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Biomedical subjects

L Holm

Publications and source records attributed to L Holm.

At least 145 records · Page 8Linked to original sources
PubMed1990

Effects of hypovolemia on blood flow, arterial [HCO3-], and HCO3- output in the rat duodenum.

The effects of bleeding-induced hypovolemia on duodenal blood flow (microsphere technique), arterial [HCO3-], and duodenal HCO3- secretion (in situ titration) were investigated in chloralose-anesthetized rats. A 10% decrease in blood volume reduced duodenal HCO3- secretion by 44%, duodenal blood flow by 31%, and arterial [HCO3-] by 11%. In a group with cervically cut vagal nerves, basal duodenal HCO3- secretion was greater than 50% lower compared with controls. Basal blood flow and arterial [HCO3-] were on similar levels as in nonvagotomized animals. Furthermore, bleeding failed to lower duodenal alkaline output in rats with cut vagal nerves, although blood flow and arterial [HCO3-] were reduced to a similar extent as in the vagally intact controls. In a yohimbine-treated group, a 10% bleeding reduced duodenal blood flow by 28% and arterial [HCO3-] by 7% without influencing duodenal HCO3- secretion. We suggest that the hypovolemia-induced inhibition of duodenal alkaline secretion is not caused by a decrease in blood and/or arterial [HCO3-]. Instead, other factors may be of importance, for example, neural effects on enteric secretomotor neurons or directly on the secreting epithelium.

Animals↗
PubMed1989

Primary structure of the brain alpha-spectrin.

We have determined the nucleotide sequence coding for the chicken brain alpha-spectrin. It is derived both from the cDNA and genomic sequences, comprises the entire coding frame, 5' and 3' untranslated sequences, and terminates in the poly(A)-tail. The deduced amino acid sequence was used to map the domain structure of the protein. The alpha-chain of brain spectrin contains 22 segments of which 20 correspond to the repeat of the human erythrocyte spectrin (Speicher, D. W., and V. T. Marchesi. 1984. Nature (Lond.). 311:177-180.), typically made of 106 residues. These homologous segments probably account for the flexible, rod-like structure of spectrin. Secondary structure prediction suggests predominantly alpha-helical structure for the entire chain. Parts of the primary structure are excluded from the repetitive pattern and they reside in the middle part of the sequence and in its COOH terminus. Search for homology in other proteins showed the presence of the following distinct structures in these nonrepetitive regions: (a) the COOH-terminal part of the molecule that shows homology with alpha-actinin, (b) two typical EF-hand (i.e., Ca2+-binding) structures in this region, (c) a sequence close to the EF-hand that fulfills the criteria for a calmodulin-binding site, and (d) a domain in the middle of the sequence that is homologous to a NH2-terminal segment of several src-tyrosine kinases and to a domain of phospholipase C. These regions are good candidates to carry some established as well as some yet unestablished functions of spectrin. Comparative analysis showed that alpha-spectrin is well conserved across the species boundaries from Xenopus to man, and that the human erythrocyte alpha-spectrin is divergent from the other spectrins.

Amino Acid Sequence↗
PubMed1988

Gastric mucosal blood flow and mucosal protection.

Prostaglandins (PGs) and omeprazole, both applied intraluminally, have been shown to induce mucosal protion, independently of their inhibitory effects on acid secretion. To investigate the influence of these groups of agents on the gastric mucosal microcirculation, quantitative intravital microscopy of the rat gastric mucosal microcirculation was performed. Single vessel blood flow, calculated from red blood cell velocity and diameter measurements, increased when PGE1, PGE2, 16,16-dimethyl-PGE2, or omeprazole were applied intraluminally. These results suggest that the increase in blood flow may, at least in part, be the reason for the protective action of these substances. A considerably reduced blood flow, such as occurs during hemorrhagic shock, is known to induce gastric bleeding, and also to induce neutrophil adherence to the endothelial wall. Neutrophil antiserum was used to determine whether neutropenia offered protection against hemorrhagic shock-induced gastric bleeding in anesthetized rats. Depletion of neutrophils resulted in higher blood flow during the ischemic period and also attenuated reperfusion-induced gastric damage. Maintenance of blood flow at the same level in untreated rats resulted in a similar reduction of mucosal damage. Thus, the major mechanism by which neutrophils appeared to increase damage in this model of gastric mucosal injury was by increasing microvascular resistance, thereby presumably intensifying tissue hypoxia. This paper is a summary review of previous studies.

