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S Patel

Publications and source records attributed to S Patel.

At least 325 records · Page 18Linked to original sources
PubMed1998

A novel lysosome-associated membrane glycoprotein, DC-LAMP, induced upon DC maturation, is transiently expressed in MHC class II compartment.

We have identified a novel lysosome-associated membrane glycoprotein localized on chromosome 3q26.3-q27, DC-LAMP, which is homologous to CD68. DC-LAMP mRNA is present only in lymphoid organs and DC. A specific MAb detects the protein exclusively in interdigitating dendritic cells. Expression of DC-LAMP increases progressively during in vitro DC differentiation, but sharply upon activation with LPS, TNFalpha, or CD40L. Confocal microscopy confirmed the lysosomal distribution of the protein. Furthermore, DC-LAMP was found in the MHC class II compartment immediately before the translocation of MHC class II molecules to the cell surface, after which it concentrates into perinuclear lysosomes. This suggests that DC-LAMP might change the lysosome function after the transfer of peptide-MHC class II molecules to the surface of DC.

Amino Acid Sequence↗
PubMed1998

Consideration of conformational transitions and racemization during process development of recombinant glucagon-like peptide-1.

Physicochemical characterization of dry, excipient-free recombinant glucagon-like peptide-1 (rGLP-1) indicates the conformation and purity of the bulk peptide is dependent on the purification scheme and the in-process storage and handling. The recombinant peptide preparations were highly pure and consistent with the expected primary structure and bioactivity. However, variations in solubility were observed for preparations processed by different methods. The differences in solubility were shown to be due to conformational differences induced during purification. A processing scheme was identified to produce rGLP-1 in its native, soluble form, which exhibits FT-IR spectra, consistent with glucagon-like peptide-1 synthesized by solid-state peptide synthesis. rGLP-1 was also found to undergo base-catalyzed amino acid racemization. Racemization can impact the yield and impurity profile of bulk rGLP-1, since the peptide is exposed to alkali during its purification. A combination of enzymatic digestion using leucine aminopeptidase (which cleaves N-terminal L-amino acids >> D-amino acids) and matrix-assisted laser desorption ionization mass spectrometry was used to identify racemization as a degradation pathway. The racemization rate increased with increasing temperature and base concentration, but decreased with increasing peptide concentration. The racemized peptides were shown to be less bioactive than rGLP-1.

Chemical Precipitation↗
PubMed1998

Patenting computer-designed peptides.

The problem of designing new peptides that possess specific properties, such as bactericidal activity, is of wide interest. Recently, attention has focused on the use of Computer-Aided Molecular Design techniques in parallel with more traditional 'synthesise and test' methods. These techniques may typically use Genetic Algorithms to optimise molecules based on Neural Network models that predict activity. In this paper we describe a successful application of this Molecular Design methodology that has resulted in novel bactericidal peptides of real value. A key issue for commercial utilisation of such results is the ability to protect the intellectual property rights associated with the discovery of new molecules. Typically peptide patents use structural templates of amino acid hydrophobicity-hydrophilicity that define highly regular peptide patent spaces. In an extension of established patenting practice we describe a patent application that uses a Neural Net predictive model to define the regions of peptide space that we claim within the patent. This formalism makes no a priori assumptions about the regularity of the patent space. A preliminary comparative investigation of the shape and size of this and other bactericidal peptide patent spaces is conducted.

Algorithms↗
PubMed1998

A regulatory cascade involving AarG, a putative sensor kinase, controls the expression of the 2'-N-acetyltransferase and an intrinsic multiple antibiotic resistance (Mar) response in Providencia stuartii.

