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Biomedical subjects

G Klein

Publications and source records attributed to G Klein.

At least 73 records · Page 4Linked to original sources

Long-term effects of in-hospital cardiac rehabilitation on the cardiac risk profile. A case-control study in pairs of siblings with myocardial infarction.

AIMS: In the general population, measures for secondary prevention of myocardial infarction are poorly utilized. Our aim was therefore to analyse whether post-myocardial infarction in-hospital rehabilitation and education programmes improve the subsequent utilization of preventive strategies. METHODS AND RESULTS: We screened 93 500 patient charts in cardiac rehabilitation clinics to identify a myocardial infarction patient with a sibling, who likewise had a myocardial infarction prior to the age of 60 years but was discordant with respect to the participation in cardiac in-hospital rehabilitation. In 92 such sibling pairs the coronary risk profile was studied by standardized questionnaire, biochemical measurements and physical examination. At the time of the acute myocardial infarction, both groups showed an equal risk factor distribution. However, at follow-up (on average 5.5 years after myocardial infarction), rehabilitation-siblings presented with significantly lower systolic (137+/-2 vs 150+/-3 mmHg, P<0.01) and diastolic blood pressure (82+/-1 vs 89+/-1 mmHg, P<0.01). Antihypertensive drug therapy resulted more often in effective (<or=140/90 mmHg) control of blood pressure (58% vs 29%, P<0.01). Blood lipid levels and smoking prevalence tended to be lower in rehabilitation-siblings. Significantly fewer rehabilitation-siblings presented with two or more modifiable risk factors (OR 0.36 (CI 0.17-0.76); P<0.01). There was a strong tendency towards fewer recurrent cardiac events (re-myocardial infarction, coronary angioplasty, coronary artery bypass grafting) during follow-up in rehabilitation-siblings (OR 0.57 (CI 0.31-1.04); P=0.07). CONCLUSION: An in-hospital programme for cardiac rehabilitation may successfully encourage therapy to modify risk factors and thus enhance the long-term implementation of secondary prevention.

Case-Control Studies↗

Identification of important amino acid residues that modulate binding of Escherichia coli GroEL to its various cochaperones.

Genetic experiments have shown that the GroEL/GroES chaperone machine of Escherichia coli is absolutely essential, not only for bacterial growth but also for the propagation of many bacteriophages including lambda. The virulent bacteriophages T4 and RB49 are independent of the host GroES function, because they encode their own cochaperone proteins, Gp31 and CocO, respectively. E. coli groEL44 mutant bacteria do not form colonies above 42 degrees nor do they propagate bacteriophages lambda, T4, or RB49. We found that the vast majority (40/46) of spontaneous groEL44 temperature-resistant colonies at 43 degrees were due to the presence of an intragenic suppressor mutation. These suppressors define 21 different amino acid substitutions in GroEL, each affecting one of 13 different amino acid residues. All of these amino acid residues are located at or near the hinge, which regulates the large en bloc movements of the GroEL apical domain. All of these intragenic suppressors support bacteriophages lambda, T4, and RB49 growth to various extents in the presence of the groEL44 allele. Since it is known that the GroEL44 mutant protein does not interact effectively with Gp31, the suppressor mutations should enhance cochaperone binding. Analogous intragenic suppressor studies were conducted with the groEL673 temperature-sensitive allele.

Alleles↗

Attenuation of posttraumatic muscle catabolism and osteopenia by long-term growth hormone therapy.

OBJECTIVE: To determine whether the beneficial effects of growth hormone persist throughout the prolonged hypermetabolic and hypercatabolic response to severe burn. SUMMARY BACKGROUND DATA: The hypermetabolic response to severe burn is associated with increased energy expenditure, insulin resistance, immunodeficiency, and whole body catabolism that persists for months after injury. Growth hormone is a potent anabolic agent and salutary modulator of posttraumatic metabolic responses. METHODS: Seventy-two severely burned children were enrolled in a placebo-controlled double-blind trial investigating the effects of growth hormone (0.05 mg/kg per day) on muscle accretion and bone growth. Drug or placebo treatment began on discharge from the intensive care unit and continued for 1 year after burn. Total body weight, height, dual-energy x-ray absorptiometry, indirect calorimetry, and hormone values were measured at discharge, then at 6 months, 9 months, and 12 months after burn. Results were compared between groups. RESULTS: Growth hormone subjects gained more weight than placebo subjects at the 9-month study point; this disparity in weight gain continued to expand throughout the remainder of the study. Height also increased in the growth hormone group compared with controls at 12 months. Change in lean body mass was greater in those treated with growth hormone at 6, 9, and 12 months. Bone mineral content was increased at 9 and 12 months; this was associated with higher parathormone levels. CONCLUSIONS: Low-dose recombinant human growth hormone successfully abates muscle catabolism and osteopenia induced by severe burn.