16,16-Dimethylprostaglandin E2↗
PubMed1988

Role of blood flow in gastric acid secretion.

The relationship between gastric acid secretion and blood flow has been investigated with a variety of different blood flow techniques including aminopyrine clearance, hydrogen gas clearance, intravital microscopy, laser-Doppler flowmetry, radioactive microspheres, and the elimination of inert gases. The most commonly used technique, aminopyrine clearance, predicts that increasing acid secretion is accompanied by a parallel increase in blood flow. However, the efficiency of clearance of aminopyrine is low in the nonsecreting stomach and increases as secretion rate increases. This precludes the use of aminopyrine clearance as a reliable measure of gastric mucosal blood flow at all but the highest steady-state level of acid secretion and casts doubt on the findings with this technique. Other methods for measuring blood flow indicate that there is no simple relationship between secretion and flow, with some studies finding that secretion and flow change in parallel and others finding that secretion varies quite independently of flow to the mucosa. One consistent finding is a strong correlation between stimulated acid secretion and gastric oxygen consumption. Both acid secretion and oxygen consumption fall if celiac blood flow is reduced below a critical value, which in the anesthetized dog stomach is approximately 30-40 ml.min-1.100 g-1. Driving blood flow above this value does not increase oxygen consumption and acid secretion, i.e., they reach a plateau. The shape of this relationship with its flow-dependent and flow-independent portions is used to explain the apparently contradictory findings in the literature regarding gastric acid secretion and blood flow.

Aminopyrine↗
PubMed1988

Relationship of chronic pelvic pain to psychiatric diagnoses and childhood sexual abuse.

Structured psychiatric and sexual abuse interviews were administered to 25 women with chronic pelvic pain and a comparison group of 30 women with specific gynecological conditions. All 55 patients underwent diagnostic laparoscopy, and the results of the fiberoptic pelvic examination were objectively classified by the study gynecologist, who was blind to the psychiatric diagnoses. The patients with chronic pelvic pain showed a significantly higher prevalence of major depression, substance abuse, adult sexual dysfunction, somatization, and history of childhood and adult sexual abuse than the comparison group. There were no significant differences between the groups in severity or type of pelvic pathology.

Adolescent↗
PubMed1988

The association between chronic pelvic pain, psychiatric diagnoses, and childhood sexual abuse.

Twenty-five women with chronic pelvic pain who had undergone diagnostic laparoscopy and 30 women who had laparoscopic examinations for tubal sterilization or infertility investigation were compared psychologically using structured psychiatric and sexual abuse interviews. Results of the fiberoptic pelvic examination were rated independently using the American Fertility Society classification of endometriosis. Compared with controls, the patients with chronic pelvic pain showed significantly greater prevalence of lifetime major depression, current major depression, lifetime substance abuse, adult sexual dysfunction, and somatization. They were also significantly more likely than controls to have been a victim of childhood and adult sexual abuse. There were no significant differences in either the degree or type of pelvic disease between patients with pelvic pain and controls.

Child↗
PubMed1987

Structural models of the redox centres in cytochrome oxidase.

