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Biomedical subjects

D Patel

Publications and source records attributed to D Patel.

At least 55 records · Page 3Linked to original sources
PubMed2000

Immunogold evidence that neuronal gap junctions in adult rat brain and spinal cord contain connexin-36 but not connexin-32 or connexin-43.

Physiological and ultrastructural evidence indicates that gap junctions link many classes of neurons in mammalian central nervous system (CNS), allowing direct electrical and metabolic communication. Among at least six gap junction-forming connexin proteins in adult rat brain, connexin- (Cx) 32, Cx36, and Cx43 have been reported to occur in neurons. However, no connexin has been documented at ultrastructurally defined neuronal gap junctions. To address this question directly, freeze-fracture replica immunogold labeling (FRIL) and immunofluorescence (IF) were used to visualize the subcellular and regional localization of Cx36 in rat brain and spinal cord. Three antibodies were generated against different sequences in Cx36. By Western blotting, these antibodies detected protein at 36 and 66 kDa, corresponding to Cx36 monomer and dimer forms, respectively. After double-labeling for Cx36 and Cx43 by FRIL, neuronal gap junctions in inferior olive, spinal cord, and retina were consistently immunogold-labeled for Cx36, but none were labeled for Cx43. Conversely, Cx43 but not Cx36 was detected in astrocyte and ependymocyte gap junctions. In >250 Cx32/Cx43 single- and double-labeled replicas from 10 CNS regions, no neuronal gap junctions were labeled for either Cx32 or Cx43. Instead, Cx32 and Cx43 were restricted to glial gap junctions. By IF, Cx36 labeling was widely distributed in neuropil, including along dendritic processes and within neuronal somata. On the basis of FRIL identification of Cx36 in neuronal gap junctions and IF imaging of Cx36 throughout rat brain and spinal cord, neuronal gap junctions containing Cx36 appear to occur in sufficient density to provide widespread electrical and metabolic coupling in adult CNS.

Animals↗
PubMed2000

An atomic force microscopy investigation of bioadhesive polymer adsorption onto human buccal cells.

Atomic force microscopy (AFM) was used to examine the buccal cell surface in order to image the presence of adsorbed bioadhesive polymers identified from previous work. Isotonic saline solution (5 ml) containing either polycarbophil (pH 7.6), chitosan (pH 4.5) or hydroxypropyl methylcellulose (pH 7.6) (0.5% w/v) was exposed to freshly collected buccal cells (ca. 48x10(4) cells/test) for 15 min at 30 degrees C. The cells were then rinsed with a small volume of double distilled water, allowed to air-dry on a freshy cleaved mica surface and imaged using contact mode AFM. Untreated cells showed relatively smooth surface characteristics, with many small 'crater-like' pits and indentations spread over cell surfaces. Cells that had been treated with all the investigated polymers appeared to have lost the crater and indentation characteristic and gained a higher surface roughness. These results suggest that polymer chains had adsorbed onto the cell surfaces. Quantitative image analysis of cell topography showed significant increases (P<0.05) in arithmetic roughness average (R(a)) for all the investigated polymer treated cells surfaces with respect to untreated control specimens. The changes in surface topography indicate the presence of adsorbed polymer, confirming previous work. This study demonstrates the suitability of AFM as a powerful and sensitive technique for detecting and imaging bioadhesive polymers present on mucosal cell surfaces.

Acrylic Resins↗
PubMed2000

Three-dimensional confinement in the conduction band structure of InP

Strong quantum confinement in InP is observed to significantly reduce the separation between the direct and indirect conduction band states. The effects of three-dimensional confinement are investigated by tailoring the initial separation between conduction band states using quantum dots (QDs) of different sizes and hydrostatic pressure. Analyses of the QD emission spectra show that the X(1c) states are lowest in energy at pressures of approximately 6 GPa, much lower than in the bulk. The transition to the X(1c) states can be explained by either a sequence of gamma-L and L-X crossings, or by the crossover between strongly coupled gamma and X states.

Journal Article↗
PubMed2000

Impact of electrical cable insulating oil on the mineralisation of [1-(14)C]glucose in soil.

