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Biomedical subjects

H Patel

Publications and source records attributed to H Patel.

At least 19 recordsLinked to original sources
PubMed1992

Structure of striated microtubule-associated fibers of flagellar roots. Comparison of native and reconstituted states.

Several fiber systems are associated with the flagella and basal bodies of eukaryotic cells. Apart from the contractile and Ca(2+)-sensitive system-II fibers, these include the noncontractile system-I fibers that run parallel to flagellar root microtubules. Using electron microscopy and image reconstruction, we have investigated the structure of the system-I fibers of the flagellate green alga Spermatozopsis similis. The fibers were observed in three different states: (1) in situ, (2) after isolation of the intact fibers, (3) after disassembly and reconstitution of fibers in vitro from their 34 kDa subunit protein. The fibers are highly ordered; they show a constant repeat of 28 nm, they are polar, and they contain several transverse and longitudinal striations. A model is discussed showing the system-I fiber to be built from rod-like molecules with a staggered arrangement and identical polarities.

Chlorophyta↗
PubMed1992

Eicosatetraynoic and arachidonic acid-induced changes in cell membrane fluidity consonant with differences in computer-aided design-structures.

ETYA (5,8,11,14-eicosatetraynoic acid), a competitive analogue of arachidonic acid (AA), inhibits the proliferation of U937 (human monoblastoid) and PC3 (human prostate) cancer cells, without the overt cytotoxicity associated with AA at similar concentrations. The mechanism of inhibition is not established. ETYA at 100 microM acutely increased whole cell and isolated microsomal membrane fluidity of both cell lines to a greater extent than arachidonic acid. PC3 cells incubated with ETYA for 72 h evidenced increased membrane fluidity. This was measured by the fluorescence polarization parameter, R, using the probes TMA-DPH and DPH for whole cell and isolated membrane fractions, respectively. Compared with whole cells, isolated membranes yielded a 10-20-fold increase in fluorescence intensity. The intramolecular conformational profiles of both ETYA and AA were explored using a combination of molecular mechanics energy minimization and molecular dynamics simulation. While it is possible that not all of the low energy conformational states of either molecule were sampled, the large number of low-energy conformers determined for ETYA correspond to kink deformed conformers relative to the family of AA conformers. These kinks make the molecular cross sections of ETYA larger than AA and arise from the four alkyne bond geometries. This structural finding is consistent with ETYA's greater effect on membrane fluidity. Dissociation between the extent of change in membrane fluidity due to ETYA or AA and inhibition of DNA synthesis can suggest that either (A) increased fluidity and inhibition of DNA synthesis are independent, or as we believe more likely, (B) greater membrane fluidity evoked by ETYA is important for inhibiting DNA synthesis, while changes induced by AA are insufficient or differ qualitatively from those required to initiate and sustain these nonlethal events.

Arachidonic Acids↗
PubMed1992

Aerocele, an unusual complication of anterior cricoid split.

Since its introduction, the anterior cricoid split has proven to be a safe and effective procedure for the management of infants with acquired subglottic stenosis. In this article we report an unusual complication--an aerocele, which occurred on the 14th day following an anterior cricoid split on a 9-month-old child. The possible etiology and successful management of the aerocele are reviewed.

Air↗
PubMed1992

Prostate specific antigen levels after radical prostatectomy in patients with organ confined and locally extensive prostate cancer.

A total of 230 patients with localized prostate cancer underwent radical retropubic prostatectomy at UCLA (pathological stage T1-3 N0, M0). Classification into groups included 115 patients with organ confined disease (group 1), 82 with invasion into or through the capsule (group 2) and 33 with seminal vesicle involvement (group 3). Median followup was 48 months. The 10-year, cause-specific survival was 96%, 90% and 63%, and 5-year, clinical, disease-free survival was 91%, 79% and 58% for the 3 groups, respectively. Recent prostate specific antigen (PSA) levels were measured in most patients, even those operated upon many years ago. Of the patients 41 had detectable (0.4 ng./ml. or greater) PSA levels without any other clinical evidence of progression and 15 with clinical evidence of progression had PSA levels in the detectable range at the time of clinical progression. When isolated detectable PSA was also considered an indicator of progression the 5-year and 10-year, disease-free rates were 61% and 41%, respectively. These data show that radical prostatectomy performed in patients with even microscopic invasion into the capsule, positive margins and seminal vesicle involvement is associated with a higher clinical progression rate than organ confined disease. If isolated detectable PSA is also considered an indicator of recurrence the disease-free survival after radical prostatectomy might be less than indicated by previous studies. The relationship among survival, local tumor extension and PSA must be carefully examined.

