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Biomedical subjects

R George

Publications and source records attributed to R George.

At least 73 records · Page 4Linked to original sources
PubMed1998

Estrogen regulation of adipose tissue lipoprotein lipase--possible mechanism of body fat distribution.

OBJECTIVE: The purpose of this study was to evaluate the regulation of lipoprotein lipase activity, protein mass, and messenger ribonucleic acid by estradiol. STUDY DESIGN: Premenopausal women not taking exogenous sex steroids had transdermal 17 beta-estradiol and placebo patches placed in the gluteal region during the early follicular phase of the menstrual cycle. Adipose biopsies were performed from beneath the patches. Adipose tissue lipoprotein lipase activity was determined by a radiometric assay, protein mass was determined by enzyme-linked immunosorbent assay, and messenger ribonucleic acid level was determined by Northern analysis. Comparisons between the treated and placebo sides were analyzed by nonparametric statistics. RESULTS: Adipose tissue from beneath the 17 beta-estradiol patch had significantly decreased lipoprotein lipase activity and extracellular protein mass than did adipose tissue from beneath the placebo patch. There was no difference in lipoprotein lipase messenger ribonucleic acid levels. CONCLUSION: Estrogen decreases lipoprotein lipase activity by a posttranscriptional modification of protein levels. A hypothesis of sex steroid regulation of body fat distribution is proposed.

Adipose Tissue↗
PubMed1998

Fluorescent amplified-fragment length polymorphism analysis of an outbreak of group A streptococcal invasive disease.

Fluorescent amplified-fragment length polymorphism (FAFLP) analysis was carried out for an outbreak of group A streptococcal (GAS) invasive disease. Streptococcal genomic DNAs were digested with endonucleases EcoRI and MseI, site-specific adaptors were ligated, and PCR amplification was carried out with an EcoRI adaptor-specific primer labelled with fluorescent dye. Amplified fragments of up to 600 bp in size were separated on a polyacrylamide sequencing gel which contained internal size markers in each lane. These data were automatically scanned and analyzed, fragments were precisely sized (+/-1 bp), and electropherograms were generated for each genome with GeneScan 2.1 software. All isolates were compared in this way. Among 27 GAS isolates examined, we found 18 FAFLP profiles, compared with 12 macrorestriction profiles by pulsed-field gel electrophoresis. FAFLP readily distinguished genotypes for two clones of GAS serotype M77 which were responsible for outbreaks of invasive disease in a care-of-the-elderly system. It provided an automated analysis of the whole genome of bacterial isolates. It was reproducible, more discriminatory, and capable of higher throughput than other molecular typing methods. Given agreed conditions, FAFLP would be reproducible between laboratories for rapid characterization of outbreak strains.

Aged↗
PubMed1998

Strengthening genetic services in primary care for Asian Americans and Pacific Islanders.

UNLABELLED: The Association of Asian Pacific Community Health Organizations (AAPCHO) is a national membership organization of community health centers (CHCs) that serve medically underserved Asian Americans and Pacific Islanders (AAPIs) with limited English-speaking proficiency and low income. OBJECTIVES: In 1995, AAPCHO was funded for a 3-year national genetics training project to improve genetics training among primary care providers at CHCs and strengthen linkages with tertiary genetic centers (TGCs). Three model linkages between CHCs and TGCs were documented on the coordination of genetic services for medically underserved AAPIs. METHODS: Guidelines were developed for three CHCs to document their genetic programs and linkages with TGCs. In addition, one clinic conducted a mail survey to assess understanding of prenatal genetic counseling sessions by patients that visited the clinic during the past 2 years. RESULTS: Model linkages between CHCs and TGCs to improve cultural and linguistic accessibility for patients include formal coordination between the CHCs and TGCs for the delivery of genetic services and the provision of varying levels of genetic services at the CHC. From the patient survey, there was a 59% response rate among 70 surveys mailed to former patients. The survey results showed that while a majority of patients understood and recalled key genetic concepts, one-fifth of patients experienced difficulty understanding their genetic counseling sessions. CONCLUSION: Based on model linkages between CHCs and TGCs and the patient satisfaction survey results, the following strategies are recommended to improve accessibility of genetic services for medically underserved AAPIs: (1) genetics education should be developed for all levels of health center staff; (2) counseling should be culturally sensitive and focus on key issues that must be conveyed for appropriate informed consent; (3) genetics education should employ the use of translated audiovisual aids and brochures to improve understanding; (4) genetic services should be coordinated between CHCs and TGCs to provide culturally and linguistically competent care for medically underserved AAPIs, and (5) financial mechanisms should be available to support genetic testing of patients and their families with little or no coverage for genetic services.