Adolescent↗

N-cadherin is developmentally regulated and functionally involved in early hematopoietic cell differentiation.

The cadherins, an important family of cell adhesion molecules, are known to play major roles during embryonic development and in the maintenance of solid tissue architecture. In the hematopoietic system, however, little is known of the role of this cell adhesion family. By RT-PCR, western blot analysis and immunofluorescence staining we show that N-cadherin, a classical type I cadherin mainly expressed on neuronal, endothelial and muscle cells, is expressed on the cell surface of resident bone marrow stromal cells. FACS analysis of bone marrow mononuclear cells revealed that N-cadherin is also expressed on a subpopulation of early hematopoietic progenitor cells. Triple-color FACS analysis defined a new CD34(+) CD19(+) N-cadherin(+) progenitor cell population. During further differentiation, however, N-cadherin expression is lost. Treatment of CD34(+) progenitor cells with function-perturbing N-cadherin antibodies drastically diminished colony formation, indicating a direct involvement of N-cadherin in the differentiation program of early hematopoietic progenitors. N-cadherin can also mediate adhesive interactions within the bone marrow as demonstrated by inhibition of homotypic interactions of bone-marrow-derived cells with N-cadherin antibodies. Together, these data strongly suggest that N-cadherin is involved in the development and retention of early hematopoietic progenitors within the bone marrow microenvironment.

Bone Marrow Cells↗

Allele-specific loss or imbalance of chromosomes 9, 15, and 16 in B-cell tumors from interspecific F1 hybrid mice carrying Emu-c-myc or N-myc transgenes.

Mice carrying an immunoglobulin enhancer (Emu-) linked c- or N-myc transgene develop fatal monoclonal or oligoclonal pre-B or B-cell lymphomas. This indicates that, beside the Emu-activated myc gene, additional genetic changes are required for tumor development. To trace these additional changes, we carried out a genome-wide search for loss of heterozygosity (LOH) and allelic imbalance (AI). This was done at 53 microsatellite markers in a panel of 34 lymphomas and four plasmacytomas from c- or N-myc transgene carrying (BALB/c x Mus spretus)F1 hybrids. An additional 43 lymphomas and three plasmacytomas from non-transgenic F1 mice were also investigated. Losses of one or more spretus-derived chromosome 9 markers were detected in 19 of 23 (83%) of the lymphomas, but in none of the four plasmacytomas that developed in N-myc F1 mice. No LOH-9 was found in any of the 11 lymphomas from Emu-c-myc F1 mice and only in 1 of 46 (2%) tumors derived from non-transgenic (BALB/c x spretus)F1 hybrid controls. These results suggest that a gene on spretus chromosome 9 confers resistance to the development of N-myc but not c-myc-induced lymphomas. AI of chromosome 15 markers (AI-15) was detected in 57 of 77 (74%) lymphomas and in 5 of 7 (72%) plasmacytomas, independently of the transgenic status and the mode of induction. All of the lymphomas and plasmacytomas with AI-15 revealed a relative gain of the spretus-derived D15Mit6 allele (located at 13.7 cM from the centromere), together with a gain of the BALB/c allele of the more distal (29.6 cM) D15Mit64 marker, suggesting somatic recombination. LOH in the region close to c-myc was detected in a proportion of tumors with AI-15. The observation of complex genetic alterations includes somatic recombination, AI and LOH involving chromosome 15 in tumors induced by a myc transgene. This indicates that at least two genes in addition to c-myc on this chromosome can be involved in lymphoma development.

Allelic Imbalance↗

Characterization and functional analysis of laminin isoforms in human bone marrow.

