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Biomedical subjects

B Koch

Publications and source records attributed to B Koch.

At least 127 records · Page 7Linked to original sources
PubMed1991

In vitro effects of an imidazole antifungal, prochloraz, on spectral and catalytic properties of microsomal cytochromes P-450.

1. The imidazole antifungal agent, prochloraz, elicited type II spectral interactions with microsomal cytochromes P-450 from rats pretreated with phenobarbital (PB), 3-methyl-cholanthrene (MC) and dexamethasone (DEX). 2. Prochloraz interacts strongly with type I binding sites of both PB- and DEX-induced cytochromes P-450 and to a lesser extent with cytochromes P-450 from MC-induced rats. 3. The antifungal derivative was a more potent inhibitor of the troleandomycin-nitrosoalkyl-cytochrome P-450 complex formation in DEX-induced microsomes than of the isosafrole-carbene-cytochrome P-450 complex formation in MC-pretreated rats. 4. Prochloraz is a strong inhibitor of the cytochrome P-450-dependent mixed-function oxidases in rat liver microsomal preparations.

Animals↗
PubMed1990

[Familial nonneoplastic inappropriate thyrotropin secretion].

A follicular thyroid carcinoma was suspected in a 62-year-old woman after the fifth goitre excision for non-neoplastic inappropriate thyrotropin secretion. Small-follicular adenoma could not be excluded histologically. After an attempt at thyrotropin suppression with L-thyroxine, triiodothyronine, D-thyroxine with L-thyroxine, and bromocriptine had failed, lasting if partial decrease in the maximally elevated TSH levels was achieved with triiodothyroacetic acid (TRIAC). One of the patient's three daughters also has non-neoplastic inappropriate thyrotropin secretion and has had two goitre excisions. It is most likely a familial form of inappropriate TSH secretion.

Carcinoma↗
PubMed1990

X-ray diffraction studies on plasma-sprayed calcium phosphate-coated implants.

Calcium phosphate coatings on steel, obtained by the plasma-spray technique, were examined by x-ray diffraction in order to get some information on their crystallographic structure and crystallinity. Surface roughness values were also determined. These coatings are of interest for hip-prosthesis materials in particular.

Biocompatible Materials↗
PubMed1990

Comparison between transport and degradation of leucine and glutamine by peripheral human lymphocytes exposed to concanavalin A.

Transport and pathways of leucine and glutamine degradation were evaluated in resting human peripheral lymphocytes and compared with the changes induced by concanavalin A (ConA). Cells were incubated with [1-14C]leucine (0.15 mM), [U-14C]leucine (0.15 mM), or [U-14C]glutamine (0.4 mM) after culture with or without 2, 5, 7, or 10 micrograms/ml ConA for 2, 18, or 24 hours, respectively. Initial rates of transport of leucine and glutamine were augmented 2.7-fold and threefold by the mitogen. Leucine transamination, irreversible oxidation, and catabolism beyond isovaleryl-CoA were increased by 90%, 20%, and 60%, respectively. Glutamine utilization increased threefold; accumulation of glutamate, aspartate, and ammonia increased by 700%, 50%, and 100%, respectively, and 14CO2 production by about 400% in response to ConA. The results indicate that ConA stimulates to about the same extent transport of leucine and glutamine into lymphocytes. Glutamine is mainly channeled into catabolic pathways, while leucine remains largely preserved. It is suggested that these metabolic changes provide more leucine for incorporation into protein and more N- and C-atoms required for the synthesis of macromolecules and energy from glutamine.

Ammonia↗
PubMed1990

Endosonography of pararectal lymph nodes. In vitro and in vivo evaluation.

One hundred thirteen patients with carcinoma of the rectum were evaluated for lymph node metastases by endorectal ultrasound. With the use of 7.5 MHz and based on different echo patterns, two main groups of lymph nodes can be differentiated: hypoechoic and hyperechoic lymph nodes. Compared with pathologic findings, hypoechoic lymph nodes represent metastases, whereas hyperechoic lymph nodes are visualized due to unspecific inflammation. Lymph node metastases can be predicted with a sensitivity of 72 percent and inflammatory lymph nodes with a specificity of 83 percent. The physical basis of the differentiation of lymph nodes was assessed in vitro by the determination of ultrasound parameters (speed of sound, acoustic impedance, attenuation, and backscattered amplitude). The attenuation coefficient of benign lymph nodes [2.5 dB/(MHz x cm)] is significantly higher than the mean value of lymph node metastases [1.3 db/(MHz x cm)]. The results demonstrate that involved nodes can principally be differentiated from not involved nodes. Micrometastases, mixed lymph nodes, and changing echo patterns within inflammatory nodes explain the accuracy rate of 78 percent.

Acoustics↗
PubMed1990

Diverse etiologies of facial paralysis in children.

