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Biomedical subjects

H Patel

Publications and source records attributed to H Patel.

At least 37 records · Page 2Linked to original sources
PubMed2001

Measuring the water retention capacities (MRC) of different microcrystalline cellulose grades.

The ability of various types of microcrystalline cellulose (MCC) to hold water when subjected to an applied force has been assessed by a centrifuge technique. By considering the final percent of water retained after a standard centrifugation, as a function of the initial water content, a moisture retention capacity (MRC) can be determined. Statistical analysis of the results identified that it was possible to divide the nine samples of MCC into six sub-sets in terms of final moisture content retained. Those types which contained added polymer had by far the highest water level remaining. In terms of the MRC value, statistical analysis again sub-divided the celluloses into six sub-sets, although different from those for the final water content. Again those types containing added polymer gave much higher MRC values. As experiments were carried out with initial water/MCC ratios of different levels, statistical analysis of the influence of initial water content on the MRC values was undertaken with each type of MCC. The results showed a varying dependence on initial water level with the different types of cellulose. To provide a value of MRC which characterised the cellulose, the maximum value of MRC at the lowest initial water level was identified. Samples of MCC with low values of MRC have been shown previously to require less water for processing by extrusion/spheronization, while celluloses with a high MRC value appear better for the limitation of water movement during the process of extrusion/spheronization. The water retention must, however, also be considered in association with the rheological properties of the wet powder mass. Thus, while the Avicel RC591 had the highest MRC value, its rheological properties are so that the production of pellets with such a type can be less effective than with other types of MCC.

Algorithms↗
PubMed2001

Impact of PACS on the education of radiology residents: the residents' perspective.

RATIONALE AND OBJECTIVES: Because digital imaging and the picture archiving and communication system (PACS) are replacing radiographic film, the effect of PACS on residents' perceptions and their educational experience was investigated. MATERIALS AND METHODS: Residents taking part in large diagnostic radiology training programs at two hospitals were surveyed. Approximately 75% of radiographic studies were reviewed with the use of PACS at both hospitals. Survey topics included technical and didactic issues based on direct and indirect comparison with analog (conventional film) images. RESULTS: Fifty residents were polled (20 respondents). The majority has been using PACS for more than 1 year (14 of 20, 70%) to interpret 75%-100% of cases (11 of 20, 55%). The majority believed that PACS improved patient care (15 of 20, 75%) and their educational experience (15 of 20, 75%). A minority believed that increased patient throughput was harmful to the educational experience (five of 20, 25%) because it permitted attending radiologists to review cases too quickly (four of 20, 20%). Residents favored PACS over hard-copy images for ease of manipulation, resolution, and ability to see pathologic conditions and normal anatomic characteristics. CONCLUSION: Residents believe that PACS has positively affected their learning experience and does not negatively affect the quality of resident education.

Attitude of Health Personnel↗
PubMed2001

Detection and clinical significance of occult tumour cells in colorectal cancer.

BACKGROUND: A variety of techniques have been employed for the detection of occult tumour cells in the blood, bone marrow and lymph nodes of patients with colorectal cancer. This review examines the methods used, results obtained and the clinical significance of studies in this field. METHODS: A Medline literature search was performed using the terms colorectal cancer, minimal residual disease, micrometastasis, polymerase chain reaction, reverse transcriptase polymerase chain reaction and immunocytochemistry; further references were obtained from key articles. RESULTS: Immunocytochemical examination of bone marrow is the benchmark for detecting clinically significant occult disease. Larger standardized studies are required to confirm the prognostic significance of molecular assays for the detection of tumour cells in blood and bone marrow. The prognostic significance of lymph node tumour cells detected by either immunohistochemical or molecular methods awaits further affirmation. CONCLUSION: Standardization of terminology and techniques used, combined with large prospective clinical studies, is required if detection of occult residual disease is to become a prognostic marker for recurrence in colorectal cancer.

Biomarkers, Tumor↗
PubMed2001

Homozygosity at chromosome 8qter in individuals affected by mal de Meleda (Meleda disease) originating from the island of Meleda.