Laminins are a family of disulfide-linked heterotrimeric proteins consisting of 3 different subunits termed alpha, beta, and gamma chains. Combinations of 11 characterized laminin subunits (alpha 1-alpha 5, beta 1-beta 3, and gamma 1-gamma 3) generate at least 12 laminin isoforms, which can serve different functions. Although expression of laminin in the hematopoietic microenvironment has been known for many years, the nature of the laminin isoforms present in the human bone marrow is poorly characterized. The present study attempts to clarify this issue. Reverse transcriptase-polymerase chain reaction analysis of human bone marrow stromal cells suggested the expression of many laminin isoforms in the marrow. Northern blot and immunoblot analysis, however, showed that laminin-8/9 and laminin-10/11 are the most abundant laminin isoforms synthesized by human bone marrow stromal cells. Other isoforms, if present, certainly play a minor role in the hematopoietic microenvironment. Functionally, laminin-10/11 preparations showed strong adhesive interactions with human CD34(+) cell lines. Antibodies against the beta 1 integrin subunit inhibited these interactions. Other laminin isoforms, especially laminin-1 and laminin-2/4, showed only weak or no adhesive interactions with the hematopoietic cell lines tested, explaining former negative results. In addition to its adhesion-mediating properties, laminin-10/11 preparations also showed a mitogenic activity for human hematopoietic progenitor cells. Taken together, these data suggest that laminin in the bone marrow plays a hitherto unexpected important function in the development of hematopoietic progenitor cells. (Blood. 2000;96:4194-4203)

Blotting, Western↗

Inactivation of the human fragile histidine triad gene at 3p14.2 in monochromosomal human/mouse microcell hybrid-derived severe combined immunodeficient mouse tumors.

We have previously shown that inoculation of human chromosome 3 (chr3)/A9 mouse fibrosarcoma microcell hybrids (MCHs) into severe combined immunodeficient (SCID) mice was followed by the regular elimination of some 3p regions whereas a 3q region was retained even after prolonged mouse passage. Using this approach, referred to as the elimination test (Et), we have defined a common eliminated region (CER) of approximately 7 cM at 3p21.3 that was absent in all of the 27 tumors generated from five MCHs. Later, CER was reduced to a 1-Mb region, designated as CER1. Another eliminated region (ER2) at 3p21.1-p14.2 was absent in 21 of the 27 tumors. ER2 borders at but does not include the fragile histidine triad (FHIT) gene, considered as a putative tumor suppressor gene. In the present work, two new and two previously studied MCHs, and 13 derived SCID mouse tumors were analyzed by fluorescence in situ hybridization (FISH) chromosome painting and by PCR, using 72 chr3p-specific and 11 chr3q-specific markers. Nine tumors generated from three MCHs that carried cytogenetically normal chr3, remained PCR-positive for all of the chr3 markers tested. Designated as "PCR+" tumors, they were examined by reverse transcription (RT)-PCR, together with four of six previously studied tumors derived from MCH910.7, which carried a del(3)(pter-p21.1), for the expression of 14 human genes: 5 genes within CER1 (LIMD1, CCR1, CCR2, CCR3, CCR5), 5 genes located within regions that were homozygously deleted in a variety of carcinomas (ITGA4L, LUCA1, PTPRG, FHIT, DUTT1), and 4 other genes in chr3p (VHL, MLH1, TGM4, UBE1L). We found that VHL, MLH1, ITGA4L, LIMD1, UBE1L, LUCA1, PTPRG, and DUTT1 were expressed in the MCH lines in vitro and also in the derived SCID tumors. No transcripts that originated from the four CCR genes or from TGM4 could be detected in any of the MCH lines. Alone among the 14 genes examined, FHIT showed a tumor growth-associated change. It was expressed in vitro in five of seven MCH lines. Nine of 13 derived tumors had no FHIT transcript. The remaining 4 expressed a truncated mRNA and a reduced amount of the full-length mRNA. We have previously found that FHIT was deleted at the DNA level in 17 of 21 tumors derived from four MCHs. The remaining 4 of 21 had no FHIT transcript. Our compiled data show that FHIT was either physically or functionally impaired in all 34 of the 34 analyzed tumors. Variants with deleted or down-regulated FHIT have a selective growth advantage.

Acid Anhydride Hydrolases↗

[Secondary prevention in coronary patients after inpation rehabilitation].

