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Biomedical subjects

E George

Publications and source records attributed to E George.

At least 19 recordsLinked to original sources
PubMed2002

A comparison of experimental, theoretical, and numerical simulation Rayleigh-Taylor mixing rates.

We present a Rayleigh-Taylor mixing rate simulation with an acceleration rate falling within the range of experiments. The simulation uses front tracking to prevent interfacial mass diffusion. We present evidence to support the assertion that the lower acceleration rate found in untracked simulations is caused, at least to a large extent, by a reduced buoyancy force due to numerical interfacial mass diffusion. Quantitative evidence includes results from a time-dependent Atwood number analysis of the diffusive simulation, which yields a renormalized mixing rate coefficient for the diffusive simulation in agreement with experiment.

Journal Article↗
PubMed2002

V-Y advancement flap and composite graft for alar-groove reconstruction.

A one-stage procedure combining a V-Y advancement flap with a composite graft for the reconstruction of alar-lobule and alar-groove defects is described. After tumour resection, a V-Y flap is advanced and retained at the level of the piriform margin to fill the dead space. To provide vascular support to the composite graft and to recreate the alar groove the advancing edge of the flap is de-epithelialised. In the same stage the composite graft is harvested and placed into the alar defect. A series of 12 patients underwent this procedure, with good results.

Aged↗
PubMed2002

Hemodynamic monitoring.

The goal of hemodynamic monitoring is to maintain adequate tissue perfusion. Classical hemodynamic monitoring is based on the invasive measurement of systemic, pulmonary arterial and venous pressures, and of cardiac output. Since organ blood flow cannot be directly measured in clinical practice, arterial blood pressure is used, despite limitations, as estimate of adequacy of tissue perfusion. A mean arterial pressure (MAP) of 70 mm Hg may be considered a reasonable target, associated with sign of adequate organ perfusion, in most patients. In the approach to hypotension, which is the most common cause of hemodynamic instability in critical ill patients, increasing levels of monitoring may be used. Assuming that central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) are adequate estimates of the volume of the systemic and pulmonary circulation respectively, the following decision tree is suggested: 1) make a working diagnosis based on the relationship between pressure (CVP and PAOP) and cardiac output or stroke volume (CO or SV); 2) consider conditions that may alter reliability of CVP and PAOP in estimate adequately circulating volumes such as abnormal pressure/volume relationship (compliance) of the RV or LV, increased intrathoracic pressure (PEEP, autoPEEP, intra-abdominal pressure), valvular heart disease (mitral stenosis); 3) look at the history; 4) separating RV and LV by reciprocal variations of CVP, PAOP and SV. CVP is often used as sole parameter to monitor hemodynamic. However CVP alone may not differentiate between changes in volume (different venous return curve) or changes in contractility (different starling curve). Finally, other techniques such as echocardiography, transesophageal Doppler and volume-based monitoring system are now available.

Blood Pressure↗
PubMed2001

Gene mutations in the succinate dehydrogenase subunit SDHB cause susceptibility to familial pheochromocytoma and to familial paraganglioma.

The pheochromocytomas are an important cause of secondary hypertension. Although pheochromocytoma susceptibility may be associated with germline mutations in the tumor-suppressor genes VHL and NF1 and in the proto-oncogene RET, the genetic basis for most cases of nonsyndromic familial pheochromocytoma is unknown. Recently, pheochromocytoma susceptibility has been associated with germline SDHD mutations. Germline SDHD mutations were originally described in hereditary paraganglioma, a dominantly inherited disorder characterized by vascular tumors in the head and the neck, most frequently at the carotid bifurcation. The gene products of two components of succinate dehydrogenase, SDHC and SDHD, anchor the gene products of two other components, SDHA and SDHB, which form the catalytic core, to the inner-mitochondrial membrane. Although mutations in SDHC and in SDHD may cause hereditary paraganglioma, germline SDHA mutations are associated with juvenile encephalopathy, and the phenotypic consequences of SDHB mutations have not been defined. To investigate the genetic causes of pheochromocytoma, we analyzed SDHB and SDHC, in familial and in sporadic cases. Inactivating SDHB mutations were detected in two of the five kindreds with familial pheochromocytoma, two of the three kindreds with pheochromocytoma and paraganglioma susceptibility, and 1 of the 24 cases of sporadic pheochromocytoma. These findings extend the link between mitochondrial dysfunction and tumorigenesis and suggest that germline SDHB mutations are an important cause of pheochromocytoma susceptibility.