Journal Article↗
PubMed1998

The design of a vibration transducer to monitor the integrity of dental implants.

Bone-anchored titanium implants are being used increasingly to provide support for prostheses replacing missing teeth in edentulous and partially dentate patients. A technique is required to monitor bone formation at the implant-tissue interface during healing, and also to check whether there has been bone loss from around the top of the implant. One possible method is to screw a beam into the implanted fixture and to measure the first flexural resonance frequency of the resulting system. This resonance frequency is affected by both the exposed length of fixture and the stiffness of the interface between the implant and the bone. This paper describes the design of a beam-like transducer for clinical trials of the technique. The sensitivity of the transducer resonance frequency to the changes of interest is dependent on the thickness and length of the beam element. However, the choice of these dimensions is constrained by the need to avoid closely spaced resonances. The performance of different transducer shapes and the influence of the thickness and length of the beam element in the transducer has been studied. The results have been used to finalize a transducer design for the clinical trials.

Biomechanical Phenomena↗
PubMed1998

An analysis of the value of some antigen-antibody interactions used as diagnostic indicators in a treponemal Western blot (TWB) test for syphilis.

Densiometric quantitation and spreadsheet normalization were used to refine the parameters defining a treponemal Western blot (TWB) test for syphilis. Initially using 84 defined reactive and 105 defined non-reactive sera, we determined that the immune response to the 17 kDa antigen was the most critical of the following three candidate test determinants: the 47 kDa, 17 kDa and 15.5 kDa bands. In a second study using 124 cases of clinically diagnosed syphilis and 354 "normal" donors, a diluted serum sample was included as a minimal reactive control for the 17-kDa immune response. Reactivity to all three test determinants was obligatory for a test result to be interpreted as positive. Of the 124 cases of syphilis, 7 were nonreactive by TWB (sensitivity = 94%); of the 354 normal donors, 7 tested reactive (specificity = 98%). Forty (11%) normal serum samples had detectable but less than minimal reactivity to the 17 kDa band. Frequencies of immune response to a larger group of 12 antigens were tallied for the 124 clinically diagnosed cases of syphilis and an equal subset (124) of the normal group. In the normal subset, 72% and 52% of the samples had detectable reactivity to the 47 and 15.5 kDa antigens, respectively, while 10%, 5% and 3% reacted with the 17, 24 and 44.5 kDa antigens, respectively. Follow-up TWB testing of the clinically diagnosed cases revealed that previously untreated patients with primary or secondary syphilis were more likely to a show decrease in TWB reactivity than patients with latent symptoms who had been treated previously. As a diagnostic indicator of syphilis, the 17-kDa antigen was found to have the best combined attributes of sensitivity and specificity. Although, the highly specific 44.5 kDal and 24 kDal bands were often redundant as diagnostic indicators they are useful for the interpretation of borderline results. In addition, absence of the highly sensitive 47 and 15.5 kDa indicators should be useful in resolving some problem diagnoses.

Antibodies, Bacterial↗
PubMed1998

A randomized comparison of sequential-gradient calf compression with intermittent plantar compression for prevention of venous thrombosis in orthopedic trauma patients: preliminary results.