BACKGROUND AND OBJECTIVE: [corrected] Data on impressive improvements in the prognosis and clinical progress of patients with coronary heart disease (CHD) through consistent reduction of risk factors and administration of cardioprotective drugs have led to the formulation of guidelines by professional associations. The aim of this prospective, multicenter cohort study (PIN: Post-Infarkt-Nachsorge = Postinfarction Aftercare) was to determine the extent to which these recommendations are implemented in the long term in patients who have had an acute coronary event and are undergoing rehabilitation therapy. PATIENTS AND METHODS: From January to May 1997, 2441 patients at 18 rehabilitation centers (22% women, 65 +/- 10 years; 78% men, 60 +/- 10 years) with diagnosed CHD following an acute cardiac event were enrolled in the study. Risk factors and pharmacologic therapy were recorded by the patients' GPs on a standardized questionnaire on admission to and discharge from rehabilitation therapy (RT) as well as after 3, 6, and 12 months. New clinical events were documented by questioning the patients and their attending physicians. RESULTS: After an impressive reduction of cardiovascular risk factors during RT, the percentage of patients with blood pressure values > 140/90 mmHg rose from 8% to 25% after 12 months (p < 0.001). 11% vs 17% of the patients had glucose levels > 140 mg/dl and 29% vs 51% had total cholesterol levels > 200 mg/dl (p < 0.001). 5% of the patients smoked at the time of discharge, 10% after one year. Compared to the time of discharge, significantly fewer beta-receptorblockers, lipid-lowering drugs, angiotensin converting-enzyme (ACE) inhibitors, and acetylsalicylic acid were prescribed. During follow-up observation, 886 patients suffered one or more clinical events, of which 69% occurred in the first six months. CONCLUSION: The interventional success of in-patient rehabilitation therapy is not sustained in the long term. This could be due to deficient implementation of guidelines for the secondary prevention of CHD, as the cardiovascular risk factors exceed pathological limits in a large proportion of patients and the prescription of cardioprotective medications is less than optimal.

Aftercare↗

Correlation of mutations of the SH2D1A gene and epstein-barr virus infection with clinical phenotype and outcome in X-linked lymphoproliferative disease.

The purposes of this study were to determine the frequency of mutations in SH2D1A in X-linked lymphoproliferative disease (XLP) and the role of SH2D1A mutations and Epstein-Barr virus (EBV) infection in determining the phenotype and outcome of patients with XLP. Analysis of 35 families from the XLP Registry revealed 28 different mutations in 34 families-large genomic deletions (n = 3), small intragenic deletions (n = 10), splice-site (n = 3), nonsense (n = 3), and missense (n = 9) mutations. No mutations were found in 25 males, so-called sporadic XLP (males with an XLP phenotype after EBV infection but no family history of XLP) or in 9 patients with chronic active EBV syndrome. Of 304 symptomatic males in the XLP Registry, 38 had no evidence of EBV infection at first clinical manifestation. When fulminant infectious mononucleosis (FIM) was excluded, there was no statistical difference in the frequency of EBV infectivity in the other XLP phenotypes. Furthermore, there was no difference at age of first clinical manifestation between EBV(+) and EBV(-) males or in survival when patients with FIM were excluded. In conclusion, it was found that mutations in the SH2D1A gene are responsible for XLP but that there is no correlation between genotype and phenotype or outcome. It was also found that though EBV infection often results in FIM, it is unnecessary for the expression of other manifestations of XLP, and it correlates poorly with outcome. These results suggest that unidentified factors, either environmental or genetic (eg, modifier genes), contribute to the pathogenesis of XLP.

Alternative Splicing↗

SH2D1A and SLAM protein expression in human lymphocytes and derived cell lines.