A recessive mutation, aarG1, has been identified that resulted in an 18-fold increase in the expression of beta-galactosidase from an aac(2')-lacZ fusion. Transcriptional fusions and Northern blot analysis demonstrated that the aarG1 allele also resulted in a large increase in the expression of aarP, a gene encoding a transcriptional activator of aac(2')-Ia. The effects of aarG1 on aac(2')-Ia expression were mediated by aarP-dependent and -independent mechanisms. The aarG1 allele also resulted in a multiple antibiotic resistance (Mar) phenotype, which included increased chloramphenicol, tetracycline and fluoroquinolone resistance. This Mar phenotype also resulted from aarP-dependent and -independent mechanisms. Sequence analysis of the aarG locus revealed the presence of two open reading frames, designated aarR and aarG, organized in tandem. The putative AarR protein displayed 75% amino acid identity to the response regulator PhoP, and the AarG protein displayed 57% amino acid identity to the sensor kinase PhoQ. The aarG1 mutation, a C to T substitution, resulted in a threonine to isoleucine substitution at position 279 (T279I) in the putative sensor kinase. The AarG product was functionally similar to PhoQ, as it was able to restore wild-type levels of maganin resistance to a Salmonella typhimurium phoQ mutant. However, expression of the aarP and aac(2')-Ia genes was not significantly affected by the levels of Mg2+ or Ca2+, suggesting that aarG senses a signal other than divalent cations.

Acetyltransferases↗
PubMed1998

Multiple coupling of human D5 dopamine receptors to guanine nucleotide binding proteins Gs and Gz.

We have demonstrated previously that D1 dopamine receptors are coupled to both Gs alpha and Go alpha. We examine here the coupling between human D5 dopamine receptors and G proteins in transfected rat pituitary GH4C1 cells. Similar to D1 receptors, cholera toxin treatment of cells reduced, but did not abolish, D5 agonist high-affinity binding sites, indicating D5 receptors couple to both Gs alpha and cholera toxin-insensitive G proteins. The interaction between D5 receptors and Gs alpha was confirmed by immunoprecipitation studies and by the ability of D5 receptors to stimulate adenylyl cyclase. Unlike D1 receptors, D5 receptors did not display any pertussis toxin-sensitive G-protein coupling to Go alpha or Gi alpha. D5 receptors were also not coupled to Gq alpha and were unable to mediate phosphatidylinositol metabolism. Instead, D5 sites appeared to be coupled to an AIF(-)4-sensitive, N-ethylmaleimide-resistant G protein. Anti-Gz alpha caused immunoprecipitation of 24.2 +/- 5.2% of G protein-associated D5 receptors, indicating coupling between D5 and Gz alpha. The coupling to Gz alpha was specific for D5 receptors, because similar associations were not detected between D1 receptors and Gz alpha.

Animals↗
PubMed1998

Ionizing radiation and TNF-alpha and stimulated expression of alpha1-antichymotrypsin gene in human squamous carcinoma cells.

Alpha-1 antichymotrypsin (ACT), a serine protease inhibitor, has been detected in several epithelial tumor cell types, but its role in response to therapy is not clear. We report here that exposure of primary head and neck squamous cell carcinoma (HNSCC)-derived cells (PCI-04A) to ionizing radiation (IR) or tumor necrosis factor-alpha (TNF-alpha) resulted in an increased level of ACT mRNA, although the induction patterns were different. IR treatment caused a transient stimulation of ACT mRNA, peaking at 3 h post-irradiation, whereas TNF-alpha-inducible ACT gene expression lasted for up to 24 h. The ACT mRNA was expressed in several epithelial and non-epithelial tumor cell types, and in different normal human tissues. In addition, when the ACT gene expression in PCI-04A cells was compared with the matched (from the same patient) metastatic HNSCC-derived cells (PCI-04B), increased steady-state level of the ACT mRNA was observed in PCI-04B cells. Taken together, these findings suggest that ACT may serve as an important marker for prognosis and therapy selection in HNSCC.

Carcinoma, Squamous Cell↗
PubMed1998

Adverse effects of chronic low level lead exposure on kidney function--a risk group study in children.

