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Biomedical subjects

A Pai

Publications and source records attributed to A Pai.

15 recordsLinked to original sources
PubMed2007

OEIS complex: prenatal ultrasound and autopsy findings.

OBJECTIVE: To describe prenatal ultrasound and autopsy findings in fetuses with OEIS (omphalocele, bladder exstrophy, imperforate anus, spina bifida) complex. METHODS: This was a retrospective study of the nine cases with OEIS complex diagnosed at our center using detailed fetal ultrasound during the last 10 years. We summarized the fetal ultrasound findings that led to the diagnosis and compared them with the autopsy results. RESULTS: All affected fetuses were diagnosed using detailed fetal ultrasound after 16 weeks' gestation. The main prenatal findings were omphalocele, skin-covered lumbosacral neural tube defect, non-visualized bladder and limb defects. Prenatal sonography failed to detect the abnormal genitalia, bladder exstrophy and anal atresia. All cases had abnormalities in a 'diaper distribution', which helped in making the prenatal diagnosis. Eight of the nine couples chose to terminate the pregnancies following multidisciplinary counseling. The pregnancy that was continued was a case with dizygotic twins discordant for OEIS, and the affected fetus died in utero. CONCLUSIONS: The combination of the following ultrasound findings: ventral wall defect, spinal defect and a non-visualized bladder with or without limb defects, are characteristic of OEIS complex. Diagnosis can be made with confidence as early as 16 weeks' gestation, although earlier diagnosis may be possible.

Abnormalities, Multiple↗
PubMed2006

A technique to identify and preserve the spinal accessory nerve during neck dissection.

INTRODUCTION: Preservation of the spinal accessory nerve during neck dissection should be the rule rather than the exception. Despite the presence of many described techniques to locate the nerve, a tedious dissection is often required; as a consequence, it remains vulnerable to damage. METHOD: We describe a novel method, not previously reported, based on identifying a constant vein which crosses the nerve. This aids in the nerve's early identification. CONCLUSION: Our method enables the surgeon to locate the nerve precisely and to avoid damage to it, thereby maximizing post-operative function.

Accessory Nerve↗
PubMed2001

Mice deficient in methylenetetrahydrofolate reductase exhibit hyperhomocysteinemia and decreased methylation capacity, with neuropathology and aortic lipid deposition.

Hyperhomocysteinemia, a risk factor for cardiovascular disease, is caused by nutritional and/or genetic disruptions in homocysteine metabolism. The most common genetic cause of hyperhomocysteinemia is the 677C-->T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene. This variant, with mild enzymatic deficiency, is associated with an increased risk for neural tube defects and pregnancy complications and with a decreased risk for colon cancer and leukemia. Although many studies have reported that this variant is also a risk factor for vascular disease, this area of investigation is still controversial. Severe MTHFR deficiency results in homocystinuria, an inborn error of metabolism with neurological and vascular complications. To investigate the in vivo pathogenetic mechanisms of MTHFR deficiency, we generated mice with a knockout of MTHFR: Plasma total homocysteine levels in heterozygous and homozygous knockout mice are 1.6- and 10-fold higher than those in wild-type littermates, respectively. Both heterozygous and homozygous knockouts have either significantly decreased S-adenosylmethionine levels or significantly increased S-adenosylhomocysteine levels, or both, with global DNA hypomethylation. The heterozygous knockout mice appear normal, whereas the homozygotes are smaller and show developmental retardation with cerebellar pathology. Abnormal lipid deposition in the proximal portion of the aorta was observed in older heterozygotes and homozygotes, alluding to an atherogenic effect of hyperhomocysteinemia in these mice.

Animals↗
PubMed2001

Contrast sensitivity following focal laser photocoagulation in clinically significant macular oedema due to diabetic retinopathy.

PURPOSE: To evaluate the influence of focal aser photocoagulation on contrast sensitivity in diabetic patients with clinically significant macular oedema (CSMO). METHODS: A prospective non-comparative interventional study was performed on a group of patients with CSMO at Dr Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, a tertiary eye care centre. Thirteen diabetc patients (14 eyes) with CSMO and no history of prior photocoagulation were recruited for this study. Direct focal photocoagulation of all leaking microaneurysms was performed using an argon green laser (514 nm). A contact lens was used as a slit lamp delivery system. Evaluation of the best corrected Snellen visual acuity, contrast senstivity, slit lamp biomicroscopy, macular status on direct ophthalmoscopy and fluorescein angiography was carried out 1 month and 3 months after laser photocoagulation. RESULTS: Following direct focal laser photocoagulation, focal CSMO resolved completely in all but one eye, 4-8 weeks later, as seen on slit lamp biomicroscopy and/or fluorescein angiography. Post-treatment, visual acuity remained stationary in eight eyes, improved by one line in three eyes, by two lines in two eyes and by three lines in one eye. The mean +/- SD pretreatment and post-treatment decimal visual acuities were 0.49+/-0.30 and 0.59+/-0.28, respectively. The mean +/- SD pre-laser contrast sensitivity score was 121.3+/-83.6, which increased significantly to a mean +/- SD of 151.6+/-80.5 fo lowing direct focal photocoagulation. CONCLUSION: Focal argon laser photocoagulation in CSMO in diabetics helps in improving the contrast sensitivity and stabilizes the visual acuity. The changes in contrast sensitivity and visual acuity are independent of each other.