Trauma patients with fractures of the pelvis, acetabulum, or femur are at risk for deep venous thrombosis complicating the treatment of their injuries. This risk can be lessened with anticoagulant medications or with mechanical methods such as sequential pneumatic compression. However, many patients in this population group have contraindications to systemic anticoagulation and cannot use sequential limb compression devices because of leg injuries or appliances. Intermittent pneumatic compression of the plantar venous plexus is able to provide prophylaxis against deep venous thrombosis in many of these patients. We performed a prospective, randomized, controlled comparison between plantar compression and leg compression for prevention of deep venous thrombosis in an orthopedic trauma population of 124 patients. Patients were evaluated with duplex ultrasonagraphy at intervals after surgery. Both methods proved protective in comparison with reported rates in patients not given prophylaxis, and although the numbers were too small to give statistically meaningful results, we observed no significant difference in the thrombosis rate (4% for plantar compression versus 0% for leg compression). We conclude that foot pumps are an effective alternative to calf compression for prevention of deep venous thrombosis after a lower extremity fracture.

Adolescent↗
PubMed1998

Heterogeneity of guanylyl cyclase C expressed by human colorectal cancer cell lines in vitro.

In humans, guanylyl cyclase C (GCC) is expressed by mucosal cells lining the intestine, from the duodenum to the rectum, but not by extraintestinal tissues. Expression of GCC persists after mucosal cells undergo neoplastic transformation, and this protein has been identified in all primary and metastatic colorectal tumors examined to date, suggesting that GCC may be a highly specific biomarker for colorectal cancer. The utility of GCC as a diagnostic biomarker and therapeutic target is predicated, in part, on defining the variability of its expression in colorectal cancer cells. Similarly, the utility of this biomarker to define tumor burden in diagnosing, staging, and postoperative surveillance of patients is predicated on quantifying GCC expression in cancer cells in tissues and blood. The present studies examined the heterogeneity of GCC expression in eight human colorectal carcinoma cell lines in vitro representing the full spectrum of cytological differentiation. Quantification of GCC expression by ligand binding and stimulation of cGMP accumulation demonstrated that functional GCC expression is heterogeneous in different colorectal cancer cell lines. Qualitative reverse transcription (RT)-PCR demonstrated that all colorectal cancer cells examined expressed GCC mRNA. However, GCC expression varied 100-fold in different colorectal cancer cell lines, determined by a novel quantitative RT-PCR assay. Functional and molecular expressions of GCC were unrelated to the differentiation state of cancer cells. These studies suggest that GCC is heterogeneously expressed by colorectal cancer cells in vitro and suggest a role for quantitative RT-PCR analysis in the development of diagnostic tests using GCC as a biomarker for metastatic colorectal cancer.

Biomarkers, Tumor↗
PubMed1997

Vertical transmission of dengue.

Dengue, an important mosquito-borne flavivirus infection, is endemic in Southeast Asia. We describe two mothers who had acute dengue 4 and 8 days before the births of their infants. One mother had worsening of her proteinuric pregnancy-induced hypertension, liver dysfunction, and coagulopathy and required multiple transfusions of whole blood, platelets, and fresh frozen plasma. Her male infant was ill at birth, developed respiratory distress and a large uncontrollable left intracerebral hemorrhage, and died of multiorgan failure on day 6 of life. Dengue virus type 2 was isolated from the infant's blood, and IgM antibody specific to dengue virus was detected in the mother's blood. The second mother had a milder clinical course; she gave birth to a female infant who was thrombocytopenic at birth and had an uneventful hospitalization. Dengue virus type 2 was recovered from the mother's blood, and IgM antibody specific to dengue virus was detected in the infant's blood. This report highlights not only the apparently rare occurrence of vertical transmission of dengue virus in humans but also the potential risk of death for infected neonates.

Acute Disease↗
PubMed1997

Cloning and sequencing of the hyaluronate lyase gene from Propionibacterium acnes.