BACKGROUND: Children have been considered a risk group for lead (Pb) toxicity, mainly because of neurophysiological or neuro-cognitive deficits following Pb exposure. Blood Pb levels (b-Pb) of 100 microg/l currently have been defined as the lowest adverse effect level. The aim of this study was to compare, with the help of urinary markers, the kidney function of children with b-Pb just above this threshold with that of unexposed children, to assess from a nephrological point of view whether the current threshold is justified and whether children really are a particularly vulnerable risk group in terms of Pb-induced kidney damage. METHODS: In a cross-sectional study, 112 children, either from unexposed areas (controls, n=50) or Pb-contaminated areas (n=62), the latter partly with a known history of elevated b-Pb, were examined. Twenty nine urinary or serum markers mostly related to the function or integrity of specific nephron segments were determined (e.g. filtered plasma proteins, tubular enzymes, tubular antigens, eicosanoids). RESULTS: b-Pb were 39+/-13 microg/l in controls and 133+/-62 microg/l in exposed children. The main findings were increased excretion rates of prostaglandins and thromboxane B2, epidermal growth factor, beta2-microglobulin and Clara cell protein in the exposed children. A relationship between b-Pb and the prevalence of values above the upper reference limits was observed. CONCLUSIONS: With the help of urinary markers, nephron segment-specific effects of chronic low-level Pb exposure could be detected in children. The pattern of effects on glomerular, proximal and distal tubular and interstitial markers was similar to that previously observed in adults. The changes, however, occur at lower b-Pb levels than in adults. The current threshold appears to be justified also from a nephrological point of view, and children can indeed be considered a special risk group.

Biomarkers↗
PubMed1998

Does examination of urinary sediment identify individuals with Gulf War syndrome? A pilot study.

BACKGROUND: Many veterans who were involved in the Persian Gulf theater of operations have had a variety of unexplained physical complaints, collectively called the Gulf War syndrome or similar names. There has been much debate on the issue and numerous publications, both in the medical and the lay press. A method for examining urinary sediment that was developed in an effort to identify nonculturable bacteria has been used in Gulf War veterans and was the basis for intensive antimicrobial therapy in many of them. METHODS: We evaluated eight Gulf War veterans with complaints compatible with Gulf War syndrome. Subjects were from various parts of the United States. A detailed history and physical examination were performed. Urine was obtained before and after prostatic massage (men) or before and after pelvic examinations (women) and was tested by a previously described microscopic method as well as by culture and conventional Gram stain. Age- and sex-matched healthy control subjects were tested similarly and concurrently. RESULTS: Two female Gulf War veterans had findings of Candida albicans and Klebsiella pneumoniae by conventional culture. The same organism types were seen both by the special method and by conventional Gram stain. All other subjects and controls were completely indistinguishable. CONCLUSION: Examining the urinary sediment by this elaborate method does not differentiate persons with Gulf War syndrome from normal, healthy control subjects who were never in the Persian Gulf area.

Adult↗
PubMed1998

Diminished expression of renal dopamine D1A receptors in the kidney inner medulla of the spontaneously hypertensive rat.

BACKGROUND: Dysfunctional dopamine neurotransmission and greater than normal retention of salt have been found for renal proximal tubules of the spontaneously hypertensive rat OBJECTIVE: To determine whether there are differences between kidney D1A dopamine receptor distributions of spontaneously hypertensive rats and Wistar-Kyoto rats. METHODS: We examined the expression of D1A dopamine receptors in kidneys of spontaneously hypertensive rats and the normotensive Wistar-Kyoto rat through Western blots and immunocytochemistry, using highly specific antipeptide antibodies directed against the receptor. RESULTS: The specificity of the antisera was demonstrated by Western blot studies, using proximal tubules, from Wistar-Kyoto rats. The antiserum recognized a major polypeptide with Mr of 72 kDa and a minor protein of Mr 66 kDa, which were not detected either by antigen-adsorbed or by preimmune sera. In renal cortex of both Wistar-Kyoto rats and spontaneously hypertensive rats, D1A receptors were expressed at equivalent levels. In the inner medulla of Wistar-Kyoto rat, there was diminished (by 60%) expression of D1A receptors compared with that of the renal cortex. However, the expression of D1A receptors in the inner medulla in the spontaneously hypertensive rat was even more diminished (by 83%) relative to levels found in spontaneously hypertensive rat renal cortex. Immunocytochemical studies localized the D1A receptor protein in renal cortex primarily to epithelia of tubules. Relative to renal cortex, there was an overall decrease in staining intensity in the inner medulla both of Wistar-Kyoto rats and of spontaneously hypertensive rats. Compared with that of Wistar-Kyoto rat, the intensity of staining of D1A receptors in the inner medulla of spontaneously hypertensive rats was greatly diminished, confirming the Western blot analyses. The less than normal expression of D1A receptors in the inner medulla of spontaneously hypertensive rats might be of physiologic importance in the etiology of greater than normal retention of salt and hypertension in spontaneously hypertensive rats.