Adult↗
PubMed1992

Comparison of Sentinel and Bactec blood culture systems.

AIMS: To evaluate the Sentinel automated blood culture system and to compare its performance with that of Bactec. METHODS: The Sentinel blood culture system was evaluated in three centres. The performance of the system was assessed in comparison with the routine blood culture method used in these centres, the Bactec system. RESULTS: Blood culture sets (n = 2180) consisting of Sentinel aerobic and anaerobic, and Bactec aerobic and anaerobic bottles yielded 218 (10%) clinically important isolates. One hundred and fifty five (71%) of the isolates were detected by both systems; 35 (16%) were detected by Sentinel only; and 28 (13%) by Bactec only. For the duration of the evaluation, the Sentinel system was deliberately configured so that it was impossible to detect positive results during the first 12 hours. The times to positivity after the first 12 hours were similar. Data gathered during and subsequent to the evaluation have been used by the manufacturer to refine the algorithm so that positive results can be detected at a minimum of 2.25 hours. CONCLUSIONS: After a period of familiarization the Sentinel system was considered easy to use. Sentinel is a useful addition to the methods available for the detection of bacteria in blood cultures.

Bacteriological Techniques↗
PubMed1991

Rapid culture confirmation of herpes simplex virus by a monoclonal antibody-based enzyme immunoassay.

Rapid confirmation of herpes simplex virus (HSV) is essential in many clinical settings. Viral isolation in cell culture is the standard method for diagnosing HSV infection, with confirmation by specific immunological staining. The performance of the Rapid Absorbent Matrix Pad (RAMP) HSV culture confirmation test was evaluated with specimens obtained from 71 patients with suspected HSV infection and inoculated into African green monkey kidney cell lines. Forty-one culture-positive specimens were confirmed to be HSV by both the RAMP HSV test and the Bartels HSV immunoperoxidase test. Thirty immunoperoxidase-negative specimens were also negative in the RAMP HSV test. The sensitivity and specificity of the RAMP HSV test were 100%. Twelve specimens positive for cytomegalovirus, adenovirus, or enterovirus tested negative by the RAMP HSV test. Thus, the RAMP HSV test was faster than, easier to perform than, as sensitive as, and as specific as other well-documented confirmation methods.

Antibodies, Monoclonal↗
PubMed1991

Altered adrenocorticotropin, corticosterone and oxytocin responses to stress during chronic salt load.

We have investigated the effects of stress on the plasma levels of adrenocorticotropin (ACTH), corticosterone and oxytocin (OT) in rats given 2% saline to drink for 12 days. Plasma ACTH levels were markedly decreased from 972 +/- 165 pg/ml in the control animals on water to 349 +/- 114 pg/ml in animals given 2% saline to drink. Stress-induced release of ACTH observed in animals on water (controls = 972 +/- 165 pg/ml and stressed animals = 1,439 +/- 105 pg/ml) was completely abolished following 2% saline treatment for 12 days (controls = 349 +/- 114 pg/ml and stressed animals = 205 +/- 27 pg/ml). After 2% saline, plasma corticosterone levels were unaltered in control and stressed animals as compared to control animals on water in which stress increased plasma corticosterone from 28.8 +/- 7.9 to 99.5 +/- 8 ng/ml. In contrast to ACTH, the OT response to stress was intact in animals on 2% saline despite raised plasma OT in the control group due to the osmotic stimulus. Removal of the source of circulating glucocorticoids by adrenalectomy partially restored both basal levels of ACTH and the response to stress in animals on 2% saline. Our results demonstrate that 2% saline treatment activates an inhibitory mechanism over the release of ACTH.

Adrenalectomy↗
PubMed1991

Lactation abolishes corticotropin-releasing factor-induced oxytocin secretion in the conscious rat.

We have assessed the response of plasma oxytocin (OT) to intracerebroventricular CRF-41 in both virgin female and lactating rats. In virgin rats CRF-41 resulted in an increase in plasma OT from 5-30 min after administration. In lactating rats, however, there was a complete abolition of the OT response, even at the highest dose of CRF-41. These data demonstrate another feature of the hormone nonresponsiveness apparent during lactation and suggests that one of the reasons for the lack of stress responses could be a down-regulation of the response to endogenously released CRF-41.

