Biomedical subjects
Publications and source records attributed to M Berg.
Wilson's disease is an inherited disorder which affects the body's ability to metabolize copper. The resulting copper toxicosis can involve all body organs but especially the liver, brain, cornea and kidneys. This article presents a review of the disease and a case study demonstrating how the disease changed a young woman's life, presenting many challenges to her, her family, her nurses and other care providers.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The mechanisms by which glyburide and tolbutamide signal insulin secretion were examined using a beta cell line (Hamster insulin-secreting tumor (HIT) cells). Insulin secretion was measured in static incubations, free cytosolic Ca2+ concentration ([Ca2+]i) was monitored in quin 2-loaded cells, and cAMP quantitated by radioimmunoassay. Insulin secretory dose-response curves utilizing static incubations fit a single binding site model and established that glyburide (ED50 = 112 +/- 18 nM) is a more potent secretagogue than tolbutamide (ED50 = 15 +/- 3 microM). Basal HIT cell [Ca2+]i was 76 +/- 7 nM (mean +/- S.E., n = 141) and increased in a dose-dependent manner with both glyburide and tolbutamide with ED50 values of 525 +/- 75 nM and 67 +/- 9 microM, respectively. The less active tolbutamide metabolite, carboxytolbutamide, had no effect on [Ca2+]i or insulin secretion. Chelation of extracellular Ca2+ with 4 mM EGTA completely inhibited the sulfonylurea-induced changes in [Ca2+]i and insulin release and established that the rise in [Ca2+]i came from an extracellular Ca2+ pool. The Ca2+ channel blocker, verapamil, inhibited glyburide- or tolbutamide-stimulated insulin release and the rise in [Ca2+]i at similar concentrations with IC50 values of 3 and 2.5 microM, respectively. At all concentrations tested, the sulfonylureas did not alter HIT cell cAMP content. These findings provide direct experimental evidence that glyburide and tolbutamide allow extracellular Ca2+ to enter the beta cell through verapamil-sensitive, voltage-dependent Ca2+ channels, causing a rise in [Ca2+]i which is the second messenger that stimulates insulin release.
Pharmacokinetic analysis of isoprene inhaled by male Wistar rats and male B6C3F1 mice showed saturation kinetics in both species. Below atmospheric concentrations of 300 ppm in rats and in mice the rate of metabolism is directly proportional to the concentration. The low accumulation of isoprene in the body at low atmospheric concentrations suggests transport limitation of the metabolism. Only small amounts of isoprene taken up are exhaled as unchanged substance (15% in rats and 25% in mice). Its half life in rats is 6.8 min and in mice 4.4 min. At concentrations above 300 ppm the rate of metabolism does not increase further in proportion to the atmospheric concentration. It finally approaches maximal values of 130 mumol/(h X kg) body weight at atmospheric concentrations above 1500 ppm in rats, and 400 mumol/(h X kg) body weight at concentrations above 2000 ppm in mice. This indicates limited production of the two possible mono-epoxides of isoprene at high concentrations. Isoprene is endogenously produced and is systemically available. Its production rate is 1.9 mumol/(h X kg) in rats, and 0.4 mumol/(h X kg) in mice, respectively. Part of the endogenous isoprene is exhaled by the animals but it is metabolized to a greater extent: the rate of metabolism of endogenously produced and systemically available isoprene is 1.6 mumol/(h X kg) (rats) and 0.3 mumol/(h X kg) (mice).
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A 2-year-old boy was found to have a 47,XXX karyotype. Restriction-fragment-length-polymorphism analysis showed that, of his three X chromosomes, one is of paternal and two are of maternal origin. The results of Y-DNA hybridization were reminiscent of those in XX males in two respects. First, hybridization to Southern transfers revealed the presence in this XXX male of sequences derived from the Y-chromosomal short arm. Second, in situ hybridization showed that this Y DNA was located on the tip of the X-chromosomal short arm. We conclude that this XXX male resulted from the coincidence of X-X nondisjunction during maternal meiosis and aberrant X-Y interchange either during or prior to paternal meiosis.
