Biomedical subjects

S Maas

Publications and source records attributed to S Maas.

40 records · Page 3Linked to original sources

PubMed1988

Long-term omeprazole treatment in man: effects on gastric endocrine cell populations.

36 patients with chronic gastric or oesophageal peptic ulceration (including 6 with antrectomy), resistant to high-dose ranitidine treatment for at least 3 months, were successfully treated with 40-60 mg of omeprazole daily for periods between 1 and 2 years. Fasting serum gastrin levels were monitored at regular intervals during therapy and multiple gastric mucosal biopsies were taken during gastroscopy every 3-6 months. Gastrin levels increased significantly during the first 6 months of therapy from a medium level of 81.5 to 206 pg/ml, a slight decrease was seen thereafter. In 10 patients investigated before the start of the treatment and after 1 and 2 years, the volume density of argyrophilic cells in the oxyntic mucosa increased from 0.43 +/- 0.08 to 0.91 +/- 0.14% during the first year; this change was statistically significant. No further increase was observed thereafter. No such difference could be demonstrated between a larger group of 18 patients investigated before and after 1 year of treatment with omeprazole (0.806 +/- 0.1 vs. 0.93 +/- 0.08%) and between a larger group of 22 untreated patients and 17 patients treated for 17-24 months with omeprazole (0.73 +/- 0.1 vs. 0.86 +/- 0.09%). The volume density of argyrophilic cells found in 8 patients with gastrinoma amounted to 1.37 +/- 0.22%. No clusters of endocrine cells were found in omeprazole-treated patients. The D cell volume density in the antral mucosa decreased significantly during the first months of treatment, but steadily increased thereafter to reach pretreatment values after 17 months. There was no change in G cell volume density under therapy. No changes in gastrin levels or oxyntic argyrophilic cells were observed in the antrectomized patients. It is concluded that the hyperplasia of argyrophilic cells observed in some patients during long-term omeprazole treatment is mediated by hypergastrinaemia.

Female↗

PubMedDate not supplied

Surgical removal of subretinal neovascular membranes.

Since 1991 we have been gaining experience in the surgical removal of submacular subretinal membranes in patients with presumed ocular histoplasmosis syndrome (POHS), idiopathic subretinal neovascularisation, myopia and age-related macular degeneration (AMD). Seventeen patients were operated between 1991 and 1993. Significant improvement of vision was achieved in 4 out of 5 patients with POHS, 3 out of 5 with idiopathic neovascularisation, 2 out of 4 with myopia but none of 3 patients with AMD. The results suggest that subretinal neovascularisation can be successfully removed in POHS and in some forms of idiopathic neovascularisation and myopia but probably not in AMD.

Adult↗

PubMedDate not supplied

[Labor contraction-dependent changes in magnesium and calcium in the myometrium].

Magnesium is commonly used in the therapy and prevention of preterm labor. Therefore the differences of the concentrations of magnesium and its antagonist calcium were measured in the human myometrium to examine the interaction of labour and ionic changes. The ionic concentration in the myometrium of 37 patients without labour are determined and the values are compared to the data of 26 patients in active labour. Women of the first group without labour had a magnesium concentration of mean = 4.1 mmol/kg wet weight and a calcium concentration of mean = 2.9 mmol/kg wet weight. Women of the second group with active labour have a significantly lower (p < 0.01) magnesium concentration (mean = 3.5 mmol/kg wet weight). However, the calcium level (mean = 2.7 mmol/kg wet weight) does not show significant differences. These results indicate that the decrease of magnesium plays an important role in the physiology of parturition. A low magnesium concentration in the myometrium might have a considerable influence on premature labour in the third trimester of pregnancy. Therefore a prophylactic application of magnesium seems to be useful.

Adult↗

PubMedDate not supplied

Chromosomal changes and correspondingly altered proto-oncogene expression in human gliomas. Value of combined cytogenetic and molecular genetic analysis.

A combined cytogenetic and molecular genetic study was performed to analyze seven primary brain tumors: one oligoastrocytoma WHO-grade II, one anaplastic astrocytoma grade III, one anaplastic astrocytoma grade III/IV and four glioblastomas by G-banding and RNA dot blotting. A normal karyotype was found in the oligoastrocytoma. One of the two anaplastic astrocytomas (male) contained cells with a normal karyotype and cells with a Y-chromosomal loss, and the other one showed structural abnormalities too complex for complete analysis in mostly polyploid cells. Two of the four glioblastomas had few and the other two multiple chromosomal changes such as +7, +20, -8, -9 del(9)(p21), -10, del(10)(q24), -13,14, del(17)(p21), -22, add(3)(q13), double minutes and marker chromosomes. Compared to normal brain, all tumors had an increased EGFr and both anaplastic astrocytomas as well as three glioblastomas a decreased H-ras expression. The two glioblastomas with multiple chromosomal changes showed increased EGFr, Ki-ras, myb, mos and myc, decreased H-ras and N-ras and unchanged levels of abl, src and sis. Both the cytogenetic and molecular genetic findings are compatible even in the case of chromosomal losses, where the genes on the remaining allele may be responsible for dominant gene regulation mechanisms which result in a protooncogene overexpression. Our findings indicate that, apart from proto-oncogene overexpression, other mechanisms, e.g. tumor suppressor gene inactivation, are important for glial tumorigenesis. Karyotypic analysis makes it possible to search specifically for genetic events still unknown but arising from particular chromosomal changes.

Adult↗