Animals↗
PubMed1991

The interaction of boar sperm proacrosin with its natural substrate, the zona pellucida, and with polysulfated polysaccharides.

Boar sperm acrosin is an acrosomal protease with trypsin-like specificity, and it functions in fertilization by assisting sperm passage through the zona pellucida by limited hydrolysis of this extracellular matrix. In addition to a proteolytic active site domain, acrosin binds the zona pellucida at a separate binding domain that is lost during proacrosin autolysis. In this study, we quantitate the binding of proacrosin to the physiological substrate for acrosin, the zona pellucida, and to a non-substrate, the polysulfated polysaccharide fucoidan. Binding was analogous to sea urchin sperm bindin that binds egg jelly fucan and the vitelline envelope of sea urchin eggs. Proacrosin was found to bind to fucoidan and to the zona pellucida with binding affinities similar to bindin interaction with egg jelly fucan. These interactions were competitively inhibited by similar relative molecular mass polysulfated polymers. Since bindin and proacrosin have distinctly different amino acid sequences, their interaction with acidic sulfate esters demonstrates an example of convergent evolution wherein different macromolecules localized in analogous sperm compartments have the same biological function. From cDNA sequence analysis of proacrosin, this binding may be mediated through a consensus sequence for binding sulfated glycoconjugates. Proacrosin binding to the zona pellucida may serve as both a recognition or primary sperm receptor, as well as maintaining the sperm on the zona pellucida once the acrosome reaction has occurred.

Acrosin↗
PubMed1991

Lanosterol 14 alpha-demethylase (P45014DM): effects of P45014DM inhibitors on sterol biosynthesis downstream of lanosterol.

Lanosterol 14 alpha-demethylase (P45014DM) is the cytochrome P450 enzyme complex responsible for an early step in cholesterol biosynthesis, namely the 14 alpha-demethylation of lanosterol. We have synthesized a novel series of steroidal substrate analogues, designed to be specific and potent inhibitors of P45014DM. We describe here the effects of these compounds on sterol biosynthesis downstream from lanosterol, focusing ultimately on their efficacy as inhibitors of cholesterol biosynthesis. Results using a radio-high performance liquid chromatography (HPLC) assay show that in rat liver microsomal preparations, with [24,25-3H]dihydrolanosterol as substrate, the compounds do indeed inhibit the biosynthesis of sterols downstream from lanosterol. A range of inhibitory potencies was observed, and the key enzyme being inhibited was believed to be P45014DM. Inhibitor efficacy was readily correlated with non-metabolized [24,25-3H]dihydrolanosterol, formation of 4,4-dimethyl-cholest-8-en-3 beta-ol, and formation of lathosterol, a sterol believed to be an excellent indicator of whole body cholesterol biosynthesis in humans.

Animals↗
PubMed1990

The effects of chronic obstructive airways disease on the ability to drive and to use a roadside alcolmeter.

Subjects with chronic obstructive airways disease may have difficulty with the roadside alcolmeter. Twenty-six subjects with a FEV1/FVC less than 60% were asked to use an alcolmeter simulator. Only ten were able to produce the necessary flow rate of 28 l min-1 for a minimum of 2.7 s, two could produce the same total volume (1.25 l) at 10 l min-1 for 7.5 s, five could only expel 10 l min-1 for 4.5 s, and nine were unable to trigger the alcolmeter at even these very low flow rates. Subjects with an FEV1 of less than 1.51 or FEV1% predicted less than 50% were very unlikely to be able to activate the alcolmeter. Ten healthy subjects were investigated to assess the accuracy of the roadside alcolmeter at a flow rate of 10 l min-1 compared to 40 l min-1. No significant difference was found in breath alcohol levels between the two flow rates. It is proposed that some modification could be made to the roadside alcolmeter, without affecting its accuracy, to allow some subjects with chronic obstructive lung disease to activate the device. A postal survey of 284 subjects with a FEV1/FVC less than 60% was carried out. Of those who were drivers or exdrivers, 24.7% had had to stop or reduce their driving because of their respiratory disease. This group had a significantly lower FEV1% predicted (P = 0.035) than those whose driving was unaffected.

Adult↗
PubMed1990

Gas chromatography of C19 and 17-oxogenic steroids in urine.

