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Biomedical subjects

S G Joshi

Publications and source records attributed to S G Joshi.

At least 19 recordsLinked to original sources
PubMed2003

Liquid level sensor using ultrasonic Lamb waves.

This paper describes a novel, noninvasive method for measurement of liquid level in closed metal tanks that are under high pressure. It is based on the use of ultrasonic Lamb waves propagating along the tank wall. Contact with liquid substantially changes the characteristics of these waves and this can be used as an indicator of liquid presence. Theoretical analysis shows that the symmetric and antisymmetric Lamb wave modes, both fundamental and higher order, are sensitive to presence of the liquid. The optimal wave frequency depends on the thickness of the tank wall and wall material. A prototype level sensor based on this principle has been developed. It uses two pairs of wedge transducers to generate and detect Lamb waves propagating along the circumference of the gas tank. An operating frequency of 100 kHz is found to be optimal for use with tanks having a wall thickness of 30-50 mm. Prototype sensors developed under this program have been used successfully in oil fields in the far northern region of Russia.

Materials Testing↗
PubMed2002

Improved equivalent circuits for acoustic plate wave devices.

This paper presents improved equivalent circuits for the analysis and design of acoustic plate wave devices. The method uses a mixed equivalent circuit for the interdigital transducer consisting of both active and passive sections placed on the surface of a piezoelectric plate. The values of the various circuit elements are obtained by carrying out a best fit between theoretical and experimental frequency dependence of the real and imaginary parts of transducer input impedance. Knowledge of the equivalent circuit parameters allows one to optimize design of the devices. The method has been successfully employed for the design of one-port shear-horizontal wave resonators on Y-X lithium niobate plates. The proposed method can also be utilized for determining acoustic wave velocity with high accuracy.

Journal Article↗
PubMed2001

Investigation of acoustic waves in thin plates of lithium niobate and lithium tantalate.

The general properties of fundamental antisymmetric A0, symmetric S0, and shear horizontal SH0 acoustic waves propagating in thin piezoelectric plates have been theoretically investigated on samples of lithium niobate (LiNbO3) and lithium tantalate (LiTaO3). The results obtained will be useful for a proper development of various physical, chemical, and biological sensors and devices for signal processing based on plate acoustic waves.

Letter↗
PubMed2001

Influence of conducting layer and conducting electrode on acoustic waves propagating in potassium niobate plates.

The influence of a thin conducting layer and a conducting electrode on the characteristics of acoustic waves propagating in thin plates of potassium niobate is investigated theoretically. The variations in velocity and attenuation as high as 50% and 30 dB per wavelength, respectively, can be achieved for a change in conductance of the thin film layer from 10(-7) to 10(-5) S.

Letter↗
PubMed2001

Shear-horizontal acoustic waves in piezoelectric plates bordered with conductive liquid.

The influence of a conductive liquid on the characteristics of shear-horizontal acoustic waves of zeroth order (SH0 mode) propagating in thin piezoelectric plates of lithium tantalate, lithium niobate, and potassium niobate was investigated. Experimental results obtained for SH0 mode devices fabricated on lithium niobate plates are found to be in good agreement with theory. The data presented in this paper is useful for a proper design of various acoustic wave sensors operating in contact with conductive liquids.

Letter↗
PubMed2001

Epidemiology of cholera--a five year study.

A total of 286 strains of Vibro Cholerae were isolated and tested over a period of five years. The strains were identified by standard methods and confirmed by slide agglutination tests with polyvalent, Ogawa and Inaba antisera. The non-agglutinating strains were tested with O-139 antisera. The maximum number of cases were found in the age group of 0-10 years. The number of females affected was more than the males. V. cholerae O-139 was isolated in the year 1998 and then again in 2000. V. cholerae serotype Inaba was found only in the year 1999. All of the other isolates belonged to the serotype Ogawa. The periodic shift between O1 and O-139 serogoups is reminiscent of the shifts from the Ogawa to the Inaba serotypes periodically witnessed among V. cholerae, possibly mediated by the immune pressure in the population.

Adolescent↗
PubMed2000

Neonatal gram-negative bacteremia.

A 22 months prospective study of neonatal gram-negative bacteremia was undertaken in a 15 bed NICU to find out the incidence and antibiotic resistance patterns. Clinically suspected 1326 cases of neonatal sepsis were studied during this period. More than 25% of the cases were microbiologically positive for sepsis. Among 230 (67.2%) cases of gram-negative bacteremia, the predominant isolates were Pseudomonas aeruginosa (38.3%), Klebsiella pneumoniae (30.4%), Escherichia coli (15.6%) and Acinetobacter sp. (7.8%). Fifty-nine per cent of the neonates were born in hospital while 41% were from community and referral cases. Lower respiratory tract infection, umbilical sepsis, central intravenous line infection and infection following invasive procedures were the most commonly identified sources of septicemia. Prematurity and low birth weight were the main underlying conditions in 60% of the neonates. Total mortality was 32%. Increased mortality was mainly associated with neutropenia, nosocomial infection and inappropriate antibiotic therapy. Resistance was increasingly noted against many antibiotics. The isolates were predominantly resistant to extended spectrum cephalosporins (25%-75%), piperacillin (68%-78%), and gentamicin (23%-69%). The commonest microorganisms causing gram-negative bacteremia were Pseudomonas aeruginosa followed by Klebsiella pneumoniae. The community-acquired bacteremia was mainly due to E. coli. The proportion of preterm and low birth weight babies was significantly high, and the major contributing factor in total mortality. Sensitivity to different antibiotics conclusively proved that a combination of ampicillin + sulbactam with amikacin or ampicillin + sulbactam with ciprofloxacin is most effective.