Amino Acid Sequence↗
PubMed2001

Measles antibody responses after early two dose trials in Guinea-Bissau with Edmonston-Zagreb and Schwarz standard-titre measles vaccine: better antibody increase from booster dose of the Edmonston-Zagreb vaccine.

In Guinea-Bissau, children were randomised at 6 months of age to receive either two doses of standard-titre measles vaccine at 6 and 9 months of age or an inactivated polio vaccine at 6 months and standard-titre measles vaccine at 9 months of age. During the first 5 months, children received Edmonston-Zagreb (EZ) vaccine and during the following 11 months, the Schwarz (SW) vaccine. Five percent of the mothers, 74% of children at 6 months of age, and 92% of unvaccinated children at 9 months of age had unprotective levels (<125 mIU/ml) of measles antibodies. Among children receiving EZ vaccine, 1% were unprotected at 18 months of age after either two (3/240) or one (3/211) doses of vaccine, the geometric mean measles antibody titre (GMT) being approximately 1550 mIU/ml in both groups. Among those receiving SW vaccine 9% (34/365) and 3% (9/310) were unprotected at 18 months of age in the two-dose and the one-dose groups (RR = 3.21 (95% confidence interval (CI) 1.56-6.58)), respectively. The GMT was higher after one dose of SW vaccine at 9 months of age (2491 mIU/ml) than after two doses of SW vaccine (1125 mIU) (P < 0.001). In the EZ vaccine group, there was no significant difference in antibody level for children vaccinated in the presence of high or low levels of maternal antibodies, whereas there was a marked difference in the SW group. The second EZ vaccine induced a significant antibody increase between 9 months of age (1191 mIU) and 18 months of age (1602 mIU, P=0.011), whereas antibody levels tended to decline from 9 months (1243 mIU) to 18 months of age (998 mIU, P = 0.124) after the second dose of SW vaccine. Conclusively, after two doses of EZ measles vaccine more children were protected at 18 months of age than after two doses of SW. One dose of SW provided the highest antibody response, but a higher proportion of unprotected than one or two doses of EZ. The EZ vaccine was less sensitive to maternal antibodies, and able to increase the antibody response by revaccination, while the second SW vaccine resulted in an unchanged or lower antibody response.

Age Factors↗
PubMed2001

Examining the effects of work externalization through the lens of social identity theory.

This study examines whether dissimilarity among employees that is based on their work status (i.e., whether they are temporary or internal workers) influences their organization-based self-esteem, their trust in and attraction toward their peers, and their altruism. A model that is based on social identity theory posits that work-status dissimilarity negatively influences each outcome variable and that the strength of this relationship varies depending on whether employees have temporary or internal status and the composition of their work groups. Results that are based on a survey of 326 employees (189 internal and 137 temporary) from 34 work groups, belonging to 2 organizations, indicate that work-status dissimilarity has a systematic negative effect only on outcomes related to internal workers when they work in temporary-worker-dominated groups.

Adult↗
PubMed2001

Blue native polyacrylamide gel electrophoresis: a powerful tool in diagnosis of oxidative phosphorylation defects.