BACKGROUND: The inherited palmoplantar keratodermas (PPKs) are a clinically heterogeneous group of disorders characterized by thickening of the skin of the palms and the soles. These diseases also exhibit genetic heterogeneity and many autosomal dominant and recessive forms have been described. Mal de Meleda (Meleda disease, MD) is an autosomal recessive form of PPK first described on the Dalmatian island of Meleda. A gene for MD has recently been assigned to the most telomeric portion of chromosome 8q using two large Algerian families. OBJECTIVES: To determine whether the same gene underlies the skin disease in Meleda islanders. METHODS: We have examined five affected individuals originating from the Dalmatian island itself for 8qter homozygosity. RESULTS: This region was found to be homozygous in all five affected individuals but in none of the 20 other unaffected family members examined. CONCLUSIONS: The current study confirms the localization of a gene for MD to 8qter using samples from the island of Meleda, highlighting the clinical and genetic homogeneity of this condition.

Chromosomes, Human, Pair 8↗
PubMed2001

Penoplasty for buried penis in children: report of 50 cases.

PURPOSE: The authors report their experience with a large number of children with buried penis and describe their surgical technique. METHODS: Fifty consecutive cases of buried penis that occurred between 1993 and 1999 were analyzed by chart review. Age at the time of surgery was 11 months to 13 years. Each patient underwent elective surgical repair utilizing a surgical technique not described previously. The authors' technique avoids a circumferential incision at the base of the penis, decreasing postoperative edema. The authors also utilize a unique through and through vertical mattress suture at the base of the penis that firmly attaches the shaft skin to the underlying corpora. RESULTS: All patients had a good to excellent outcome with a low postoperative complication rate. One patient fell during the postoperative period and developed a wound dehiscence. Early in the series 3 patients underwent additional procedures for recurrent retraction (6%). All patients experienced some postoperative discomfort as expected. Edema, when present, was mild and resolved within an acceptable period of time. All patients had a good cosmetic result with increased visualization of the penile shaft. CONCLUSIONS: A surgical approach to the buried penis is warranted in most circumstances. There are psychological benefits to both the patients and the parents. Although the authors perform the procedure as early as 11 months, it can be performed safely at 3 months. The procedure reported here provides immediate excellent cosmetic results with a low complication rate. The authors do not recommend suprapubic lipectomy either alone or in combination with the buried penis procedure. Circumcision should be avoided in an infant with a definite diagnosis of buried penis.

Adolescent↗
PubMed2001

Female circumcision.

Female circumcision, more accurately known as female genital mutilation, is still a common practice in parts of Africa. This ritual genital operation can involve partial or complete excision of the clitoris and labia minora as well as infibulation (labial fusion). The case reported here involves a 16-year-old African girl with a complication of this mutilating procedure.

Adolescent↗
PubMed2001

Bifrontal decompressive craniectomy in the management of posttraumatic intracranial hypertension.

Bifrontal decompressive craniectomy has been used on an ad hoc basis for the treatment of post-traumatic intracranial hypertension for more than thirty years. In this observational study we report the clinical outcome and physiological effects of the procedure in a series of 26 patients with refractory intracranial hypertension treated on a protocol driven basis. Bifrontal decompressive craniectomy was associated with significant reductions in mean ICP from 37.5 to 18.1 mmHg (p = 0.003). In addition, craniectomy reduced the amplitude of ICP waves (p < 0.02) and increased compensatory reserve (p < 0.05). A favourable outcome was achieved in 69% of patients; 8% were severely disabled and 23% died. We conclude that this study provides pathophysiological evidence that bifrontal decompressive craniectomy significantly reduces posttraumatic intracranial hypertension and improves pressure dynamics. Our results support the continued use of bifrontal decompressive craniectomy in selected patients after head injury.

Adolescent↗
PubMed2001

Self antigen prognostic for human immunodeficiency virus disease progression.

We have recently found that an extracellular protein, alpha(1) proteinase inhibitor (alpha(1)PI; alpha(1) antitrypsin), is required for in vitro human immunodeficiency virus (HIV) infectivity outcome. We show here in a study of HIV-seropositive patients that decreased viral load is significantly correlated with decreased circulating alpha(1)PI. In the asymptomatic category of HIV disease, 100% of patients manifest deficient levels of active alpha(1)PI, a condition known to lead to degenerative lung diseases and a dramatically reduced life span. Further, HIV-associated alpha(1)PI deficiency is correlated with circulating anti-alpha(1)PI immunoglobulin G. These results suggest that preventing HIV-associated alpha(1)PI deficiency may provide a strategic target for preventing HIV-associated pathophysiology.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Tumor-related epilepsy in children.