Bacteremia↗
PubMed1995

Fas antigen-mediated apoptosis in human granulosa/luteal cells.

The Fas antigen is a transmembrane receptor that can trigger apoptosis in a variety of tumor and hematopoietic cells. Ovarian follicular atresia and luteolysis are thought to occur by apoptosis. Using reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry, we demonstrated that human granulosa/luteal cells express the Fas antigen. An anti-human Fas antigen monoclonal antibody (Fas mAb; clone CH-11), which induces apoptosis in other cell types by binding to the Fas antigen, induced significant cell death (30%) in cultures pretreated with interferon gamma (IFN gamma). This agrees with studies on tumor cell lines showing that IFN gamma enhances cytotoxic effects of Fas mAb. Granulosa/luteal cells exhibited morphological characteristics typical of apoptosis, including membrane blebbing and condensed chromatin. DNA fragmentation into oligonucleosomal units of approximately 180 bp, typical of apoptosis, was detected at elevated levels in Fas mAb-treated cultures via 3' end-labeling and gel electrophoresis. Examination of cultured cells in situ for apoptotic DNA cleavage by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end-labeling (TUNEL) indicated that more apoptotic death occurred in Fas mAb-treated cultures than in control cultures. Effects of hCG-induced luteinization of cultures on Fas mAb-induced cytotoxicity was examined: combined pretreatment with IFN gamma and hCG induced a synergistic increase in Fas mAb-induced cytotoxicity (40%) over that obtained with IFN gamma-pretreatment alone (15%). In summary, granulosa/luteal cells express the Fas antigen and are sensitive to Fas mAb-induced apoptosis. Human CG synergized with IFN gamma to increase Fas mAb-induced death.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1995

Chlamydia trachomatis in pelvic inflammatory disease.

The prevalence of genital Chlamydia trachomatis infection and some epidemiologic factors associated with it were studied in 273 pelvic inflammatory disease (PID) patients attending Gynaecologic clinic, Government Medical College, Nagpur. For detection of chlamydial antigen Pharmacia Diagnostics Chlamydia EIA test was used. This study revealed an overall positivity rate of 33% for C. trachomatis infection in PID patients. Of the hypothesised risk factors low socioeconomic status, history of sexual contacts with multiple partners and use of intrauterine devices (IUD) were significantly associated with C. trachomatis infections. However, use of oral contraceptives, barrier contraceptives and increasing age were found to be protective factors for C. trachomatis infection. Thus considering the significant contribution of C. trachomatis in etiology of PID and its independent association with some epidemiologic risk factors, extensive epidemiologic measures are recommended for prevention of these infections.

Adult↗
PubMed1994

Emergency contraception alters progesterone-associated endometrial protein in serum and uterine luminal fluid.

OBJECTIVE: To evaluate the effect of high-dose oral contraceptives on serum and uterine luminal fluid progesterone-associated endometrial protein in the luteal phase. METHODS: Five ovulatory women participated in the study. In a control cycle, serum and uterine lavage samples were collected on luteal day 11. In the next cycle, on luteal day 9, the participants were given two 50-micrograms ethinyl estradiol-norgestrel tablets, repeated 12 hours later. Serum and uterine lavage samples were collected 48 hours (luteal day 11) after the last dose and analyzed by two-dimensional polyacrylamide gel electrophoresis and radioimmunoassays of the serum. RESULTS: Progesterone-associated endometrial protein levels were lower in sera from treated compared with control cycles. Analysis of serum levels of this protein by two-dimensional polyacrylamide gel electrophoresis did not reveal bands corresponding to the known size and charge characteristics (27 kd and pI of 4.9) in either control or treatment samples. On the other hand, in uterine lavage samples, a complete suppression of the 27-kd, pI-4.9 species was evident after treatment. CONCLUSION: High-dose ethinyl estradiol-norgestrel emergency contraception effectively suppresses progesterone-associated endometrial protein in the midluteal uterus, potentially altering the endometrial environment unfavorably and affecting the survival of the early embryo.

Contraceptives, Oral, Hormonal↗
PubMed1991

The role of measurement of progestagen-associated endometrial protein in predicting adequate endometrial differentiation.