Catalytic activity of oxidative phosphorylation complexes is maintained following separation by Blue Native polyacrylamide gel electrophoresis (BN-PAGE). In BN-PAGE gels, using histochemical staining methods, we have demonstrated enzymatic activity of the complexes I, II, IV, and V in heart and skeletal muscle, liver, and cultured skin fibroblasts. The combination of BN-PAGE and catalytic staining can be successfully applied for detection of complex deficiencies. Tissues from 18 patients with deficiency in the oxidative phosphorylation as detected by spectrophotometric assay were used (10 patients complex IV, three patients complex I, one patient complex II, one patient complex I+III, three patients complex I+IV). The gene defect was located in nuclear DNA in five patients and mitochondrial DNA in one patient. In samples from patients with a severe deficiency, almost complete absence of the corresponding enzyme band is observed after catalytic staining in the gel. In patients with known partial deficiency, a milder decrease of the corresponding enzyme band is demonstrated. The amount of protein in complexes I, V, and III can easily be evaluated in samples from heart and skeletal muscle after separation by BN-PAGE using silver or Coomassie staining. The protein amount in complex IV is difficult to visualize by silver staining but easier by the Coomassie technique. In samples from liver and cultured skin fibroblasts, evaluation of protein amount is more difficult due to high background staining. In these tissues, immunoblotting can be done after BN-PAGE and subsequent transfer to a nitrocellulose membrane.

Adolescent↗
PubMed2001

Pre hospital issues in acute myocardial infarction.

OBJECTIVES: Time is of prime importance in the management of acute myocardial infarction (AMI). Time to hospital admission should be minimised for maximum thrombolytic benefit. The present paper has evaluated some socio-demographic factors influencing pre hospital delay. METHODS: This prospective observational study of 1,072 patients with AMI admitted to 14 hospitals in South India was done over one year. Socio-demographic factors viz. time of symptom onset, place of residence, type of transportation to hospital, distance travelled, as well as clinical and treatment details were recorded. Hospitals were grouped based on their location into metropolitan and town hospitals. RESULTS: Males predominated (85%) and had AMI at a younger age than females. Most patients (74%) travelled less than 30 km to a hospital. The mean distance travelled to a town hospital was longer than that to a metropolitan hospital (24.2 km vs 21 km; p < 0.0001); however there was no significant difference in the type of transportation or time taken to reach either of the hospitals. Majority (79%) of patients arrived at a hospital within the thrombolytic window of 12 hours (mean time = 11 hours). The occurrence of a previous MI had no influence on time taken to hospital arrival, questioning the role of symptom education as an interventional strategy to reduce pre hospital delay. Patients older than 70 years and females in towns with symptom onset during the day (6 am to 6 pm) took a longer time to reach hospital. CONCLUSION: Community facilities do not affect pre hospital delay. Interventions should focus on reducing decision time to call for help and the role of symptom education needs further evaluation.

Community Health Services↗
PubMed2000

Food security among preschool children.

A cross-sectional study of preschool children from 450 families from a residential colony of 'D' class hospital employees was undertaken to study food security & associated variables. Food security was established from (a) 24 hours recall method with 1 day weighment and (b) monthly food purchase inventory for cereals and pulses. Relationship between food secure status and variables of interest was studied from Chi-square value and odds ratio. Only 42.6% households and 54% preschool children from these households were calorically secure. Insecurity was the highest in 48-59 months age group. Per capital income, increasing birth order, family size, household size, less years of schooling of the mother, less than 4 meals per day and pulse insufficiency at home were associated with food insecurity. Per capita income ensures food availability at home. Family size and household size probably ensure distribution. Mother's education, frequent feeds more than four, ensure that it reaches the preschool children.

Child, Preschool↗
PubMed2000

The use of liver spheroids as an in vitro model for studying induction of the stress response as a marker of chemical toxicity.