A 10-year retrospective review of 15 children with cerebral tumors and seizures was conducted to study the factors responsible for delay in the diagnosis of tumors and to assess outcome following surgery. Mean duration of seizures prior to surgery was 37 months. Ninety-three percent had no focal neurologic deficits. Head computed tomography was abnormal in 64%, whereas magnetic resonance imaging was abnormal in all patients. Electroencephalography showed focal abnormalities ipsilateral to the tumor in 73%. There was no surgical mortality. Eighty percent were seizure free or had rare seizures following surgery. Factors contributing to a delayed diagnosis of the brain tumor included a nonfocal neurologic examination and delay in obtaining an appropriate neuroimaging study. We believe that head magnetic resonance imaging should be the investigation of choice in partial epilepsies.

Adolescent↗
PubMed2001

Three arginine residues in apolipoprotein A-I are critical for activation of lecithin:cholesterol acyltransferase.

Previous studies have suggested that the helical repeat formed by residues 143;-164 of apolipoprotein A-I (apoA-I) contributes to lecithin:cholesterol acyltransferase (LCAT) activation. To identify specific polar residues involved in this process, we examined residue conservation and topology of apoA-I from all known species. We observed that the hydrophobic/hydrophilic interface of helix 143;-164 contains a cluster of three strictly conserved arginine residues (R149, R153, and R160), and that these residues create the only significant positive electrostatic potential around apoA-I. To test the importance of R149, R153, and R160 in LCAT activation, we generated a series of mutant proteins. These had fluorescence emission, secondary structure, and lipid-binding properties comparable to those of wild-type apoA-I. Mutation of conserved residues R149, R153, and R160 drastically decreased LCAT activity on lipid-protein complexes, whereas control mutations (E146Q, D150N, D157N, R171Q, and A175R) did not decrease LCAT activity by more than 55%. The markedly decreased activities of mutants R149, R153, and R160 resulted from a decrease in the maximal reaction velocity V(max) because the apparent Michaelis-Menten constant K(m) values were similar for the mutant and wild-type apoA-I proteins. These data suggest that R149, R153, and R160 participate in apoA-I-mediated activation of LCAT, and support the "belt" model for discoidal rHDL. In this model, residues R149, R153, and R160 do not form salt bridges with the antiparallel apoA-I monomer, but instead are pointing toward the surface of the disc, enabling interactions with LCAT. - Roosbeek, S., B. Vanloo, N. Duverger, H. Caster, J. Breyne, I. De Beun, H. Patel, J. Vandekerckhove, C. Shoulders, M. Rosseneu, and F. Peelman. Three arginine residues in apolipoportein A-I are critical for activation of lecithin:cholesterol acyltransferase J. Lipid Res. 2001. 42: 31;-40.

Amino Acid Sequence↗
PubMed2001

Office management of minor wounds.

OBJECTIVE: To review office interventions for minor wounds not requiring sutures, such as abrasions, bites, and lacerations. QUALITY OF EVIDENCE: Most information on minor wound management comes from descriptive studies. Few comparative studies examine the effectiveness of topical antisepsis for minor wounds. Several clinical trials have demonstrated that tissue adhesives produce short- and long-term cosmetic results equivalent to those achieved with suture materials. MAIN MESSAGE: Sterile saline is the least toxic solution for wound irrigation. Chlorhexidine (2%) and povidone iodine (10%) have been the most investigated antiseptic solutions. Systemic antibiotics are unnecessary for wounds unlikely to be infected. All bite wounds require special attention. Primary closure of bite wounds is indicated in certain circumstances: less than 12-hour-old nonpuncture wounds, uninfected wounds, and low-risk lesions (such as on the face). In spite of their many advantages, skin tapes should be used for low-tension wounds only. The popularity of tissue adhesives has greatly increased. Since the advent of newer products (with increased bonding strength and flexibility), adhesives are used to manage most lacerations except those in areas of high tension (e.g., joints) and on mucosal surfaces. CONCLUSION: Minor wounds not requiring sutures can be managed easily in the office.

Anti-Bacterial Agents↗
PubMed2001

A cost-effectiveness model of alternative statins to achieve target LDL-cholesterol levels.