Late secretory endometrium synthesizes and secretes progestagen-associated endometrial protein (PEP), which is measurable in the serum of cycling women, and has been shown to increase in concentration during the luteal phase of the normal menstrual cycle. The purpose of this study was to determine the utility of serum PEP as a predictor of normal or inadequate luteal phase endometrial differentiation. One-hundred-and-twenty-five endometrial biopsies were taken within 4 days of a subsequent menstrual period, during the course of evaluation of infertility or recurrent abortion. Twenty-one of these biopsies demonstrated glandular/stromal asynchrony. Thirteen patients exhibited 'out-of-phase' endometrial biopsies and 91 patients had 'in-phase' biopsies. Mean PEP values significantly increased from the mid-luteal phase to the late luteal phase. Mean PEP values for patients with in-phase biopsies (43.92 units/ml) were not significantly different from those with out-of-phase biopsies (25.24 units/ml, P = 0.0942). PEP values for patients with asynchronous biopsies were intermediate. Use of clomiphene citrate did not affect these results.

Biopsy↗
PubMed1987

Progestin-dependent human endometrial protein: a marker for monitoring human endometrial function.

Progesterone (P), which is the major secretory product of the corpus luteum (CL) is the key hormone of pregnancy. CL defects that cause P to be secreted for too brief a period or at too low a rate are associated with an underdeveloped or inadequate endometrium which is incapable of supporting pregnancy. Some investigators, therefore, have recommended the use of exogenous P support in chronic CL defect patients who wish to conceive. However, the mechanisms by which P regulates endometrial function are poorly understood and there is no suitable, non-invasive method to monitor in individual patients the endometrial response to either endogenous or exogenous progesterone. We therefore initiated a search for progesterone-dependent endometrial protein(s) which might serve as a marker to assess effects of progestin therapy on endometrial function, and which might also afford insight into the mechanism of P action. We have detected a hormone-dependent endometrial protein designated "progestagen-associated (or -dependent) endometrial protein" or PEP. PEP is a glycoprotein (molecular weight approximately 47,000) which is synthesized in the endometrial glands and secreted into the blood. Its synthesis increases dramatically during pregnancy, as indicated by a more than 1000-fold greater PEP concentration in the decidua. PEP is not synthesized by the immature placenta, but binds to placental cell membranes. In normally cycling women, the serum PEP concentration increases in an exponential manner during the late luteal phase. In cycling infertile women, a direct relationship was found to exist between serum PEP levels they attained in the late luteal phase and their endometrial development, the serum levels being subnormal in women with inadequate endometrium. Menstrual cycles that are anovulatory or with a CL-defect are associated with low luteal phase serum PEP levels. In both pre- and post-menopausal women, serum PEP levels increase following a progestin challenge, demonstrating that PEP is indeed a progestin-dependent protein. Very low luteal phase serum PEP levels are encountered in some women who do not conceive following in vitro fertilization and embryo transfer (IVF/EF), suggesting that endometrial inadequacy is a major cause of failure in this procedure. In patients who undergo ovarian stimulation by exogenous hormones but do not conceive following IVF/ET, luteal phase serum PEP levels are markedly higher in those who receive luteal phase P support than those with no support.(ABSTRACT TRUNCATED AT 400 WORDS)

Decidua↗
PubMed1986

Luteal phase concentrations of a progestagen-associated endometrial protein (PEP) in the serum of cycling women with adequate or inadequate endometrium.

We previously demonstrated that the human endometrium synthesizes and secretes a specific protein designated "Progestagen-associated Endometrial Protein" or PEP. This work was undertaken to determine luteal phase levels of PEP in serum of cycling women with histologic evidence of adequate endometrium (endometrium in phase) or inadequate endometrium (endometrium out of phase by 3-4 days). The results provide a normative curve with 95% confidence limits for serum PEP concentrations vs normalized cycle day in women with adequate endometrium (judged by histologic endometrial dating), and indicate that the PEP concentration increases exponentially after day 22, with a mean doubling time of 2.95 +/- 1.60 (mean +/- SD) days (based on serial data from 13 women). More importantly, the proportion of serum PEP values falling outside of the 95% confidence limits was significantly greater (p less than 0.001) in women with inadequate endometrium (83%) than in women with adequate endometrium (16%). Therefore, determination of PEP in serum, rather than the more invasive endometrial biopsy examination, may serve as a method of choice for evaluating endometrial adequacy in infertile women.

Endometrium↗
PubMed1986

Serum and peritoneal fluid proteins in women with and without endometriosis.

We examined the proteins in serum and peritoneal fluid of women with endometriosis (and of healthy controls) for evidence of an autoimmune response that might account for their impaired fertility. No antibodies against endometrial glycoproteins or against "progestin dependent endometrial protein" (PEP) were found in any serum or peritoneal fluid sample. Levels of PEP were not different in serum from women with moderate to severe endometriosis (n = 6), with mild endometriosis (n = 21), or from disease-free cycling controls (n = 19). PEP levels in peritoneal fluid from mild endometriosis and from controls did not differ but were elevated ten times in fluid obtained in the secretory phase from women with moderate to severe disease. This suggests that PEP levels in peritoneal fluid reflect the extent of ectopic endometrial growth. The salient finding was a heretofore undescribed protein (mol wt 70,000) in secretory phase peritoneal fluid samples (18/20) and its absence during the proliferative phase (0/35).

Ascitic Fluid↗