Animals↗
PubMed1998

Nifedipine-retard versus nifedipine-capsules for the therapy of hypertensive crisis in black patients.

In a randomized parallel-group placebo-controlled study, we compared the short-term hypotensive efficacy and the safety of a single administration of nifedipine-retard (20-mg tablets) with that of two administrations 6 h apart of nifedipine capsules (10 mg) in 10 and 11 black patients, respectively, with acute severe hypertension. Both groups had similar pretreatment blood-pressure (BP) values. Blood pressure was recorded at 10-min intervals for 12 h by using an automated device. In the first 3 h of treatment, nifedipine capsules induced a faster and greater hypotensive effect than nifedipine retard, which was associated with an increase in heart rate. At 2 h after treatment, nifedipine capsules decreased BP to levels (159 +/- 5/105 +/- 3 mm Hg) that were significantly lower than those reached by nifedipine-retard (175 +/- 4/118 +/- 4 mm Hg; p < 0.05). Both preparations induced a similar maximal BP decrease of approximately 30% of the placebo values, but the peak decrease of BP occurred significantly later with nifedipine-retard (283 +/- 31 min after administration) than with nifedipine capsules (100 +/- 14 min; p < 0.01). Four hours after administration, the hypotensive effect of nifedipine capsules was blunted, and a second administration was necessary, whereas nifedipine-retard reduced BP slowly and continuously for < or =12 h and more smoothly. Flush and headache were more frequently found with nifedipine capsules. We conclude that in black patients with hypertensive crisis, nifedipine capsules produce an abrupt decrease in BP that may be potentially harmful. Thus for patients suitable for treatment with nifedipine, nifedipine-retard is preferable because it effectively reduces BP for > or =12 h while achieving a rapid enough effect without critical short-term decreases in BP.

Administration, Oral↗
PubMed1998

Pilot study on the use of impression cytology specimens for quantitative assessment of the surface area of bulbar conjunctival cells.

PURPOSE: To assess whether impression cytology samples could be used to assess cell conjunctival cell surface areas, and to obtain an estimate of these for normal appearing cells vs. those with squamous metaplasia. METHODS: Small sheets of nasal bulbar conjunctival cells (c. 0.03 mm2) were obtained from 17 subjects aged 25 to 78 years by manual application of a 0.45 microm Millipore filter without topical anesthetic. Outlines of cells, visible as a rarefaction of the general cell cytoplasmic staining, were made on an optical overlay and then planimetry was carried out. RESULTS: Reasonable estimates (with +/-2.5%) of the average cell area can be obtained from samples containing contiguous sets of 100 cells. From 14 separate samples of normal cells [subjective assignment of nucleus:cytoplasm (N:C) ratios of 1:1 to 1:2], cell surface area values ranged from 11 to 426 microm2, with an overall average value of 108 +/- 43 microm2. Samples from individuals with symptoms suggestive of borderline dry eye tended to have slightly higher proportions of larger cells (so increasing the average cell area), and there was a trend for samples from older individuals to contain more smaller cells (so decreasing the average cell area). In marked contrast, cells showing evidence of squamous metaplasia and with N:C ratios of 1:6 or higher were found to have an average area of 543 +/- 76 microm2 (range 310 to 1529 microm2). CONCLUSIONS: Morphometry of impression cytology specimens is possible. The average cell size in normal individuals is considerably smaller than previously reported (108 vs. 585 microm2), but this is consistent with a range of studies on animal tissue using scanning electron microscopy.