The hyaluronate lyase (hyaluronidase) gene from Propionibacterium acnes was cloned and sequenced. The gene was isolated on an EcoRI-generated 3-kb piece of DNA. Expression was less in Escherichia coli than in P. acnes; in E. coli, active enzyme was only cell associated and not secreted. The gene is 2256-pb long and codes for a protein of 82 kDa. Amino terminal sequencing of the protein of the partially purified gene indicated the presence of a 32-amino-acid leader sequence. The leader sequence showed a membrane-spanning domain and all of the features usually associated with the leader for a secreted protein. The amino acid sequence is predicted to share homology with the hyaluronidase enzymes from Streptococcus pneumoniae, Streptococcus agalactiae, and Staphylococcus aureus. A potential hyaluronate-binding domain was identified and antibody against this domain was inhibitory to the enzyme.

Amino Acid Sequence↗
PubMed1997

Dengue virus infection--the Malaysian experience.

Since dengue was first documented in Malaysia in 1902 and made notifiable in 1973, the disease pattern has changed from major outbreaks every four years to one of increasing trend yearly. The largest outbreak was seen in 1996 with 14,255 dengue cases reported and 32 deaths. The case fatality rate varied from a high of 10.43% in 1985 when dengue type 3 was the predominant type to a low of 1.29% when dengue type 1 predominated. Severe disease patterns have been observed with dengue 2 and 3 serotypes in the country. The clinical spectrum has also been changing and multisystem involvement with more severe manifestations are being seen. Liver involvement has been documented since 1987. Fulminant hepatitis with encephalopathy can resemble Reye's syndrome. Dengue type 3 has been isolated from liver biopsy specimens. Neurological manifestations can very from irritability, convulsions, coma to peripheral neuritis. The isolation of dengue viruses from cerebrospinal fluids recently strongly suggests that dengue viruses can be neurovirulent. Adult respiratory distress syndrome was seen in three children admitted with shock. Deaths were more frequent in children in the early period but since 1982, over 50% of deaths have occurred in patients over the age of 15 years.

Adult↗
PubMed1996

Structure of the O-specific polysaccharide from Burkholderia pickettii strain NCTC 11149.

A polymeric fraction (the putative O antigen) has been isolated from the lipopolysaccharide of the type strain of Burkholderia pickettii. The components of the polymer and their molar proportions were: L-rhamnose (3), 2-acetamido-2-deoxy-D-glucose (1), and O-acetyl (1). By means of NMR studies and chemical degradations, the basic repeating-unit of the polymer was identified as a linear tetrasaccharide of the structure shown. The O-acetyl group is probably located at position 2 of the 3-substituted alpha-L-Rha p. Similar polymers constitute O antigens in the related species Burkholderia solanacearum.

Acetylglucosamine↗
PubMed1996

Primary signet-ring cell carcinoma of the colon and rectum.

BACKGROUND: Primary signet-ring cell carcinoma of the colon and rectum is a rare form of adenocarcinoma of the large intestine. The purpose of this study was to help better define the natural history of this entity. METHODS: The medical records of 3,690 patients with colorectal cancer seen at The Roswell Park Cancer Institute between September 1971 and December 1993 were reviewed. We report on 29 patients with pathologic confirmation of primary signet-ring cell carcinoma. Patient demographics, clinical, and histologic parameters were evaluated. Survival was calculated by the Kaplan-Meier method. RESULTS: There was a nearly equal distribution of primary signet-ring cell carcinoma between the right colon and left colon/rectum. In most cases the tumors were > 6 cm, ulcerated, and involved the full thickness of the bowel wall. Nodal or metastatic disease was present in 21 of 29 patients (72%) at the time of diagnosis. Four patients (14%) had synchronous colorectal adenocarcinomas. Twenty-two patients died of disease progression. At the time of death, two patients (9%) had failed in the liver, whereas all 22 patients had peritoneal carcinomatosis. CONCLUSIONS: Patients with primary signet-ring cell colorectal carcinoma frequently present with late-stage disease. In 23 of 29 patients, the disease rapidly recurred or progressed. Peritoneal carcinomatosis is the most common pattern of failure.

Adolescent↗
PubMed1996

High-resolution genotyping elucidates the epidemiology of group A streptococcus outbreaks.