Subsurface high voltage electric cables are commonly insulated using dodecylbenzene in combination with mineral oil. This work assessed the impact of increasing concentrations of cable insulating oil (0-10% dry weight) on soil microbial respiration as determined by mineralisation of [1-(14)C]glucose (11 microg C g(-1) soil). Acute impact was assessed from 0 days to 21 days, and chronic impact was assessed after 300 days. This study found that cable insulating oil increased respiratory activity of soil microflora. The extent of impact was found to depend on both oil concentration and the length of oil-soil contact time. Following acute exposure (21-days oil-soil contact time), it was found that oil concentrations up to 1% promoted a significant (P<0.05) increase in the extent of [1-(14)C]glucose mineralisation to (14)CO(2) relative to the control. In contrast, higher concentrations of cable insulating oil (5% and 10%) promoted no significant (P0.05) increase in the extent of [1-(14)C]glucose mineralisation to (14)CO(2) relative to the control. Following chronic exposure (300-days oil-soil contact time), the extent of mineralisation was greater at all oil concentrations applied relative to the control. For oil concentrations up to and including 1%, there was a decrease in the extent of elevation in mineralisation relative to the values after 21-days exposure. At higher oil concentrations, namely 5% and 10%, the extent of elevation in mineralisation was comparable with that after 21-days oil-soil contact time. We suggest that the increase in mineralisation of glucose indicates that cable insulating oil is a readily available carbon source to the carbon-limited soil microflora.

Bacteria↗
PubMed2000

Malignant pleural mesothelioma in a 13-year-old girl.

Pleural mesothelioma is an uncommon tumor in all age groups, but is especially rare in childhood. We describe the clinical and radiological features of malignant pleural mesothelioma in a 13-year-old girl. The chest radiograph showed nearly complete opacification and loss of volume in the left hemithorax. Computed tomography demonstrated a large pleural effusion centrally surrounded by a thick enhancing rind of soft tissue. The radiological features of childhood pleural mesothelioma in our case were similar to those described in adults with this disease.

Child↗
PubMed2000

A comparison of six commercial assays for total and free prostate specific antigen (PSA): the predictive value of the ratio of free to total PSA.

OBJECTIVE: To evaluate the clinical utility of six commercial assays for free prostate specific antigen (fPSA) and the derived ratio of fPSA to total PSA in distinguishing between patients with prostate cancer or benign prostate hyperplasia (BPH). MATERIALS AND METHODS: Each assay was evaluated against a panel of serum samples comprising those from patients with prostatic disease, other malignancies, normal subjects and sera containing substances which might interfere with the immunoassay. RESULTS: The levels of total (tPSA), fPSA and their ratio (f/tPSA) were compared among the different samples. All assays showed similar specificities for prostate carcinoma but differed in the positive predictive values of f/tPSA. CONCLUSIONS: Although all six assays were equimolar, there were differences in calibration, particularly for fPSA. The ability of f/tPSA to discriminate between benign and malignant prostatic disease depended on the assay used. The f/tPSA is not valid when the tPSA and fPSA assays are obtained from different manufacturers.

Calibration↗
PubMed2000

Role of preoperative antibiotic prophylaxis in preventing postoperative peritonitis in newly placed peritoneal dialysis catheters.

The role of vancomycin and other antibiotics in the treatment of acute peritonitis in peritoneal dialysis (PD) patients is well established. However, the role of preoperative vancomycin or cephalosporins in preventing early infection in newly placed PD catheters remains controversial. We performed a prospective randomized study to examine the role of vancomycin or cefazolin prophylaxis in decreasing the incidence of postoperative peritonitis. Over a 6-year period, 221 patients undergoing 254 permanent peritoneal catheter placement procedures were randomized into three groups. Group I patients (86 procedures) were administered a single intravenous (IV) dose of vancomycin, 1,000 mg, 12 hours before peritoneal catheter placement procedures, whereas group II patients (85 procedures) were administered a single IV dose of cefazolin, 1,000 mg, 3 hours before the procedure. Group III patients (83 procedures) were not administered antibiotics preoperatively for at least 1 week before the procedure. Patients were monitored for peritonitis in the following 14 days. Peritonitis developed in 1 patient (1%) in group I (vancomycin group) and 6 patients (7%) in group II (cefazolin group) compared with 10 patients (12%) in group III (control group); P = 0.02. We conclude that the use of preoperative single-dose IV vancomycin prophylaxis for permanent PD catheter placement reduces the risk for postoperative peritonitis. Single-dose vancomycin is superior to single-dose cefazolin in reducing the risk for postoperative peritonitis. Absence of prophylaxis is associated with a high risk for developing postoperative peritonitis.