Adult↗
PubMed1998

Heterogeneous location of the mupA high-level mupirocin resistance gene in Staphylococcus aureus.

Epidemiologically unrelated clinical isolates of Staphylococcus aureus with high-level resistance to mupirocin (MIC > or = 512 mg/L) were studied to determine the location of the mupA resistance gene. The gene was carried on plasmids of variable size, some of which were transferable in vitro. DNA hybridisation of genomic DNA from 85 isolates showed that mupA was located on EcoRI fragments of seven different sizes; the most frequently observed fragments were 7 kb (46 isolates) or 4.1 kb (21 isolates). All isolates retained a 1.6-kb Nco I fragment that hybridised with mupA probes, but showed heterogeneous hybridisation patterns after digestion with Hinc II. These data suggested that mupA may be conserved, but that variation occurs in the flanking DNA proximal to it. Amplification of spacer regions between mupA and closest proximal copy of IS257 yielded products of variable size and was consistent with the presence of IS257 in either orientation. It is proposed that IS257-mediated events are responsible for the heterogeneity observed. The location of mupA varied between epidemiologically unrelated isolates of the same strain, including isolates of EMRSA-16 -- one of the two predominant methicillin-resistant strains in UK hospitals at the present time -- and this correlated with variations in the digestion patterns of the mupirocin resistance plasmids. The variable location of mupA should be evaluated further as a potential epidemiological tool with which to monitor the spread of high-level mupirocin resistance in EMRSA-16 or other strains of S. aureus.

Anti-Bacterial Agents↗
PubMed1998

Time course of ADCw changes in ischemic stroke: beyond the human eye!

BACKGROUND AND PURPOSE: Using newly developed computerized image analysis, we studied the heterogeneity of apparent diffusion coefficient of water (ADCw) values in human ischemic stroke within 10 hours of onset. METHODS: Echo-planar trace diffusion-weighted images from 9 patients with focal cortical ischemic stroke were obtained within 10 hours of symptom onset. An Iterative Self-Organizing Data Analysis (ISODATA) clustering algorithm was implemented to segment different tissue types with a series of DW images. ADCw maps were calculated from 4 DW images on a pixel-by-pixel basis. The segmented zones within the lesion were characterized as low, pseudonormal, or high, expressed as a ratio of the mean+/-SD of ADCw of contralateral noninvolved tissue. RESULTS: The average ADCW in the ischemic stroke region within 10 hours of onset was significantly depressed compared with homologous contralateral tissue (626.6+/-76.8 versus 842.9+/-60.4x10(-6) mm2/s; P<0.0001). Nevertheless, ISODATA segmentation yielded multiple zones within the stroke region that were characterized as low, pseudonormal, and high. The mean proportion of low:pseudonormal:high was 72%:20%:8%. CONCLUSIONS: Despite low average ADCW, computer-assisted segmentation of DW MRI detected heterogeneous zones within ischemic lesions corresponding to low, pseudonormal, and high ADCw not visible to the human eye. This supports acute elevation of ADCw in human ischemic stroke and, accordingly, different temporal rates of tissue evolution toward infarction.

Acute Disease↗
PubMed1998

Efficacy and tolerability of carbamazepine for agitation and aggression in dementia.

