Role of myelin basic protein and proteolipid protein genes in multiple sclerosis: single strand conformation polymorphism analysis of the human sequences

Susceptibility to multiple sclerosis (MS) is widely held to have a strong genetic component. While the identities of genes conferring susceptibility are currently unknown, possible candidates include those genes coding for proteins which function in central nervous system (CNS) myelin. Two such genes are the human myelin basic protein (MBP) and proteolipid protein (PLP) genes, whose products make up approximately 80% of the total protein in CNS myelin. The association of a variable number tandem repeat (VNTR) 5' to the human MBP gene with MS has been the subject of conflicting reports. Here we test the hypothesis that mutations in the human MBP and PLP genes might be associated with MS by examining the entire expressed sequence of both genes by single strand conformation polymorphism (SSCP) analysis, using a panel of 71 MS patients and 71 controls. We have also re-examined the VNTR region in patients and controls. Three base changes were found in the human PLP gene and nine base changes in the human MBP gene; these were essentially equally distributed between patients and controls. No preferential distribution of various alleles of the VNTR between patients and controls was found. Although intronic and regulatory regions have not been examined, it would appear unlikely that mutations in these genes coding for the two major CNS myelin proteins contribute significantly to genetic susceptibility to MS.

Molecular remodeling of cardiac contractile function

A number of techniques are now available that allow the contractile apparatus of the heart to be altered in a defined manner. This review focuses on those approaches that result in germ-line transmission of the remodeling event(s). Thus the desired modifications can be propagated stably throughout multiple generations and result in the creation of stable, new animal models. Necessarily, such stable changes need to be performed at the level of the genome, and two distinct but complementary approaches have been developed: transgenesis and gene targeting. Each results in the stable modification of the mammalian genome. Via gene targeting or gene ablation of sequences encoding various components of the sarcomere, the contractile apparatus of the heart can be altered dramatically. Ablating a gene may lead to a loss in function, which can help establish a function of the candidate sequence. Gene targeting can also be used to effect changes in the sequences encoding a functional domain of the contractile protein or at a single-amino acid residue, resulting in the establishment of precise structure-function relationships. With the use of transgenesis, the contractile apparatus of the heart can also be significantly remodeled. These approaches are rapidly creating a group of animals in which altered contractile protein complements will lead to a fundamental understanding of the structure-function relationships that underlie the function of the heart at the molecular, biochemical, whole organ, and whole animal levels.

Correlation of clinical and hematologic profiles with bone marrow responses in typhoid fever

Thirty-six adult patients with typhoid fever were studied. Severe, moderate, and mild typhoid fevers were observed in 17 (47.2%), 17 (47.2%), and two (5.6%) patients, respectively. Twenty-eight (77.8%) had either isolated anemia (i.e., anemia unaccompanied by other blood component cytopenias) or mixed cytopenias. Three patients (8.3%) had pancytopenia. Sixteen patients (44.5%) had either total or partial bone marrow suppression. In five (31.3%) with partial suppression, the effect of bone marrow suppression was not reflected in peripheral blood. Sixteen (48.5%) of 33 had peripheral blood cytopenias that were not accompanied by concurrent bone marrow suppression, suggesting a peripheral mechanism responsible for the blood dyscrasia in those cases. No patient had evidence of disseminated intravascular coagulopathy. There was no correlation between clinical severity of disease and bone marrow changes. Bone marrow/peripheral blood changes did not influence the outcome of the disease, since all the patients recovered fully after treatment.

Living on the edge--patients with an automatic internal cardioverter defibrillator (AICD): implications for nursing practice

Automatic internal cardioverter defibrillator (AICD) therapy is an expanding treatment option for patients experiencing sudden cardiac death events [Author: is this the correct term? It sounds as if they have in fact died. Could we say 'experiencing sudden, potentially fatal, cardiac events'?]. The paper outlines the background to the technique and the nursing care of such patients and their families. It recommends that future nursing research should focus on exploring the impact, on the patients and their families, of living with this device.

Distinct compartmentalization of TGN46 and beta 1,4-galactosyltransferase in HeLa cells

The Golgi proteins, TGN46 and GalT, were characterized in human HeLa cells using specific polyclonal and monoclonal antibodies. A bacterially expressed soluble recombinant TGN46 protein was used to raise rabbit polyclonal antibodies and used to probe HeLa cell extracts. Human TGN46 had an apparent molecular mass of 100 to 120 kDa which reflects extensive glycosylation. Epifluorescence light microscopy indicated substantial colocalization of TGN46 and GalT. However, confocal laser microscopy and three-dimensional reconstruction of double-labeled HeLa cells revealed large areas of colocalization but also specific differences in the distribution of these two proteins within the Golgi apparatus. Importantly, quantitative immunoelectron microscopy showed that there was little overlap between the distribution of GalT and TGN46. Approximately 75% of GalT was in the Golgi stack, whereas 80% of TGN46 was detected in tubules. Distinct GalT-positive regions within the Golgi cisternal stack were not labeled for TGN46.