Streptococcus pyogenes strains were genotyped by a combination of molecular methods for high- resolution epidemiologic studies of disease outbreaks. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the emm gene is reported. Alone or in conjunction with other molecular techniques (16S ribotyping, pulsed-field gel electrophoresis, and detection of exotoxin genes), PCR-RFLP could differentiate outbreak-related strains from contemporaneous background strains of the same M serotype. Three outbreaks were studied: pharyngitis in a boarding school (serotype M5), cross-infection in a hospital burn unit (serotype M76), and severe invasive disease in two elderly care homes (serotype R28). It was possible, for example, to identify within serotype R28 a clone with particular potential for invasive disease. In all cases, the four molecular methods yielded complementary results that were hierarchically related. Strains could be assigned to the outbreak or the background in a precise, reproducible, and rapid manner.

Antigens, Bacterial↗
PubMed1996

The insulin-mimetic agent vanadate promotes receptor endocytosis and inhibits intracellular ligand-receptor degradation by a mechanism distinct from the lysosomotropic agents.

Vanadate (sodium orthovanadate) is an insulin-mimetic agent and phosphotyrosine phosphatase inhibitor that has been proposed as a potential therapeutic agent for diabetes. We previously reported that vanadate decreased the number of cell-surface insulin receptors but inhibited receptor degradation in cultured lymphocytes (IM-9) (1). To determine whether vanadate affected receptors without intrinsic tyrosine kinase activity, its effects on LDL and transferrin receptors and their ligands were examined. Vanadate exposure resulted in a dose- and time-dependent decrease in LDL binding to cultured human fibroblasts associated with a decrease in cell surface receptor number while total solubilized cell LDL receptors increased. Vanadate also inhibited the LDL-mediated downregulation of total cellular LDL receptors in the absence and presence of cycloheximide consistent with an inhibition of LDL receptor degradation. In the case of the ligand, vanadate augmented the accumulation of intact 125I-LDL associated with an inhibition of up to 80% of the ability of LDL to decrease cholesterol synthesis. Since these actions were similar to the effects of lysosomotropic agents, we examined the effect of vanadate on intraendosomal pH using the fluorescent probe acridine orange. In contrast with chloroquine and NH4Cl, vanadate did not neutralize the pH of the acidic intracellular compartment. Furthermore, after a transient insulin-like effect, chronic exposure to vanadate diminished 125I-diferric transferrin binding to rat adipocytes. In contrast with the inhibitory action of NH4Cl, intracellular 59Fe uptake remained unaffected and was proportional to cell-surface binding capacity in the presence of vanadate. These data demonstrate a chronic effect of vanadate to promote the accumulation of intracellular receptors and to inhibit ligand and receptor degradation. The latter effect is not mediated by pH changes, appears to be localized to a late endosomal/lysosomal compartment, and suggests a possible role for tyrosine dephosphorylation in the regulation of receptor-ligand degradation.

Adipocytes↗
PubMed1996

Dengue encephalitis: a true entity?

Involvement of the central nervous system in dengue fever and dengue hemorrhagic fever has always been thought to be secondary to vasculitis with resultant fluid extravasation, cerebral edema, hypoperfusion, hyponatremia, liver failure, and/or renal failure. Thus, the condition has been referred to as dengue encephalopathy. Encephalitis or direct involvement of the brain by the virus was thought to be unlikely. This paper reports on six children who were seen over a period of two years presenting on the second or third day of illness with dengue encephalitis. The diagnosis was based upon a clinical picture of encephalitis and confirmed by cerebrospinal fluid (CSF) microscopy and electroencephalography changes. All six cases were confirmed dengue infections. Dengue 3 virus was isolated from the CSF of four cases and in one case, dengue 2 was detected by the polymerase chain reaction in both the CSF and blood. In the sixth case, virologic evidence was negative but dengue immunoglobulin M was detected in the CSF and blood. Since the onset of encephalitis appears early in the course of illness coinciding with the viremic phase, we postulate that the virus crosses the blood-brain barrier and directly invades the brain causing encephalitis. This study provides strong evidence that dengue 2 and 3 viruses have neurovirulent properties and behave similarly to other members of the Flaviviridae.

Antibodies, Viral↗