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Biomedical subjects

R J Grand

Publications and source records attributed to R J Grand.

At least 19 recordsLinked to original sources
PubMed1992

Messenger RNA sorting in enterocytes. Co-localization with encoded proteins.

This study describes the intracellular compartmentalization of three different mRNAs in the polarized rat fetal enterocyte. They encode proteins that are known to be localized within different regions of the epithelial cell namely (i) the apical, membrane-bound glycoprotein, lactase-phlorizin hydrolase (lactase), (ii) the mitochondrially localized enzyme, carbamoylphosphate synthetase (CPS), and (iii) the cytoplasmically localized enzyme, phosphoenolpyruvate carboxykinase (PEPCK). These mRNAs are found in close proximity to their respective protein products, i.e. the apical membrane, mitochondria and cytoplasm, respectively. The significance of these observations is twofold; (i) they indicate that mRNAs are sorted into specific domains of the cytosol of intestinal epithelial cells; and (ii) they imply the presence of two distinct pathways of mRNA targeting one that allows transport of mRNAs that are translated on ribosomes associated with the rough endoplasmic reticulum (lactase mRNA), and the other that allows sorting of mRNAs that are translated on free polysomes (CPS and PEPCK mRNA).

Animals↗
PubMed1992

Vitronectin is the major serum protein essential for NGF-mediated neurite outgrowth from PC12 cells.

The rat pheochromocytoma cell line PC12 can be induced to differentiate in response to nerve growth factor (NGF) in the presence of 1% fetal calf serum (FCS). Using a novel assay procedure we have developed a purification protocol which has allowed the isolation of the protein in serum responsible for neurite outgrowth after NGF treatment. FCS has been fractionated using four chromatographic procedures and in each case the peak of biological activity copurified with vitronectin. We have concluded, therefore, that vitronectin is the protein present in FCS which can mediate NGF-dependent neurite outgrowth in PC12 cells. Vitronectin and fibronectin from FCS have been chromatographically separated and only the former is capable of inducing neurite outgrowth. We have also shown that vitronectin utilizes the RGD amino acid sequence in binding to the surface of PC12s.

Amino Acid Sequence↗
PubMed1992

Vitamin E deficiency and impaired cellular immunity related to intestinal fat malabsorption.

This report describes a patient in whom a severe vitamin E deficiency developed secondary to an intestinal malabsorptive disorder. In vivo and in vitro impairment of T-cell function, as well as a polyneuropathy, were observed in conjunction with this vitamin deficiency. Repletion of the vitamin deficiency was associated with marked improvement in the T-cell functions and modest improvement in the neuropathy. Observations in this patient suggest that severe vitamin E deficiency in humans may impair T-cell activity and that correction of the deficient state may reverse these T-cell abnormalities. Further studies will need to be performed to confirm these findings.

Fats↗
PubMed1992

Lactase gene expression during early development of rat small intestine.

Expression of lactase messenger (m) RNA and protein in rat small intestine during fetal and postnatal development was analyzed using in situ hybridization and immunohistochemistry. Lactase mRNA was first identified at 18 days of development, and lactase protein was first detected at day 20. Lactase mRNA and protein were present along the entire villus. Lactase mRNA increased, reaching a maximum at day 20. Just before birth a decrease in lactase mRNA was observed. In newborn intestine, lactase mRNA was present only from the base of the villus up to the mid-villus region and was undetectable up to the villus tips. Lactase protein continued to be expressed along the entire villus. These data show that expression of lactase mRNA and protein do not parallel, indicating a posttranscriptional control in fetal development. Lactase gene transcription is initiated late in gestation concomitant with villus formation and is exclusively seen in villus epithelial cells. The restriction after birth of lactase mRNA expression to cells at the villus base suggests the occurrence of a previously unknown step in postnatal differentiation of the enterocyte.

Age Factors↗
PubMed1992

Efficacy of cimetidine for gastric acid suppression in pediatric patients.

The efficacy of oral cimetidine for gastric acid suppression in pediatric patients was examined in a double-blind study. Twenty-seven patients with gastroesophageal reflux-related gastrointestinal symptoms, pulmonary symptoms, or both were given randomly determined doses of cimetidine. Response was evaluated by continuous intragastric monitoring with a pH probe. Twenty-three patients were given cimetidine doses of 5,7.5, and 10 mg/kg; eight of these patients were also given additional doses of 15 mg/kg. Four patients received only 10 and 15 mg/kg, because of previous poor clinical response to the lower dosages. The onset of gastric pH greater than 4 was delayed more than 2 hours in 50% of patients with responses to the 5 mg/kg dose. Of the patients with responses to the 10 mg/kg dose, 75% had showed a rise in gastric pH greater than 4 within 2 hours. With respect to the duration of gastric acid suppression, 70% of patients receiving 5 mg/kg doses and 52% of those receiving 7.5 mg/kg doses did not have a sustained a response for more than 2 hours, whereas 75% of patients receiving 10 mg/kg doses had gastric acid suppression for longer than 2 hours. Of the patients receiving 15 mg/kg doses, 75% had a response for more than 2 hours; 50% of these patients had a response for more than 3 hours. We conclude that recommended doses of cimetidine for children may not be optimal for adequate gastric acid suppression.