Collagen content in rat liver after experimentally induced cholestasis followed by choledochojejunostomy and X-irradiation

The right part of the median lobe of the liver of female Wistar rats was irradiated, 12.5 or 25 Gy, at a field size of 15 x 20 mm. The central part of the irradiated liver lobe was fixed and used for the estimation of the collagen protein ratio by means of the Sirius Red-Fast Green extraction method, immediately, 8, 16 or 32 weeks after irradiation. No significant increase in collagen content could be demonstrated in this time range, both after irradiation at 12.5 Gy and at 25 Gy. Partial hepatectomy according to Higgins led to rapid regrowth of the remaining liver lobes. The right lobe grew out rapidly to replace the median lobe. Two days after partial hepatectomy the right lobe was irradiated at the same field size. Measurement of the collagen protein ratio in this experiment did not show a significant increase 8, 16 or 32 weeks after irradiation. However, the 25 Gy group did not survive long enough to obtain data at 16 or 32 weeks. The animals in this latter experiment suffered from ascites before dying. Experimentally induced cholestasis was obtained by ligation and partial resection of the common bile duct. After two weeks of cholestasis the bile flow was restored by Roux-en-Y choledochojejunostomy. The effect of irradiation 2 days after repair surgery was studied. Without irradiation the collagen protein ratio is increased. Irradiation of the right part of the median lobe led to a relatively enhanced collagen content in this lobe. Our results indicate that radiation itself does not lead to a significantly enhanced degree of fibrosis in the liver. However when an increase in collagen content was induced by cholestasis, the partial "dilution" of enhanced fibrosis as a result of proliferation of liver parenchyma cells following repair surgery was inhibited by irradiation.

Application of enzymes in food processing

Enzymes offer potential for many exciting applications for the improvement of foods. There is still, however, a long way to go in realizing this potential. Economic factors such as achievement of optimum yields and efficient recovery of desired protein are the main deterrents in the use of enzymes. Changing values in society with respect to recombinant DNA and protein engineering technologies and the growing need to explore all alternative food sources may in time make enzyme applications more attractive to the food industry. Research is continuing on the commercially viable enzymes in use today to improve various properties such as thermostabilities, specificities, and catalytic efficiencies. New and unique enzymes continue to be developed for use in enzymatic reactions to produce food ingredients by hydrolysis, synthesis, or biocatalysis. An aggressive approach is needed to open new opportunities for enzyme applications that can benefit the food industry.

Results of an office-based training program in clinical breast examination for primary care physicians

BACKGROUND

This study hypothesized that an office-based training program in clinical breast examination (CBE) would improve the lump-detection skills of primary care physicians.

METHODS

A one-group pretest-posttest design was utilized, without outcome measurements taken prior to instruction, immediately afterwards, and six months later. Fifty physicians from 117 practices that had been randomly selected and met program eligibility criteria elected to participate. The intervention was a one-hour office-based CBE training program based on the MammaCare method, a standardized approach to teaching the detection of breast lumps using silicone breast models.

RESULTS

There were five lumps in the silicone model. The mean number of correct lump detections increased significantly, from 0.66 before to 3.2 after instruction, and this gain was maintained at six-month follow-up. The mean number of false positives decreased from 2.9 before to 1.16 after instruction, increasing slightly to 1.6 at six-month follow-up. Ninety-six percent of the physicians reported that they had modified their methods of CBE as a result of the training.

CONCLUSIONS

This office-based instruction using an academic detailing model improved the participating physicians' abilities to correctly detect lumps in a silicone breast model and was received favorably.

Management of the hot thyroid nodule

BACKGROUND

Solitary hyperfunctioning nodules of the thyroid gland are usually viewed as benign. They may present with autonomous euthyroidism but are of concern for potential progression to hyperthyroidism. Various methods of treatment are worthy of consideration.

PATIENTS AND METHODS

Forty-five patients with solitary hot thyroid nodules verified by radioisotope scintiscanning were selected for treatment. Thirty-one underwent surgery, usually partial thyroidectomy. Eight euthyroid patients received no treatment, 5 underwent therapy with radioactive iodine (RAI), and 1 received thyroid suppression treatment. The cases were assessed retrospectively.