Adolescent↗
PubMed2000

Impaired sarcoplasmic calcium release inhibits myocardial contraction in experimental sepsis.

PURPOSE: In septic shock, myocardial dysfunction develops over the course of illness, but the mechanism of this depression is not clear. In this study, mechanisms of myocardial dysfunction were examined in a porcine model of Escherichia coli sepsis. MATERIALS AND METHODS: Animals were subjected to 4 hours of bacteria infusion (n = 5) (septic group) or saline infusion (n = 5) (nonseptic group), after which trabeculae were removed from the right ventricle and placed into a recirculating water bath. Measurements of steady-state contraction (SSC) were obtained at 0.5, 1, and 2 Hz. Indirect indices were used to assess abnormalities in myocardial calcium metabolism in sepsis. Extrasystoles (ES) were used to assess transsarcolemmal (TSL) calcium flux and were measured at 300 milliseconds, 400 milliseconds, and 500 milliseconds after the preceding stimulus. Postrest contraction (PRC) is an indicator of SR recirculation from the uptake to the release site and was obtained after interposing intervals of rest between steady-state beats at 0.5 Hz. Rapid-cooling contracture (RCC) is an indicator of sarcoplasmic reticulum (SR) content and was obtained at 0.5, 1, and 2 Hz and after interposing intervals of rest at 0.5 Hz. RESULTS: SSC was not different between groups at 0.5 Hz, but compared with the nonseptic group, SSC decreased at 1 and 2 Hz in the septic group (P < .05). PRC and TSL were not different between groups. During rest intervals, calcium leaks out of SR through the ryanodine channel (ie, SR calcium release channel). In the septic group, as assessed by RCC, SR calcium leak was less than that found in the nonseptic group. CONCLUSION: These results indicate that myocardial dysfunction in sepsis is frequency dependent, and that the mechanism is most likely caused by inhibition of SR calcium release owing to blockade of the ryanodine channel.

Analysis of Variance↗
PubMed2000

Methicillin-resistant Staphylococcus aureus and multidrug resistant tuberculosis: Part 1.

The first of these articles reviews the epidemiology of MRSA and its clinical importance in a healthcare setting. The methods of controlling the spread of hospital acquired MRSA are discussed with an emphasis on the role of screening staff for MRSA. Relevant papers for the review were identified by a systematic literature search on Medline. The prevalence of MRSA is increasing in the United Kingdom, as is the prevalence of 'epidemic' MRSA strains. Several countries have recently reported cases of Staphylococcus aureus with intermediate-level resistance to vancomycin. The key measures to minimizing hospital-acquired MRSA are stringent infection control programmes and strict antibiotic policies. Staff screening should only be undertaken after a detailed risk assessment of the local situation has been made by the occupational health and infection control teams. Priority should be given to high-risk areas of a hospital where MRSA is endemic.

Drug Resistance, Multiple↗
PubMed2000

Methicillin-resistant Staphylococcus aureus and multidrug resistant tuberculosis: Part 2.

Drug resistant tuberculosis has been recognized since chemotherapy first became available. However, drug resistance has increased in many countries, and recently strains resistant to both rifampicin and isoniazid (multidrug resistant tuberculosis) have emerged. This review discusses the epidemiology of multidrug resistant tuberculosis (MDRTB), and the control of MDRTB in healthcare facilities. Relevant papers for this review were identified by a systematic literature search on Medline. MDRTB is already established world-wide, and although the overall problem of resistance remains low in the UK, it is of significant clinical importance due to its high case-fatality, higher transmission risk, and complex treatment. The key elements of MDRTB control are prompt recognition, confirmation and treatment of cases, and the institution of strict infection control procedures to reduce the airborne spread of infection from infectious patients to others. This review emphasizes the importance of a multidisciplinary approach to management, with liaison between tuberculosis physicians, the microbiology department, infection control team, consultant in communicable disease, and occupational health.

Antibiotics, Antitubercular↗
PubMed2000

Methylene as a possible universal footprinting reagent that will include hydrophobic surface areas: overview and feasibility: properties of diazirine as a precursor.