Facial paralysis (FP) in children is most often idiopathic, however, many diverse and identifiable etiologies exist. Twenty-five cases of children admitted consecutively to the Children's National Medical Center over 8.5 years for the evaluation of FP were reviewed retrospectively. In 21 (84%) of the patients the FP was discovered to be secondary to a specific etiology or associated with a recognizable syndrome. In 7 cases, the FP was an initial manifestation of a serious underlying disorder. Causes of the FP in this series include: otitis media, mastoiditis, temporal lobe abscess, osteopetrosis, both blunt and penetrating trauma, iatrogenic surgical injury, facial burns, cerebellar astrocytoma, leukemia rhabdomyosarcoma, intracerebral arteriovenous malformation, Goldenhar syndrome, and Melkersson-Rosenthal syndrome. Four (16%) patients were diagnosed as having Bell's palsy. Methods of management, including the use of electrodiagnostic testing are described.

Adolescent↗
PubMed1990

Prochloraz as potent inhibitor of benzo[a]pyrene metabolism and mutagenic activity in rat liver fractions.

We have determined how prochloraz, an imidazole antifungal agent, affects the metabolism of benzo[a]-pyrene by hepatic microsomes from 3-methylcholanthrene treated male rats. The prochloraz-like 7,8-benzoflavone was a potent inhibitor of total benzo[a]pyrene metabolism while miconazole was a weak inhibitor. The proportion of benzo[a]pyrene dihydrodiols formed was decreased whereas phenols were increased by the in vitro addition of prochloraz. Furthermore, a good correlation was obtained between the effects of prochloraz on the microsomal formation of benzo[a]pyrene metabolites and on the mutagenic activity of benzo[a]pyrene in the Salmonella typhimurium test.

Animals↗
PubMed1990

Cellular immunologic parameters in HIV-positive patients with AIDS-related complex and intravenous immunoglobulin therapy.

In a randomized double-blind longitudinal study with 30 HIV-1-positive patients with AIDS-related complex or stage Walter-Reed 5 disease, the effectiveness of intravenous immunoglobulin (IVIG) was tested for correcting eventual immune dysregulation. Although the IVIG-treated patients showed an improvement of their clinical score, no significant changes were observed in lymphocyte phenotypes, activation markers, immunoglobulins and subclasses, lymphocyte turnover or in indicators of acute inflammation. Since severe bacterial infections or autoimmune processes usually leading to IVIG therapy were not prevalent in the patients of the study, such therapy should probably be reserved for later stages of the disease. HIV-1 antigen expression in blood lymphocytes remained uninfluenced by IVIG treatment.

AIDS-Related Complex↗
PubMed1990

The vasopressin receptor system in the neonatal pituitary gland: evidence for reduced binding capacity and signal transmission.

The present study was aimed at evaluating the capacity of anterior pituitary cells from neonatal rats to bind arginine vasopressin (AVP) and show AVP-receptor-mediated signal transmission. We found that in cultures of pituitary cells of 10-day-old pups, in contrast to cultures of cells of adults, AVP was unable to trigger sustained adrenocorticotropin (ACTH) secretion and, in addition, was also less potent in synergizing with the effect of corticotropin-releasing factor (CRF) on both ACTH output and cyclic AMP formation. Binding studies revealed the existence of a much lower number of AVP receptor sites in membranes of neonatal pituitary gland than in those of adult tissue (32.3 +/- 9.0 and 137.6 +/- 6.2 fmol/mg protein, respectively), although the binding of agonists and the apparent molecular weight (Mr about 120,000) of the receptors were similar. Activation by phorbol ester PMA of protein kinase C, a messenger involved in AVP action, resulted in a dose-related enhancement of ACTH secretion that was 2-3 times smaller for immature corticotrophs than for mature ones. Importantly, PMA treatment allowed AVP to significantly stimulate ACTH secretion from neonatal cells, while it failed to similarly affect AVP-evoked hormone output from adult tissue. Our results indicate that pituitary corticotrophs of rat pups fail to properly transduce AVP-receptor-mediated signalling and, thereby, suggest an explanation for the postnatal 'stress nonresponsive period'.

Adrenocorticotropic Hormone↗
PubMed1990

T-lymphocyte subsets in the duodenal lamina propria of patients infected with the human immunodeficiency virus type 1 and influence of high-dose immunoglobulin therapy.

T-lymphocyte subsets in duodenal biopsies of human immunodeficiency virus type 1 (HIV-1)-infected patients were studied by immunocytochemical staining to determine the alterations of CD4- and CD8-cell subsets in comparison with HIV-1 antibody-negative controls and to examine the association with stage, gastrointestinal symptoms, and peripheral lymphocyte subsets and the influence of high-dose intravenous immunoglobulins. A significant decrease in duodenal CD4 cells (p less than 0.001) and CD4/CD8 ratio (p less than 0.001) follows HIV-1 infection when compared to HIV-1-negative controls, more accentuated both in patients of stage WR6 and suffering from diarrhea than in those of stages WR1-5 or without diarrhea. In addition, a significant increase in CD8 cells (p less than 0.01) could be found in HIV-1-infected patients, again with lower levels in patients of stages WR6 than WR1-5. A strong correlation was found between the intestinal and peripheral CD4/CD8 ratio (R = 0.80), but the correlation was weak if HIV-1-negative persons were excluded from analysis (R = 0.29). Treatment with high-dose intravenous immunoglobulins improved diarrhea in four of five patients; two patients gained weight. Diffuse lymphocytic infiltration of the lamina propria, villous atrophy, CD4- and CD8-cell percentage, and CD4/CD8 ratio were not influenced.

Adult↗