The gene defect responsible for the X-linked lymphoproliferative disease (XLP) is associated with an impaired control of Epstein-Barr virus (EBV) infection. The gene has been recently identified and the encoded protein (designated SH2D1A, DSHP or SAP) was characterized. It is a 128 amino acid (aa) protein, containing a single Src homology 2 (SH2) domain. It interacts with signaling lymphocytic activation molecule (SLAM) expressed on the surface of activated T and B cells. We show that activated T, but not activated B, cells express the SH2D1A protein. NK cells express the protein as well. Tumor lines originating from B, T or NK cells exhibited similar SH2D1A protein expression as the corresponding normal cells, with some notable exceptions. EBV-carrying, tumor phenotype representative (type I), but not EBV-carrying lymphoblastoid cell line (LCL)-like (type III) or EBV-negative Burkitt lymphoma (BL) lines expressed SH2D1A. The phenotypic switch from type I to type III in the EBV-carrying BL line Mutu was associated with a down-regulation of SH2D1A and up-regulation of SLAM. In contrast to normal ex vivo and long-term activated NK cells, 2 of 3 NK leukemia lines expressed SLAM. All 3 lines expressed SH2D1A, like their normal counterparts.

Amino Acid Sequence↗

Differences in the immunogenicity of latent membrane protein 1 (LMP1) encoded by Epstein-Barr virus genomes derived from LMP1-positive and -negative nasopharyngeal carcinoma.

We have previously shown that an EBV-encoded latent membrane protein 1 (LMP1) gene derived from a nude mouse-propagated nasopharyngeal carcinoma (NPC) tumor and expressed in nonimmunogenic murine mammary carcinoma S6C cells failed to convey immunogenicity (rejectability) in syngeneic mice, whereas the corresponding B-cell derived LMP1 gene made the mice highly immunogenic. This raised the question of whether LMPL-expressing NPCs have been selected for low immunogenicity at the viral gene expression level. If so, LMP1-negative tumors that carry highly methylated LMP1 regulatory sequences may not have been exposed to a similar immunoselection. In the present study, we have compared LMP1 genes derived from two LMP1-positive NPCs and two LMP1-negative NPCs. All four genes were expressed in S6C cells in parallel with the previously tested isolates from a B-cell (B95-8)-derived and a nude mouse-propagated NPC (Cao)-derived gene. As in the previous study, we have found that the B-cell-derived LMP1 isolate was highly immunogenic. LMP1-positive tumor-derived isolates were poorly immunogenic, whereas the isolates from the LMP1-negative NPC tumor had intermediate immunogenicity. Sequence data revealed that LMP1 genes from LMP1-expressing NPC had 16 amino acid substitutions, whereas LMP1 from non-LMP1-expressing NPC had only 9 amino acid changes in the coding region. Three of the changes were at shared sites, but with different modifications. The fact that the gene from non-LMP1-expressing NPC mutated at a low frequency but was more immunogenic than the LMP1 gene derived from LMP1-expressing NPC, which was highly mutated but less immunogenic, favors the idea that LMP1-positive tumors escape immunosurveillance in immunocompetent hosts by either a selective down-regulation of LMP1 expression, methylation in the LMP1 promoter sequence, or mutation of LMP1 in LMP1-expressing samples.

Animals↗

[Better understanding of the biology of cancer cells].

Most forms of cancer arise through a Darwinian evolutionary process. The natural selection that ultimately leads to cancer takes place in somatic tissues although it may be triggered by inherited mutations in a small but significant minority. It favors the growth of clones and subclones that are less and less responsive to normal intra- and extracellular growth control mechanisms. The development of molecular biology has led to the identification of many genes that participate in this somatic evolution. They belong to the following groups: Oncogenes, constitutively activated by structural and/or regulatory changes that drive the cell to continuous proliferation; Tumor suppressor genes, that can inhibit the illegitimately activated cell cycle. They contribute to tumor development by loss mutations or permanent down-regulation, e.g. by methylation; Apoptosis inhibitory genes that can contribute to tumor development by raising the apoptotic threshold, and apoptosis promoting genes that can favor the growth of apoptosis prone tumor cells by their loss or inactivation; DNA repair genes whose inactivation can counteract the normal elimination of cells that carry potentially cancer promoting mutations. Inherited mutations in DNA repair genes can lead to familial cancer syndromes. Immortalizing genes that counteract cellular senescence; Angiogenesis promoting genes whose products may stimulate the vascular supply of tumors; Genes whose structural or functional changes may facilitate the escape of tumor cells from immune rejection; The multi-step development of individual tumors can encompass changes in most or all of these genes. They occur independently of each other and without any fixed order or timing. Tumor emancipation from growth control can therefore proceed along various pathways. It follows that each tumor must be regarded as a biologically unique individual.