Contrast Sensitivity↗
PubMed2000

Enhanced performance of expanded bed chromatography on rigid superporous adsorbent matrix.

Rigid spherical macroporous adsorbent beads with surface hydroxyl groups were prepared by cross-linking of cellulose. These beads had diameter in the range 100-200 microm and a mean pore size of about 3 microm with about 60% pore volume. The matrix (bulk density approximately 1600 kg m(-3)) could be expanded into a stable bed and used for protein chromatography. Chromatographic runs were performed on a 10 mm diameter column under non-retaining and retaining conditions on the prepared matrix (called Celbeads) and performance of the runs was measured in terms of the height equivalent to a theoretical plate (HETP). The HETP curves in both packed and expanded bed modes followed profiles typical of macroporous adsorbents, i.e. increasing and levelling with velocity. Unimpaired performance of the matrix at increasing flow-rates permitted expanded bed elution of adsorbed solutes without loss of efficiency in terms of purification factor and product concentration. As a model system, Celbeads was used to purify lactate dehydrogenase from porcine muscle homogenate by dye-affinity chromatography. The prepared matrix provided about 100 theoretical plates per meter for the enzyme system at a linear flow velocity of 1.27 cm x min(-1) in an expanded bed elution mode, and gave enzyme yields of 100% with a purification factor of 31 using an optimized procedure. The adsorbent could be cleaned in place with 5 M urea and used repeatedly without loss of performance.

Animals↗
PubMed1999

Expanded bed adsorption on supermacroporous cross-linked cellulose matrix.

Rigid spherical macroporous adsorbent beads (CELBEADS) prepared by cross-linking of cellulose were characterized and found eminently suitable for use as expanded bed affinity chromatography matrix. Chromatographic runs were performed on a 10 mm diameter column with three solutes tyrosine, papain and bovine serum albumin under non-retaining conditions on CELBEADS and Streamline DEAE, a commercial agarose based expanded bed matrix. Performance of the runs was measured in terms of height equivalent to theoretical plate, HETP. Variation in HETP with velocity on Streamline DEAE gave flat profiles in packed bed and increasing trend in expanded bed. On CELBEADS, the HETP curves in both packed and expanded bed modes followed profiles typical of macroporous adsorbents i.e. increasing and levelling with velocity. HETP values obtained for papain and bovine serum albumin on CELBEADS were lower than those obtained on Streamline DEAE at all velocities. Lactate dehydrogenase was purified from porcine muscle homogenate using Cibacron blue conjugated to CELBEADS using a protocol reported for supports with surface hydroxyl groups. Elution of the enzyme was investigated both in packed mode as well as in expanded mode at a flow rate of 1 ml min-1. The purification procedure took about 60 minutes and a purification fold of about 14 was achieved in both cases. The adsorbent could be cleaned in place with 5 M urea and used repeatedly without loss of performance.

Adsorption↗
PubMed1999

Antibiotics sensitivity pattern of N. gonorrhoeae with special emphasis on norfloxacin and ciprofloxacin.

The current study is carried out to find the in-vitro susceptibility of N. gonorrhoeae to Ciprofloxacin, Norfloxacin, Gentamycin etc. in 110 isolates obtained from acute gonococcal urethritis confirmed by smear examination. The isolates obtained are from the patients attending the Skin and STD Clinic of a teaching hospital, clinically diagnosed as suffering from acute gonococcal urethritis. Antibiotic susceptibility test was done by Kirby Bauer disc diffusion technique. Four to five similar well isolated colonies of the gonococcal strains were picked up with a wire loop and transferred to 5 cc of sterile trypticase soya broth (TSB). Tubes were incubated at 36 degrees C. GC agar base plates were inoculated with suspensions using a sterile cotton swab. Antibiotic discs were placed on these plates. The plates were incubated at 35 degrees C for 18-24 hours in a candle jar with 5-10% CO2. The plates were then observed to note the zones of inhibition around the discs. 87.27% of isolated strains were inhibited by norfloxacin at an MIC of 0.06 mu gm/ml; 89.08% of the strains were inhibited by ciprofloxacin at an MIC of 0.025 mu gm/ml. All the strains (110) were inhibited by ciprofloxacin at a concentration of 0.2 mu gm/ml. Gentamycin sensitivity was 86.36%. Out of 110 patients, 85 were treated with norfloxacin of which 81 (95.29%) were cured. Twenty five were treated with ciprofloxacin of which 24 (96%) were cured. This study shows high sensitivity of N. gonorrhoeae to norfloxacin and ciprofloxacin.