17-oxogenic steroids have been analysed by gas chromatography (GC) with capillary column and flame ionization detector. The best separation of steroid products was gained after ethyloxime-trimethylsilyl ether formation. The value of the GC method as a screening procedure for patients with suspected adrenal disease is illustrated in selected cases where the diagnosis was equivocal from data derived by RIA analysis of plasma steroids.

17-Hydroxycorticosteroids↗
PubMed1989

History of separation anxiety in patients with panic disorder and depression and normal controls.

The frequency and severity of separation anxiety for subjects with panic disorder and major depression was compared with that for normal controls. The subjects were diagnosed according to DSM-III criteria. Each subject completed a questionnaire consisting of 9 items derived from DSM-III criteria for separation anxiety disorder. The incidence of separation anxiety and its severity were significantly higher for the panic disorder subjects than for normal controls but there was no significant difference between depressed and panic disorder subjects. Panic disorder subjects with a history of separation anxiety disorder had a significantly earlier onset of panic attacks.

Adult↗
PubMed1989

Idiopathic unilateral hyperlucent lung.

The entity of unilateral hyperlucent lung in the adult is presented as a disease which has its origins in childhood and carries the potential for cardiopulmonary morbidity.

Adult↗
PubMed1989

Indomethacin therapy in premature infants with patent ductus arteriosus--determination of therapeutic plasma levels.

To determine the therapeutic range of plasma indomethacin levels for ductus closure, we evaluated the ductus response and renal side effects on two therapeutic regimens using different dosage; regimen I received 0.3 mg/kg q 24 h for a maximum of 3 doses, and regimen II received 0.1, 0.2 and 0.3 mg/kg at 24-hour intervals, for a maximum of 3 doses if needed. Infants in regimen I had significantly higher plasma indomethacin and higher ductus response rate than infants in regimen II. Urine output (U/O) was comparable between the regimens, but serum sodium was lower in regimen I than in regimen II. In both regimens, U/O and serum sodium return to normal by 72 h. The plasma indomethacin levels at 12 h after 1 dose correlated significantly with ductus response and hyponatremia. There appeared to be a minimal level of plasma indomethacin above which U/O decreased; with a plasma level greater than 170 ng/ml the majority (greater than 97%) of infants showed a decrease in U/O. While there was a 50% or greater chance that ductus would close when the plasma levels reached 600 ng/ml or more, a great proportion of infants would also develop renal side effects. Thus, a safe therapeutic range of plasma indomethacin appeared to be very narrow. However, when the dose of indomethacin is increased to optimize constrictive response, there is no significant increase in incidence and severity of renal adverse effects. In view of the transient nature of renal side effects, they should not hinder indomethacin therapy if ductus closure is indicated.

Ductus Arteriosus, Patent↗
PubMed1988

Acute staphylococcal septic arthritis: the effect of cloxacillin therapy in an avian model.

An experimental model of acute staphylococcal septic arthritis in chickens was used to study the effect of different therapeutic regimens of the antibiotic cloxacillin on the natural history of the disease. Three different therapeutic regimens were used in order to assess the effect of increasing the frequency and of delaying the commencement of administration. The results were assessed by measurement of animal growth rate, clinical condition, bacterial and leukocyte counts in synovial fluid, and histological appearance. An inadequate dosage regimen (a single daily dose) prevented spread of bacteria but did not control abscesses. Delay in commencing treatment permitted persistence and spread of abscesses with destruction of the secondary (epiphyseal) ossification center and even transphyseal spread into metaphyseal bone. Repair by fibroblasts was mainly seen in articular and epiphyseal cartilage but was not seen in the epiphyseal ossification center during the duration of the experiments (up to 18 days). Synovial fluid sampling with measurement of leukocyte and bacterial concentrations appears to be a useful guide to the effectiveness of treatment, because the numbers of cells correlate with the pathological process.

Acute Disease↗
PubMed1988

Use of lacZ expression to monitor transcription.

For use in monitoring transcription in operon fusion, we have constructed a lacZ sequence with the initiation codon ATG and the Escherichia coli consensus Shine-Dalgarno site. There are unique restriction endonuclease sites flanking the sequence to allow easy isolation of the lacZ sequence with or without the Shine-Dalgarno site. We have placed this lacZ sequence behind the bovine growth hormone (BGH) gene and found that the lacZ product beta-galactosidase synthesized reflects the level of BGH-specific mRNA.

Animals↗