Administration, Oral↗
PubMed1992

Molecular basis of lactase levels in adult humans.

The molecular basis of adult human "lactase deficiency" has long been a subject of controversy. To address this issue, small intestinal biopsies from orienta, black, and white patients were analyzed. Adjacent samples were assayed for lactase and sucrase specific activities and the sucrase/lactase ratio (high ratio signifies lactase deficiency), and the results were compared to lactase steady-state mRNA levels detected in Northern blots probed with a human lactase mDNA. All oriental patients had high ratios and no detectable lactase mRNA. Four black patients had a similar pattern; two with low ratios had detectable mRNA. The group of white patients displayed a range of findings, from high ratio/no mRNA to low ratio/considerable mRNA. Elevated levels of lactase mRNA always correlated with the presence of elevated levels of lactase enzyme activity, suggesting that the difference in levels of adult human intestinal lactase activity among racial groups may be regulated at the level of gene transcription.

Adult↗
PubMed1992

Cellular localization and T antigen binding of the retinoblastoma protein.

Mutation of the retinoblastoma (Rb) gene is found frequently in human sarcomas, lung, bladder and breast carcinomas and is the molecular basis for hereditary predisposition to retinoblastoma. The Rb protein is a nuclear phosphoprotein that is differentially phosphorylated during the cell cycle. Its precise function is unknown but it has been suggested that it may act as a transcriptional regulator or as a regulator of cellular DNA synthesis. The Rb protein forms specific complexes with the oncogenes of three different groups of DNA tumour viruses. We have prepared a new monoclonal antibody to the Rb protein and used it to establish sensitive immunoassays for Rb complexed to T antigen. In SV40-infected and transformed cells these assays showed that Rb enters a trimolecular complex containing p53, Rb and T. A large panel of human tumour cell lines was tested for expression, cellular localization and T-binding activity of Rb using the new antibody.

Antibodies, Monoclonal↗
PubMed1991

Cortisone and thyroxine modulate intestinal lactase and sucrase mRNA levels and activities in the suckling rat.

Glucocorticoids and thyroxine modulate postnatal intestinal sucrase and lactase activities. Whether changes in enzyme activity are accompanied by changes in enzyme mRNA levels were determined in day 6 rats given thyroxine, cortisone, or thyroxine plus cortisone and killed 3 days later. Cortisone induced precocious expression of jejunal sucrase activity which was enhanced when cortisone plus thyroxine was administered; sucrase mRNA changed in parallel. Jejunal lactase activity was unaffected by thyroxine and was increased after cortisone, but not after thyroxine plus cortisone. Jejunal lactase mRNA levels increased equally after cortisone or after cortisone plus thyroxine. Thus, cortisone induces coordinated increases in sucrase and lactase activities and in corresponding mRNA levels. Thyroxine only enhances cortisone induced sucrase expression and antagonizes cortisone by depressing lactase activity post-translationally.

Animals↗
PubMed1991

The use of beta-galactosidase fusion proteins encoding the early region 1 transforming proteins of adenovirus type 12 to examine the humoral response in tumour-bearing animals.

Sera from 26 rats bearing tumours induced by wild-type (wt) and mutant human adenovirus type 12 (Ad12), or by cells transformed with these viruses, were analysed for antibodies against the early region 1 (E1) transforming proteins. Six Ad12-beta-galactosidase fusion proteins encoding different regions of the Ad12 E1 proteins were constructed. The sera from the tumour-bearing animals reacted most strongly with the fusion protein encoding the N terminus of the E1A protein. Tumour-bearing rats exposed to the E1B 54K and 19K proteins showed strong reactions with the N terminus of the 54K protein and the C terminus of the 19K protein. Monospecific polyclonal antisera were raised against five of the fusion proteins by immunization of rats and rabbits; these sera cross-reacted with the purified native protein. No antibodies could be obtained which recognized a fusion protein containing amino acids 136 to 268 of the 54K protein. The fusion proteins were also used to purify monospecific antisera from tumour-bearer sera using affinity chromatography.