Methylene is one of, if not the, most reactive organic chemical known. It has a very low specificity, which makes it essentially useless for synthesis, but suggests a possible role in protein footprinting with special importance in labeling solvent accessible nonpolar areas, identifying ligand binding sites, and outlining interaction areas on protomers that form homo or hetero oligomers in cellular assemblies. The singlet species is easily and conveniently formed by photolysis of diazirine. The reactions of interest are insertion into C-H bonds and addition to multiple bonds, both forming strong covalent bonds and stable compounds. Reaction with proteins and peptides is reported even in aqueous solutions where the vast majority of the reagent is used up in forming methanol. Species containing up to 5 to 10 extra :CH2 groups are easily detected by electrospray mass spectroscopy. In a mixture of a 14 Kd protein and a noninteracting 1.7 Kd peptide, the distribution of mass peaks in the electrospray spectra was close to that expected from random modification of the estimated solvent accessible area for the two molecules. For analysis at the single residue level, quantitation at labeling levels of one 13CH2 group per 10 to 20 kDa of protein appears to be possible with isotope ratio mass spectroscopy. In the absence of reactive solvents, photolysis of diazirine produces oily polymeric species that contain one or two nitrogen atoms, but not more, and are water soluble.

Animals↗
PubMed2000

Risk factors and opportunities for prevention of early-onset neonatal sepsis: a multicenter case-control study.

BACKGROUND: Early-onset group B streptococcal (GBS) prevention efforts are based on targeted use of intrapartum antibiotic prophylaxis (IAP); applicability of these prevention efforts to infections caused by other organisms is not clear. METHODS: Multicenter surveillance during 1995 to 1996 for culture-confirmed, early-onset sepsis in an aggregate of 52 406 births; matched case-control study of risk factors for GBS and other sepsis. RESULTS: Early-onset disease occurred in 188 infants (3.5 cases per 1000 live births). GBS (1.4 cases per 1000 births) and Escherichia coli (0.6 cases per 1000 births) caused most infections. GBS sepsis less often occurred in preterm deliveries compared with other sepsis. Compared with gestation-matched controls without documented sepsis, GBS disease was associated with intrapartum fever (matched OR, 4.1; CI, 1.2-13.4) and frequent vaginal exams (matched OR, 2.9; CI, 1.1-8. 0). An obstetric risk factor-preterm delivery, intrapartum fever, or membrane rupture >/=18 hours-was found in 49% of GBS cases and 79% of other sepsis. IAP had an adjusted efficacy of 68.2% against any early-onset sepsis. Ampicillin resistance was evident in 69% of E coli infections. No deaths occurred among susceptible E coli infections, whereas 41% of ampicillin-resistant E coli infections were fatal. Ninety-one percent of infants who developed ampicillin-resistant E coli infections were preterm, and 59% of these infants were born to mothers who had received IAP. CONCLUSIONS: Either prenatal GBS screening or a risk-based strategy could potentially prevent a substantial portion of GBS cases. Sepsis caused by other organisms is more often a disease of prematurity. IAP seemed efficacious against early-onset sepsis. However, the severity of ampicillin-resistant E coli sepsis and its occurrence after maternal antibiotics suggest caution regarding use of ampicillin instead of penicillin for GBS prophylaxis.

Ampicillin Resistance↗
PubMed2000

Calcaneal bone mineral density and mechanical strength of the metatarsals.

The primary aim of this study was to determine the predictive value of the bone mineral density of the calcaneus for fracture of the metatarsals. The authors report a strong positive correlation between the bone mineral density of the calcaneus and the four-point bending strength of each of the five metatarsals (r2 = 0.76, 0.64, 0.70, 0.68, and 0.78 for metatarsals 1 through 5, respectively). In addition, the relative strengths of the metatarsals and the correlation with their in vivo loads during gait as previously reported in the literature are discussed.

Absorptiometry, Photon↗
PubMed2000

Preoperative vancomycin prophylaxis for newly placed peritoneal dialysis catheters prevents postoperative peritonitis.

The role of vancomycin and other antibiotics in treatment of acute peritonitis in peritoneal dialysis patients is well established. However, the role of preoperative vancomycin or cephalosporins in preventing early infection in newly placed peritoneal dialysis catheters remains controversial. We performed a prospective randomized study to examine the role of vancomycin or cefazolin prophylaxis in decreasing the incidence of postoperative peritonitis. Over 8-year period, 265 patients undergoing 305 permanent peritoneal catheter placement procedures were randomized into three groups. Group I (103 procedures) received a single intravenous (i.v.) dose of 1000 mg vancomycin 12 hours before the peritoneal catheter placement procedure. Group II (102 procedures) received a single i.v. dose of 1000 mg of Ancef (cefazolin) 3 hours before the procedure. Group III (100 procedures) received no antibiotics preoperatively for a least one week before the procedure. Patients were monitored for peritonitis during the following 14 days. Peritonitis developed in 1 patient (1%) in Group I (vancomycin group) compared to 12 patients (12%) in Group III (control group), p = 0.002, and in 9 patients (9%) in Group II (cefazolin group) compared to Group III, p = 0.68. We conclude that the use of preoperative single-dose i.v. vancomycin prophylaxis for permanent peritoneal dialysis catheter placement reduces the risk of postoperative peritonitis. Cefazolin did not achieve a statistically significant difference from the control group and may not provide adequate prophylaxis.