Noncompliance is a major problem that patient education aims at resolving. The emphasis in patient education upon didactic strategies, educational content, and materials distracts from perhaps the most important factor in the success of patient education, that is, the quality of the physician-patient relationship. In the context of the physician-patient relationship many of the patient's psychological needs, wishes, and fears will be revealed, and these factors have bearing upon compliance and the ability to make use of patient education. When the physician develops a psychotherapeutic attitude characterized by empathic attunement to the patient and his or her underlying psychological reasons for resistance to medical advice, the likelihood of accepting patient education increases.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The efficacy of the anti-herpesvirus drug buciclovir [(R)-9-(3,4-dihydroxybutyl)guanine] was investigated in guinea pigs and mice infected intravaginally with herpes simplex virus type 2. Topical treatment initiated early after infection was efficacious, in contrast to topical treatment delayed 24 h or more. Systemic treatment of infected mice could not prevent the spread of virus to the brain and mortality. Systemically administered buciclovir had an effect in guinea pigs, even after delayed onset of treatment, but this effect required high doses of the drug. Our results suggest that buciclovir has only a limited effect against herpesvirus infections once the virus is present in the nervous systems of infected animals.
Using a glucose-responsive beta cell line, we tested the hypothesis that the free cytosolic Ca2+ concentration ([Ca2+]i) is the primary signal that couples a stimulus to insulin secretion, and examined the involvement of the extracellular Ca2+ pool in this process. Glucose or depolarization of the beta cell with 40 mM K+ stimulated a monophasic release of insulin directly proportional to the extracellular Ca2+ concentration. 40 mM K+ increased 45Ca2+ uptake and increased [Ca2+]i, which was measured with quin 2, 4.7-fold, from 56 +/- 3 to 238 +/- 17 nM. With high glucose, 45Ca2+ uptake did not increase, and [Ca2+]i was unchanged or fell slightly. There was a striking correlation between inhibitory effects of verapamil, the Ca2+ channel blocker, on insulin secretion and the rise in [Ca2+]i evoked by K+. Higher concentrations of verapamil were required to inhibit glucose- than K+-stimulated insulin secretion (dose giving half-maximal effect of 1.4 X 10(-4) M vs. 6.0 X 10(-7) M). Incubation in Ca2+-free, 1 mM EGTA buffer for 30 min lowered [Ca2+]i to 14 +/- 2 nM, and inhibited acute insulin release to both secretagogues. If high glucose was present in the Ca2+-free period, reintroduction of 2.5 mM Ca2+ in high glucose restored insulin secretion only to the basal rate. However, if low glucose was present during the Ca2+-free period, high glucose and 2.5 mM Ca2+ triggered a full first-phase insulin response. These data suggest that high glucose generates a non-Ca2+ signal that turns over rapidly and provide direct evidence that K+ triggers insulin release by drawing extracellular Ca2+ into the beta cell through verapamil-sensitive Ca2+ channels. However, an increase [Ca2+]i is not the primary signal that evokes glucose-stimulated insulin release in this beta cell line.
The female copulatory behaviour (lordotic response) is inhibited by morphine. Female rats treated neonatally with naltrexone displayed enhanced copulatory behaviour as adults, and the morphine-induced lordosis inhibitory effect was diminished. The present data suggest that in the female rat the opioid mechanisms involved in the copulatory behaviour are established neonatally and can be influenced by early manipulation of the opioid system.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The enlarged transtemporal middle fossa approach to the cerebello-pontine angle is adequate for complete removal of acoustic neuromas up to 4.0 cm in diameter (sizes B and C according to Fisch). A description of the surgical technique and the results of 63 operations are presented (13, 23 and 27 tumours of sizes A, B and C respectively). 51 tumours were completely removed, 6 had a voluntary palliative incomplete resection for medical reasons or on the only remaining hearing ear. Only 6 patients (one in the last 40 consecutive cases) had an incomplete resection due to the limited exposure of the tumour. In 44 ears the cochlear nerve could be preserved, 28 of which showed postoperative hearing function (8 size A, 10 size B, 10 size C). There was no operative mortality, no severe hemorrhage nor any permanent neurological complication. The facial nerve function was well preserved in 48 of 56 patients followed up.