Adenoviridae Infections↗
PubMed1991

Induction of Epstein-Barr virus lytic cycle by tumor-promoting and non-tumor-promoting phorbol esters requires active protein kinase C.

Exposure to the tiglian 12-O-tetradecanoylphorbol-13-acetate (TPA) represents one of the most efficient and widely used protocols for inducing Epstein-Barr virus (EBV)-infected cells from latent into lytic cycle. Since TPA is both a potent tumor promoter and a potent activator of the cellular protein kinase C (PKC), we sought to determine whether either of these activities was closely linked to EBV lytic cycle induction. A panel of TPA structural analogs, encompassing tiglians with different spectra of biological activities, was assayed on a number of EBV-positive B-lymphoid cell lines. Lytic cycle induction correlated with the capacity to activate PKC, not with tumor promoter status; some nonpromoting tiglians were as efficient as TPA in inducing lytic cycle antigen expression. We then sought more direct evidence for an involvement of PKC in the induction process. In initial experiments, 1-(5-isoquinolinyl sulphonyl)-2-methylpiperazine (H-7), the best available pharmacological inhibitor of PKC, completely blocked the induction of the lytic cycle by TPA and its active analogs. This is consistent with, but does not prove, a requirement for active PKC in the induction process, since H-7 targets PKC preferentially but also has some effects on other kinases. We therefore turned to the synthetic pseudosubstrate peptide PKC(19-36) as a means of specific PKC inhibition and to the closely related but inactive peptide PKC(19-Ser-25-36) as a control. Using the technique of scrape loading to deliver the peptides into cells of an adherent EBV-positive target line, we found that the pseudosubstrate peptide PKC(19-36) completely and specifically blocked tiglian-induced entry of the cells into the lytic cycle. The evidence both from TPA analogs and from enzyme inhibition studies therefore indicates that the pathway linking TPA treatment to lytic cycle induction involves active PKC. Interestingly, inhibition of PKC had no effect upon the spontaneous entry into lytic cycle which occurs in naturally productive cell lines, suggesting that spontaneous entry is signalled by another route.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Clinical aspects of lactose intolerance in children and adults.

The principal carbohydrate of human milk is the disaccharide lactose. In human and all mammalian species, lactose is hydrolyzed in the small intestine by lactase-phlorizin hydrolase, also abbreviated as lactase. The absence of lactase results in the passage of undigested lactose into the large intestine and is associated with a well-known clinical syndrome: lactose intolerance. Low lactase levels result either from intestinal injury or, as in the majority of world's adult population, from alterations in the genetic expression of lactase. In this review terminology, pathophysiology, symptoms, diagnostic procedures, and therapy of lactose intolerance will be discussed.

Adult↗
PubMed1991

Development and validation of a pediatric Crohn's disease activity index.

Clinical and laboratory observations of 133 children and adolescents with Crohn's disease were used to validate an index of severity of illness previously developed by a group of senior pediatric gastroenterologists at a research forum in April 1990. This pediatric Crohn's disease activity index (PCDAI) included (a) subjective reporting of the degree of abdominal pain, stool pattern, and general well-being; (b) presence of extraintestinal manifestations, such as fever, arthritis, rash, and uveitis; (c) physical examination findings; (d) weight and height; and (e) hematocrit, erythrocyte sedimentation rate, and serum albumin. Independent evaluation of each patient by two physician-observers was performed at the time of a visit, and each physician completed a PCDAI index and a modified Harvey-Bradshaw index and made a "global assessment" of disease activity as none, mild, moderate, or severe. Excellent interobserver agreement was noted for the PCDAI, modified Harvey-Bradshaw index, and global assessment. There was a strong correlation between global assessment and both the PCDAI or modified Harvey-Bradshaw. Increasing PCDAI scores were noted with increasing disease severity, and significant differences in scores were noted between the severity groups. We propose that the PCDAI could be used in multicenter projects to facilitate patient stratification by disease severity and that longitudinal PCDAI scores might provide a numerical measure of response to therapeutic regimens.

Adolescent↗
PubMed1990

Coordinate expression of lactase-phlorizin hydrolase mRNA and enzyme levels in rat intestine during development.