OBJECTIVE: The efficacy, safety, and tolerability of carbamazepine in the treatment of agitation and aggression associated with dementia were assessed. METHOD: In a 6-week, randomized, multisite, parallel-group study of 51 nursing home patients with agitation and dementia, individualized doses of carbamazepine were compared with placebo. Except for a physician monitor and a pharmacist, all participants were blind to treatment. The primary outcome measures were the Brief Psychiatric Rating Scale (BPRS) and Clinical Global Impression (CGI) global improvement rating. Secondary measures included measures of behavior, aggression, cognition, functional status, staff time, safety, and tolerability. Intent-to-treat analysis was performed. RESULTS: The modal carbamazepine dose at 6 weeks was 300 mg/day, and a mean serum level of 5.3 micrograms/ml was achieved. The study was terminated after a planned interim analysis showed that carbamazepine provided more benefit than did placebo. Over 6 weeks the mean total BPRS score decreased 7.7 points for the carbamazepine group and 0.9 for the placebo group, and the weekly scores showed a gradual divergence between the two groups. CGI ratings showed global improvement in 77% of the patients taking carbamazepine and 21% of those taking placebo. Secondary analyses confirmed that the positive changes were due to decreased agitation and aggression. The drug was generally well tolerated, and no change in cognition or functional status occurred. The perception of staff time needed to manage agitation showed a decrease for carbamazepine but not placebo. CONCLUSIONS: This controlled study showed significant short-term efficacy of carbamazepine for agitation with generally good safety and tolerability.

Aged↗
PubMed1998

Quality of history taking in patients with aortic dissection.

STUDY OBJECTIVES: Aortic dissection generally is an acute catastrophe. Rapid diagnosis is critical. We hypothesized that the quality of history taking contributes to the accuracy of diagnosis in patients with dissection. DESIGN: Retrospective chart review of 83 patients, whose diagnosis of aortic dissection was confirmed by autopsy, surgery, CT scan, echocardiogram, or angiogram. The quality of the initial history was reviewed using predetermined criteria. The physicians' initial clinical impressions were recorded. RESULTS: The examining physician correctly suspected aortic dissection after the initial clinical evaluation in 54 of 83 patients (65%). Only 33 of 78 patients with symptoms (42%) were asked about the quality, location, and onset of their pain, the three descriptors identified a priori as important. In 19 patients (24%), only zero or one descriptor was recorded. When all three questions were asked, dissection was suspected in 30 of 33 patients (91%); when zero, one, or two questions were asked, dissection was suspected in 22 of 45 patients (49%). CONCLUSION: Despite important advances in diagnostic imaging, accurate diagnosis of aortic dissection requires an accurate history. In our series, the quality of initial history was associated with the accuracy of the initial clinical impression in patients with aortic dissection.

Aortic Dissection↗
PubMed1998

The value of a phenol red impregnated thread for differentiating between the aqueous and non-aqueous deficient dry eye.

To determine the clinical viability of a phenol red impregnated cotton thread in differentiating between normal, aqueous deficient and non-aqueous deficient dry eyes. Subjects were recruited on the basis of subjective symptoms, tear stability, rose bengal staining, Schirmer test, conjunctival hyperaemia, patency and number of meibomian glands, presence of mucin strands, appearance of lower tear meniscus. Based on the outcome of the tests, subjects were categorised as either aqueous deficient dry eyes, non-aqueous dry eyes or normals. Subjects were randomised and a thread was applied by inserting into the lower fornix of the right eye and leaving the thread in place for 120 sec. All data was collected under similar ambient conditions. After gathering all the data, the codes were broken. Mean (+/- S.D.) thread wetting values were, all dry eyes (n = 59) 18.4 mm (5.9). Aqueous deficient dry eyes (n = 35), 15.5 mm (4.6). Non-aqueous deficient dry eyes [n = 24], 22.7 mm (5.0). For the normals (n = 38), 19.4 mm (5.0). Differences between (i) normals and aqueous deficient dry eyes and (ii) aqueous deficient and non-aqueous deficient dry eyes were significant (p = 0.01). Difference between all dry eyes and normals was not significant. For the aqueous deficient and non-aqueous deficient dry eyes only, using a cut-off value of 20 mm the calculated sensitivity and specificity values were 86% and 83% respectively. This cotton thread test can effectively differentiate between aqueous deficient and non-aqueous deficient dry eye.

Adult↗