Evolutionary conservation, predicted membrane topography of the subunits, and known chemical and physical properties of the catalytic metals in cytochrome oxidase provided the basis for plausible structural models of the enzyme's redox centres. Subunit II probably binds one of the copper ions (CuA) whilst subunit I is likely to bind the two haems (a and a3) and the other redox-active copper (CuB). Two cysteine and two histidine residues of subunit II are the likely ligands of CuA, forming a centre that may be structurally similar to that in azurin. The two haems may be sandwiched between two transmembranous segments of subunit I, one of which also provides a histidine ligand to CuB. A third segment may provide two more histidine ligands to the latter. The model was constructed with a 4 A Fe-Cu distance in the binuclear haem a3-CuB centre, and a 14 A distance between the haem irons. The subunit I model involves only three transmembranous helices which bind three catalytic metal groups. The fit of this model to several known physicochemical properties of the redox centres is analysed.

Animals↗
PubMed1986

Codon usage and gene expression.

The hypothesis that codon usage regulates gene expression at the level of translation is tested. Codon usage of Escherichia coli and phage lambda is compared by correspondence analysis, and the basis of this hypothesis is examined by connecting codon and tRNA distributions to polypeptide elongation kinetics. Both approaches indicate that if codon usage was random tRNA limitation would only affect the rarest tRNA species. General discrimination against their cognate codons indicates that polypeptide elongation rates are maintained constant. Thus, differences in expression of E. coli genes are not a consequence of their variable codon usage. The preference of codons recognized by the most abundant tRNAs in E. coli genes encoding abundant proteins is explained by a constraint on the cost of proof-reading.

Bacteriophage lambda↗
PubMed1986

The clinical versus radiological diagnosis of alcoholic cerebellar degeneration.

We report the clinical characteristics of 65 patients with alcoholic cerebellar degeneration as verified by computerized tomography of the brain. Thirty-two patients (49%) had clear clinical signs of the disease such as broad-based staggering gait, impaired heel-to-toe walking, terminal oscillations in heel-knee test and slow (3/s) leg tremor. These signs were virtually absent in 33 patients (51%) who, nevertheless, had radiological signs of cerebellar degeneration. Traumatic brain injuries were more frequent in those patients who had both clinical and radiological signs of alcoholic cerebellar degeneration. Furthermore, this group showed longer periods of heavy drinking, more severe cerebral atrophy and more profound neuropsychological impairment than a control group of 92 alcoholics with neither clinical nor radiological signs of cerebellar disease. We conclude that careful clinical neurological examination is needed to diagnose alcoholic cerebellar degeneration which is apparently a more common disease than first realized. Subclinical cases can be diagnosed with the help of computerized tomography of the brain.

Adult↗
PubMed1986

Contribution of traumatic head injury to neuropsychological deficits in alcoholics.

The contribution of head injuries to neuropsychological deficits was studied in 157 recently detoxified alcoholics and 400 control subjects consisting of age-stratified randomly selected men and women from the same geographical area as the alcoholics. Head injuries had occurred in 41% and 22% of the male and female alcoholics, but only in 15% and 6% of the male and female control subjects. One third of the injured subjects in both groups had been admitted to hospital for treatment of the acute injury. The neuropsychological test results of alcoholics were significantly inferior to those of control subjects. Unexpectedly, alcoholics with head injuries not identified at hospital were significantly inferior in several Halstead-Reitan subtests when compared with uninjured alcoholics with a similar duration of alcoholism and abstinence. By contrast, control subjects who had sustained a head injury not identified at hospital did not show signs of intellectual impairment when compared with uninjured controls. We conclude that traumatic brain injuries that may cause significant intellectual impairment may easily remain unrecognised in alcoholics.

Adult↗
PubMed1984

Computed tomography and ultrasound studies of prostatic utricle cyst associated with unilateral renal agenesis. A case report.

A case history is presented regarding a prostatic utricle cyst associated with unilateral renal agenesis in a young man. The cause of this developmental defect is elucidated. The diagnostic findings using computed tomography and ultrasound examination in addition to intravenous pyelography are reported and the value of these new examinations is emphasized.

Adult↗