhosis in two further cases. Four of the 7 treated patients have survived. Beginning improvement of hepatic function was evidenced by an increase of factor VII and prothrombin in plasma. Significant lowering of bilirubin could be observed in all cases. While ammonia values decreased continuously in the four successfully treated patients while on plasmapheresis, the opposite behaviour was observed in the decreased patients. The influence of plasmapheresis on the pathologically altered aminoacid pattern in hepatic coma was investigated in two patients: Before treatment clearly to excessively increased values of methionine and aromatic aminoacids (phenylalanine and tyrosine) were seen. Branched-chain aminoacids leucine, isoleucine and valine were normal to moderately decreased. After termination of plasmapheresis methionine and aromatic aminoacids were significantly lower, branched-chain aminoacids were slightly below the initial values. Improvement of consciousness correlated with increase of the quotient (val+leu+ile)/(phe+tyr).

Acute Disease↗
PubMed1983

[Guillain-Barré polyradiculitis in acute viral hepatitis type B--case report].

A polyneuritis of the Guillain-Barré type developed in a 29 year-old female patient during the icteric stage of viral hepatitis B. The main symptoms were diffuse paresthesias and increasing motor weakness of the limbs, ending up in paralysis of the legs. The analysis of the CSF (albumin raised, cell count normal) and electroneurographic findings were diagnostically reaffirming. The patient was given prednisolone. All symptoms disappeared within two months.

Acute Disease↗