RESULTS

Thyroidectomy patients had no morbidity, were well, and showed 1 Hürthle cell tumor and 5 coincidental small malignancies associated with benign hot nodules, including a contralateral cancer. Untreated patients showed continuance of good health, but nodules persisted and 1 Graves' orbititis occurred. The RAI-treated patients had persistent nodularity, improved function, and 1 case of hyperparathyroidism. Thyroid feeding only caused iatrogenic toxicity and was discontinued.

CONCLUSIONS

There are various techniques for managing the hot nodule. Nonsurgical methods may be effective, but can result in persistent nodularity and iatrogenic sequelae. Excision had no morbidity in this series and was effective in providing immediate relief of problems present and potential.

The GLUT5 hexose transporter is also localized to the basolateral membrane of the human jejunum

The intestine is a major site of expression of the human GLUT5 hexose transporter, which is thought to be localized exclusively to the brush border membrane (BBM) where its major role is likely to be in the absorption of fructose. In this study we present novel biochemical and morphological evidence showing that the GLUT5 transporter is also expressed in the basolateral membrane (BLM) of the human intestine. BBM and BLM were isolated by fractionation of human jejunum. BBM were enriched with alkaline phosphatase activity by over 9-fold relative to a crude jejunal homogenate and contained immunoreactive sucrase-isomaltase and GLUT5 proteins. By contrast the BBM fraction was substantially depleted of immunoreactive a1 subunits of the Na,K-ATPase and GLUT2 glucose transporters which were abundantly present in the BLM fraction. This BLM fraction was enriched by over 11-fold in potassium-stimulated phosphatase activity relative to the crude homogenate; BLM also reacted to immunological probes for GLUT5 but showed no observable reactivity with antibodies directed against sucrase-isomaltase. Quantitative immunoblotting revealed that the BBM and BLM contained near equal amounts of GLUT5 per mg of membrane protein. Immunogold localization of GLUT5 on ultrathin sections of human jejunum showed that GLUT5 was present in both apical BBM and BLM. This gold labelling was absent when antiserum was pre-incubated with the antigenic peptide corresponding to a specific C-terminal sequence of human GLUT5. Quantitative analyses of the number of gold particles per unit length of BBM and BLM indicated that the mean density of gold labelling was marginally greater in the BBM (0.399 gold particles/micrometer) than in the BLM (0.293 gold particle/micrometer). The localization of GLUT5 in the BLM of the human jejunum may suggest that it specifically participates in the transfer of fructose across the basal membrane of the enterocyte.

Adaptive sex-dependent changes in the zonation of carbohydrate and lipid metabolism in rat liver lobules after partial hepatectomy

To evaluate changes in metabolic heterogeneity in rat liver lobules after partial hepatectomy, we measured parameters of carbohydrate and lipid metabolism cytophotometrically in periportal and pericentral zones of livers of mature female and male rats. Glycogen content was shown to be always higher in pericentral zones than in periportal zones. After a rapid depletion of glycogen stores during the first 8 hr after partial hepatectomy, the levels were restored to normal after 24 hr, but a significant depletion was found again at 48 hr after operation. These fluctuations were similar in female and male rat livers. The lipid content in control rat livers was low and was mainly localized in periportal zones. Partial hepatectomy caused a significant increase in lipid content after 24 to 48 hr in periportal zones only, which was distinctly higher in female than in male rat livers. Activity of NADPH-producing glucose-6-phosphate dehydrogenase was heterogeneously distributed in lobules of female control rats with highest activity in pericentral zones, whereas a lower but evenly distributed activity was found in lobules of control male rats. The activity was not affected by partial hepatectomy in male rats, whereas the activity in female rat livers decreased to levels found in male rats at 24 to 48 hr after operation. Another NADPH-producing enzyme, malate dehydrogenase, showed the highest activity pericentrally in female rats, and a low activity was evenly distributed in male rats. The activity did not change significantly after partial hepatectomy. The ketogenic enzyme beta-hydroxybutyrate dehydrogenase showed the highest activity in pericentral zones of control livers. The activity in male rat livers was almost twice as high as in female rat livers in both zones. Partial hepatectomy caused a distinct reduction in activity in both zones and both sexes, but the strongest reduction was found periportally. Alkaline phosphatase activity, which is linked with bile acid secretion by hepatocytes, was low in control male and female rats and was mainly found periportally. The activity was increased dramatically at 24 to 48 hr after partial hepatectomy in both zones and particularly in male rat livers. The index for the Krebs cycle, succinate dehydrogenase activity, was highest in periportal zones. At 24 to 48 hr after partial hepatectomy, this preferential zonation was lost, and the activity was slightly higher in pericentral zones. This reversal of zonation was found in all livers of female and male rats investigated.(ABSTRACT TRUNCATED AT 400 WORDS)