The development of rat intestinal lactase-specific activity displays a well-known post-weaning decline. In contrast, total lactase activity increases to reach maximal levels around weaning, and remains high subsequently. In order to elucidate the molecular basis for these patterns, a rat lactase cDNA was isolated and characterized, and used in the quantification of lactase mRNA during development. This lactase cDNA uniquely hybridized to a 6.8-kilobase mRNA in the small intestine. To assess the amount of lactase mRNA encoding for lactase enzyme activity in the small intestine, total intestinal RNA was isolated and analyzed by Northern and dot-blot hybridization. The pattern of total lactase mRNA during development followed that of total lactase activity, suggesting that over this time span the level of lactase activity is primarily controlled at the transcriptional level. However, the magnitude of increase of total lactase activity during lactation compared to that of total lactase mRNA suggests that additional mechanisms are involved in regulating lactase levels. Analysis of the regional distribution of lactase mRNA along the small intestine at 14 days revealed that mRNA was high in the proximal three regions, but was dramatically lower in the distal regions. Total lactase activity, in contrast, displayed maximum activity in the mid-intestine with decreased levels both proximally and distally. Thus, lactase activity in the intestine appears to be regulated during development predominantly by transcriptional mechanisms, while alterations during lactation, and along the proximal to distal gradient, are the result of other control mechanisms.

Aging↗
PubMed1979

Calmodulin-binding proteins from brain and other tissues.

The calmodulin contents of rabbit brain, lung, kidney and liver, of bovine aorta and uterus, and of chicken gizzard have been determined. 2. The calmodulin in all of these tissues has been shown to be present in the form of very stable complexes with several other proteins. 3. A calmodulin-binding protein of mol.wt. 22 000 has been purified in high yield from bovine brain. It has been shown to interact with calmodulin and rabbit skeletal-muscle troponin C in a Ca2+-dependent manner. 4. The 22 000-mol.wt. protein inhibits the activation of bovine brain phosphodiesterase by calmodulin, but has very little affect on the activation of myosin light-chain kinase. 5. Calmodulin-binding proteins of mol.wts. 140000, 77000 and 61000 have also been partially purified from rabbit brain by affinity chromatography and have been shown to interact in a Ca2+-dependent manner with calmodulin. 6. The apparent molecular weights of the calmodulin-calmodulin-binding protein complexes, determined by gel filtration in the presence of 6M-urea, have been shown to be similar for most of the mammalian tissues examined. 7. By using 125I-labelled calmodulin, similar complexes have been demonstrated in rabbit skeletal muscle, although they are present at much lower concentrations.

Amino Acids↗
PubMed1979

Troponin C-like proteins (calmodulins) from mammalian smooth muscle and other tissues.

1. An acidic protein with properties similar to those of troponin C from rabbit skeletal muscle has been shown to be present in bovine and rabbit smooth muscles, chicken gizzard and rabbit liver, kidney and lung. 2. A simple new method involving the use of organic solvents is described for the purification of the troponin C-like proteins from various tissues. 3. The troponin C-like proteins can be distinguished from rabbit skeletal-muscle toponin C by their electrophoretic behaviour on polyacrylamide gels at pH 8.3 in the presence and absence of Ca2+. The troponin C-like proteins have been shown to form complexes with rabbit skeletal-muscle troponin I that migrate on electrophoresis in polyacrylamide gels. 4. Behaviour on electrophoresis, amino acid analysis and the patterns of CNBr digests on polyacrylamide gels indicate that the troponin C-like proteins from bovine uterus and aorta, rabbit uterus, and liver and chicken gizzard are very similar to, if not identical with, bovine brain modulator protein. 5. With bovine cardiac muscle the organic-solvent method yields a preparation consisting of roughly similar amounts of troponin C and troponin C-like protein. 6. By the isotope-dilution technique, troponin C-like protein has been shown to represent 0.42% of the total protein in rabbit uterus. 7. In homogenates of smooth muscle, rabbit lung, kidney and brain, the troponin C-like proteins form a complex with other protein (or proteins) that requires Ca2+ for its formation and that is not dissociated in 9M-urea.

Amino Acids↗
PubMed1979

Laboratory measures of copper metabolism in the differentiation of chronic active hepatitis and Wilson disease in children.

The accuracy of the serum ceruloplasmin level in distinguishing chronic active hepatitis from Wilson disease was compared to the 24-hour urinary copper excretion and hepatic copper content in 20 untreated patients with chronic active hepatitis and 25 with Wilson disease. Serum ceruloplasmin levels were decreased in five patients (25%) with chronic active hepatitis and were normal in seven patients (28%) with Wilson disease at the time of diagnosis. The 24-hour urinary copper excretion failed to provide accurate discrimination between the two groups, being elevated in all patients with Wilson disease and in five of eight patients with chronic active hepatitis studied. All patients with Wilson disease had hepatic copper levels greater than 400 microgram/gm dry weight, whereas patients with chronic active hepatitis had levels less than 300 microgram/gm dry weight. The discriminatory value of hepatic copper concentration makes this the most reliable test for differentiating chronic active hepatitis and Wilson disease in children and adolescents. The serum ceruloplasmin level may not be significantly accurate for definitive diagnosis in this age group.

Adolescent↗