Adolescent↗
PubMed2000

In vivo protection of dna damage associated apoptotic and necrotic cell deaths during acetaminophen-induced nephrotoxicity, amiodarone-induced lung toxicity and doxorubicin-induced cardiotoxicity by a novel IH636 grape seed proanthocyanidin extract.

Grape seed extract, primarily a mixture of proanthocyanidins, has been shown to modulate a wide-range of biological, pharmacological and toxicological effects which are mainly cytoprotective. This study assessed the ability of IH636 grape seed proanthocyanidin extract (GSPE) to prevent acetaminophen (AAP)-induced nephrotoxicity, amiodarone (AMI)-induced lung toxicity, and doxorubicin (DOX)-induced cardiotoxicity in mice. Experimental design consisted of four groups: control (vehicle alone), GSPE alone, drug alone and GSPE+drug. For the cytoprotection study, animals were orally gavaged 100 mg/Kg GSPE for 7-10 days followed by i.p. injections of organ specific three drugs (AAP: 500 mg/Kg for 24 h; AMI: 50 mg/Kg/day for four days; DOX: 20 mg/Kg for 48 h). Parameters of study included analysis of serum chemistry (ALT, BUN and CPK), and orderly fragmentation of genomic DNA (both endonuclease-dependent and independent) in addition to microscopic evaluation of damage and/or protection in corresponding PAS stained tissues. Results indicate that GSPE preexposure prior to AAP, AMI and DOX, provided near complete protection in terms of serum chemistry changes (ALT, BUN and CPK), and significantly reduced DNA fragmentation. Histopathological examination of kidney, heart and lung sections revealed moderate to massive tissue damage with a variety of morphological aberrations by all the three drugs in the absence of GSPE preexposure than in its presence. GSPE+drug exposed tissues exhibited minor residual damage or near total recovery. Additionally, histopathological alterations mirrored both serum chemistry changes and the pattern of DNA fragmentation. Interestingly, all the drugs, such as, AAP, AMI and DOX induced apoptotic death in addition to necrosis in the respective organs which was very effectively blocked by GSPE. Since AAP, AMI and DOX undergo biotransformation and are known to produce damaging radicals in vivo, the protection by GSPE may be linked to both inhibition of metabolism and/or detoxification of cytotoxic radicals. In addition, its' presumed contribution to DNA repair may be another important attribute, which played a role in the chemoprevention process. Additionally, this may have been the first report on AMI-induced apoptotic death in the lung tissue. Taken together, these events undoubtedly establish GSPE's abundant bioavailability, and the power to defend multiple target organs from toxic assaults induced by structurally diverse and functionally different entities in vivo.

Acetaminophen↗
PubMed1999

The E6 protein of human papillomavirus type 16 binds to and inhibits co-activation by CBP and p300.

The co-activators CBP and p300 are important for normal cell differentiation and cell cycle progression and are the targets for viral proteins that dysregulate these cellular processes. We show here that the E6 protein from the oncogenic human papillomavirus type 16 (HPV-16) binds to three regions (C/H1, C/H3 and the C-terminus) of both CBP and p300. The interaction of E6 with CBP/p300 was direct and independent of proteins known to bind the co-activators, such as p53. The E6 protein from low-risk HPV type 6 did not interact with C/H3 or the C-terminus but associated with the C/H1 domain at 50% of the level of HPV-16. HPV-16 E6 inhibited the intrinsic transcriptional activity of CBP/p300 and decreased the ability of p300 to activate p53- and NF-kappaB-responsive promoter elements. Interestingly, some mutations in HPV-16 E6 abrogated C/H3-E6 interactions, but did not alter the ability of E6 to associate with the C/H1 domain, suggesting that these modified proteins could be used to delineate the functional significance of the C/H1 and C/H3 domains of CBP/p300.

Animals↗