An economic model was developed to estimate the relative cost-effectiveness of alternative HMG-CoA reductase inhibitors (statins)--atorvastatin, cerivastatin, fluvastatin, pravastatin and simvastatin--to achieve target low-density lipoprotein cholesterol (LDL-C) levels in a population of secondary CHD prevention patients. By using a cholesterol target as the endpoint of interest and a dose titration approach, the model assumes that the statins demonstrate a class effect through cholesterol lowering. The model was used to estimate the proportion of patients achieving target LDL-C levels (< 3 mmol/l) under each scenario tested. Total costs and incremental cost-effectiveness relative to no treatment and to the lowest cost option were estimated for each scenario. Total costs were highest for pravastatin and lowest for cerivastatin. Compared with no treatment, the incremental cost per patient treated to target LDL-C varied between 383 Pounds (atorvastatin) and 1213 Pounds (pravastatin). Incremental cost-effectiveness ratios in comparison with the lowest cost treatment (cerivastatin) were 141 Pounds per additional patient achieving target LDL-C with atorvastatin, and 275 Pounds with simvastatin. Fluvastatin and pravastatin were both less effective and more expensive than the lowest cost therapy. Although cerivastatin was associated with lowest expected costs, therapy with atorvastatin achieved the lowest cost-effectiveness ratios. Hence atorvastatin would allow the largest number of patients to be treated to target LDL-C within a fixed drug budget. Choosing between drug therapies on the basis of price alone may be misleading if the effectiveness of therapies varies.

Atorvastatin↗
PubMed2000

A temperature-sensitive adenylyl cyclase mutant of Dictyostelium.

Dictyostelium development starts with the chemotactic aggregation of up to 10(6) amoebae in response to propagating cAMP waves. cAMP is produced by the aggregation stage adenylyl cyclase (ACA) and cells lacking ACA (aca null) cannot aggregate. Temperature-sensitive mutants of ACA were selected from a population of aca null cells transformed with a library of ACA genes, a major segment of which had been amplified by error-prone PCR. One mutant (tsaca2) that can complement the aggregation null phenotype of aca null cells at 22 degrees C but not at 28 degrees C was characterized in detail. The basal catalytic activity of the enzyme in this mutant was rapidly and reversibly inactivated at 28 degrees C. Using this mutant strain we show that cell movement in aggregates and mounds is organized by propagating waves of cAMP. Synergy experiments between wild-type and tsaca2 cells, shifted to the restrictive temperature at various stages of development, showed that ACA plays an important role in the control of cell sorting and tip formation.

Adenylyl Cyclases↗
PubMed2000

Locking regulatory myosin in the off-state with trifluoperazine.

Scallop striated adductor muscle myosin is a regulatory myosin, its activity being controlled directly through calcium binding. Here, we show that millimolar concentrations of trifluoperazine were effective at removal of all regulatory light chains from scallop myosin or myofibrils. More important, 200 microM trifluoperazine, a concentration 10-fold less than that required for light-chain removal, resulted in the reversible elimination of actin-activated and intrinsic ATPase activities. Unlike desensitization induced by metal ion chelation, which leads to an elevation of activity in the absence of calcium concurrent with regulatory light-chain removal, trifluoperazine caused a decline in actin-activated MgATPase activity both in the presence and absence of calcium. Procedures were equally effective with respect to scallop myosin, myofibrils, subfragment-1, or desensitized myofibrils. Increased alpha-helicity could be induced in the isolated essential light chain through addition of 100-200 microM trifluoperazine. We propose that micromolar concentrations of trifluoperazine disrupt regulation by binding to a single high-affinity site located in the C-terminal domain of the essential light chain, which locks scallop myosin in a conformation resembling the off-state. At millimolar trifluoperazine concentrations, additional binding sites on both light chains would be filled, leading to regulatory light-chain displacement.

Adenosine Triphosphatases↗
PubMed2000

Thioredoxin 2 is involved in the oxidative stress response in Escherichia coli.

Two genes encoding thioredoxin are found on the Escherichia coli genome. Both of them are capable of reducing protein disulfide bonds in vivo and in vitro. The catalytic site contains a Cys-X(1)-X(2)-Cys motif in a so-called thioredoxin fold. Thioredoxin 2 has two additional pairs of cysteines in a non-conserved N-terminal domain. This domain does not appear to be important for the function of thioredoxin 2 in donating electrons to ribonucleotide reductase, 3'-phosphoadenylsulfate-reductase, or the periplasmic disulfide isomerase DsbC. Our results suggests that the two thioredoxins are equivalent for most of the in vivo functions that were tested. On the other hand, transcriptional regulation is different. The expression of trxC is regulated by the transcriptional activator OxyR in response to oxidative stress. Oxidized OxyR binds directly to the trxC promoter and induces its expression in response to elevated hydrogen peroxide levels or the disruption of one or several of the cytoplasmic redox pathways. Mutants lacking thioredoxins 1 and 2 are more resistant to high levels of hydrogen peroxide, whereas they are more sensitive to diamide, a disulfide bond-inducing agent.

Base Sequence↗