Apoptosis↗

CoQ10 fails to protect brain against focal and global ischemia in rats.

OBJECTIVE: Release of oxygen free radicals occurs following cerebral ischemia. Studies show that oxygen free radicals mediate ischemic brain injury. CoQ10 is a potent free radical scavenger and may offset brain injury associated with reperfusion. We tested exogeneous CoQ10 as a neuroprotectant in rats following both global and focal ischemic insults. METHODS: Rats were subjected to either 4-vessel occlusion ischemia (4-VO, 10 min occlusion, 7-day survival) or middle cerebral artery occlusion (MCAO, 120 min-occlusion, 22.5 h survival). Regional cerebral blood flows (rCBF) and physiological variables such as blood pressure, pO2, pCO2, plasma glucose and hematocrit were monitored and measured in focal ischemia. The animals were randomized to receive treatments of either phosphate buffered saline (PBS) vehicle or CoQ10 following global or focal ischemia. Injection times were at the end of ischemia and 3 h later for both models of ischemia. Histological outcomes are expressed as a percentage of hippocampal CA(1) cell injury in global ischemia or percentage of cortical infarct over that of non-ischemic hemisphere in focal ischemia. RESULTS: In global ischemia, animals treated with PBS vehicle and CoQ10 had 86+/-5% (n=8) and 83+/-10% (n=8), respectively, of hippocampal CA(1) cell injury (P>0.05). The percentage of infarct volumes in animals following focal ischemia were 23+/-9% (control, n=10) and 25+/-9% (CoQ10, n=10). There were no temperature or physiological differences between the two treatment groups. CONCLUSION: Acute treatment with CoQ10 via intraperitoneal injection does not prevent neuronal injuries following global and focal ischemia.

Animals↗

[Guidelines for lowering lipids are too infrequently observed. Results of a retrospective study of coronary heart disease patients].

UNLABELLED: The aim of this retrospective analysis was to investigate adherence to treatment guidelines in the secondary prevention of coronary heart disease. 3720 CHD patients treated in 591 doctor's offices throughout Germany were investigated. End points were serum lipid levels at week-6, i.e. screening investigation, and 5 weeks after discontinuation of the lipid-lowering medication (week-1). 3383 of the 3720 (90.9%) patients had LDL-C levels > = 115 mg/dl, and 3563 (95.8%) > = 100 mg/dl. At week-6 mean LDL-C was 167.7 +/- 43.5 and mean total cholesterol was 258.8 +/- 47.8 mg/dl. 5 weeks after discontinuation of lipid-lowering treatment, mean LDL-C increased by 5.6%, and mean total cholesterol by 3.7% in comparison with baseline at week-6. 2346 (69.3%) of the patients with LDL-C > = 115 at week-6 did not receive any prior lipid-lowering medication. Also, patients receiving lipid-lowering medication demonstrated an insufficient lipid decrease (only 14.4% of all treated patients had LDL-C levels < 115 mg/dl, and only 6.8% had levels < 100 mg/dl. CONCLUSION: So far, lipid-lowering guidelines for the secondary prevention of CHD are not being adequately implemented. Appropriate action to remedy this situation (e.g. establishment of Disease Management Programs) is needed. The aggressive use of lipid-lowering drugs is a must if the goals of the treatment guidelines are to be met, and morbidity and mortality of CHD lowered.

Anticholesteremic Agents↗

Gilbert's syndrome and hyperbilirubinaemia in ABO-incompatible neonates.

We asked whether UDP glucuronosyltransferase (UGT) gene promoter polymorphism (Gilbert's syndrome) would increase hyperbilirubinaemia in direct Coombs' negative ABO-incompatible neonates, as seen in other combinations with this condition. 40 ABO-incompatible and 344 ABO-compatible controls had an allele frequency of 0.35 for the variant promoter gene. The incidence of hyperbilirubinaemia was significantly higher only in the former who were also homozygotes for the variant UGT promoter, compared with ABO-incompatible babies homozygous for the normal UGT promoter (43% vs 0, p=0.02), and with ABO-compatible controls of all UGT genotypes combined (relative risk 5.65, 95% CI 2.23-14.31). Gilbert's syndrome is a determining factor for neonatal hyperbilirubinaemia ABO incompatibility.

ABO Blood-Group System↗