Stress protein induction has been advocated as a sensitive indicator of compound-induced toxicity. In monolayer cultures of primary hepatocytes, however, the two stress proteins, Hsp25 and Hsp72/3 are up-regulated, probably due to the effect of the isolation procedure and adaptation of the cells to the culture conditions. The aim of the current studies was to determine whether liver spheroids would provide an improved experimental model for the study of heat shock protein induction in vitro. Primary rat hepatocytes were cultured as liver spheroids and the expression of Hsp25 and Hsp72/3 measured along with the levels of ATP, GSH and albumin secretion. Hsp72/3 was initially increased in spheroid culture but returned to in vivo levels after 3 days of culture. Hsp25 was maintained at in vivo levels until day 6 of culture, after which levels increased slightly. The effects of the two hepatotoxins, hydrazine and cadmium chloride (CdCl(2)), were therefore measured on day 6 of spheroid culture. CdCl(2) had no effect on Hsp25 but increased Hsp72/3 at concentrations that affected other biochemical parameters. Hydrazine caused a rapid reduction in ATP levels and albumin secretion, but did not affect Hsp72/3. Hsp25 was slightly induced by hydrazine at later sampling times at concentrations, however, that affected other biochemical parameters. It can be concluded that liver spheroids provide a model for studying stress protein expression. However, the increase in stress proteins appears to be a relatively insensitive parameter compared to other more conventionally used toxicity endpoints and the response appears to vary with individual toxins under study.

Adenosine Triphosphate↗
PubMed2000

Non-dipping circadian blood pressure and renal impairment are associated with increased mortality in diabetes mellitus.

AIMS: To assess the relevance of circadian blood pressure variation to future morbidity and mortality in patients with diabetes mellitus. METHODS: A retrospective descriptive 4 year follow-up study of data collected after ambulatory blood pressure monitoring in a clinic setting. RESULTS: Seventy-five patients (46 male; 29 female) of whom 41 % had Type 1 diabetes and 59% Type 2 were followed up for a median of 42 months (11-56). The median creatinine for the whole group at baseline was 101 (56-501) micromol/l. The median circadian blood pressures for the total study population were 147 (110-194)/87 (66-109) mmHg during daytime and 132 (86-190)/77 (50-122) mmHg during night-time. Half of the patients exhibited a fall in night-time pressures to 10% lower than daytime pressures (dippers). Dippers were younger, 47 (32-75) years, than non-dippers, 57 (35-79) years, P = 0.03. Over time, dippers had a lower mortality than non-dippers, with 8% deaths in the cohort of dippers, 26% deaths in the cohort of non-dippers, P = 0.04. Cox regression analysis revealed significant contributions from age, duration of diabetes and baseline renal function to subsequent mortality in non-dippers. Analysing current degree of renal impairment and original dipper status together revealed that, of those patients whose creatinine remained normal, 7% of patients whose blood pressure dipped had subsequently died and 10% of non-dipping patients had died; of those patients whose creatinine unequivocally rose, 10% of dipping patients had died and 42% of non-dipping patients had died, P = 0.03 CONCLUSIONS: Loss of circadian variation in blood pressure is associated with an increased mortality rate, regardless of diabetes type. The combination of non-dipping and subsequent renal impairment leads to the highest mortality rate. The study suggests a role for ambulatory blood pressure monitoring in day-to-day clinical practice to select patients with nephropathy who are at greatest risk, in an effort to alter outcome.

Adult↗
PubMed2000

The difficult airway.

The difficult airway, although rare, still occurs with a frequency sufficient to require that all personnel associated with airway management be familiar with methods to use when confronted with a challenging airway. Methods of airway assessment are helpful but lack adequate sensitivity and specificity. The most effective means of anticipating a difficult airway lies in an integrated approach utilizing the history, physical exam, and the patient's medical record. The most effective manner of dealing with a difficult airway involves proper anticipation, patient preparation, and the development of practical, well thought out contingency plans. Most importantly, extubation must only occur after a plan has been designed to ensure that the patient may be adequately supported in the event of a premature extubation. Certain injuries to the airway and esophagus are more common in patients in whom intubation was difficult. Such patients should be closely watched and informed about the signs and symptoms of tracheal and esophageal injury.

Adult↗