Adult↗
PubMed1998

Gene structure of human and mouse methylenetetrahydrofolate reductase (MTHFR)

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a co-substrate for homocysteine remethylation to methionine. A human cDNA for MTHFR, 2.2 kb in length, has been expressed and shown to result in a catalytically active enzyme of approximately 70 kDa. Fifteen mutations have been identified in the MTHFR gene: 14 rare mutations associated with severe enzymatic deficiency and 1 common variant associated with a milder deficiency. The common polymorphism has been implicated in three multifactorial diseases: occlusive vascular disease, neural tube defects, and colon cancer. The human gene has been mapped to chromosomal region 1p36.3 while the mouse gene has been localized to distal Chromosome (Chr) 4. Here we report the isolation and characterization of the human and mouse genes for MTHFR. A human genomic clone (17 kb) was found to contain the entire cDNA sequence of 2.2 kb; there were 11 exons ranging in size from 102 bp to 432 bp. Intron sizes ranged from 250 bp to 1.5 kb with one exception of 4.2 kb. The mouse genomic clones (19 kb) start 7 kb 5' exon 1 and extend to the end of the coding sequence. The mouse amino acid sequence is approximately 90% identical to the corresponding human sequence. The exon sizes, locations of intronic boundaries, and intron sizes are also quite similar between the two species. The availability of human genomic clones has been useful in designing primers for exon amplification and mutation detection. The mouse genomic clones will be helpful in designing constructs for gene targeting and generation of mouse models for MTHFR deficiency.

Amino Acid Sequence↗
PubMed1998

Triple procedure in posterior segment intraocular foreign body.

Three patients with intraocular foreign bodies and traumatic cataracts underwent single stage pars plana lensectomy with anterior capsule preservation, vitrectomy, removal of the foreign body, and intraocular lens implantation. The preserved anterior capsule permitted support for the placement of an intraocular lens in the posterior chamber in the ciliary sulcus. The procedure enabled early visual rehabilitation. This procedure seems useful in the management of posterior segment intraocular foreign body associated with cataract.

Adolescent↗
PubMed1997

Modified needle drainage of subretinal fluid for conventional scleral buckling procedures.

This study evaluated the efficacy and safety of a new technique used to drain subretinal fluid (SRF) during conventional scleral buckling procedures. The procedure was performed on 15 patients with primary rhegmatogenous retinal detachment in whom drainage of SRF was necessary during the surgery. It was successful in all but 1 case. The only significant complication was subretinal hemorrhage from the punctured choroid in 1 case, which resolved spontaneously without subsequent complications. This technique reduced the risk of complications during external SRF drainage, especially retinal and vitreous incarceration.

Body Fluids↗
PubMed1983

Use of cardiopulmonary bypass for thrombectomy in acute superior vena cava syndrome.

An increasing incidence of nonmalignant, indwelling catheter cases has been reported in relation to superior vena cava syndrome. Such cases may be life-threatening, with rapid development of facial and neck edema and the production of respiratory distress. This is the first reported case of atrial and superior vena caval thrombectomy requiring cardiopulmonary bypass; it is only the second case reported in which operative thrombectomy has been used. Because of the problems associated with an increase in the use of indwelling venous catheters and the satisfactory results we obtained in this case, such an aggressive form of treatment for acute, benign superior vena cava syndrome may be used more frequently in the future.

Journal Article↗
PubMedDate not supplied

Effect of adsorbent porosity on performance of expanded bed chromatography of proteins.

Expanded bed or fluidized bed adsorption has emerged as an important unit operation in downstream processing of proteins. A number of specifically designed commercial adsorbents are available today for expanded bed purification of proteins. Protein purification essentially requires adsorbent matrices that have large pore size. Very large pore size or macroporous adsorbents can provide high efficiency in packed beds even at high flow rates on account of reduced pore diffusion resistance resulting from finite intraparticle flow in the macropores. This is reflected in leveling off of HETP (height equivalent to theoretical plate) versus flow curve after a threshold velocity. Expanded bed operation, on the other hand, can also show plateauing of the HETP curve, but not necessarily on account of macroporosity of adsorbent. It is shown in this article how any adsorbent intended for protein adsorption in expanded bed mode can give plateauing HETP curve, regardless of pore size. As a result, RTD measurements on an expanded bed can give equal, and at times better, performance than a corresponding packed bed. Large pore size, on the other hand, can result in lesser retention of biomass and easy flushing of the adsorbent to obtain an entirely particulate-free adsorbent prior to the product elution step. Adsorbent with larger pores is also shown to provide faster and more efficient elution both in packed and expanded bed modes.

Adsorption↗
PubMedDate not supplied

AFLP-based genetic linkage map for the red flour beetle (Tribolium castaneum).

The red flour beetle (Tribolium castaneum) is a major pest of stored grain and grain products and a popular model species for a variety of ecological, evolutionary, and developmental biology studies. Development of a linkage map based on reproducible and highly polymorphic molecular markers would greatly facilitate research in these disciplines. We have developed a genetic linkage map using 269 amplified fragment length polymorphism (AFLP) markers. Ten previously known random amplified polymorphic DNA (RAPD) markers were used as anchor markers for linkage group assignment. The linkage map was constructed through genotyping two independent F(2) segregating populations with 48 AFLP primer combinations. Each primer combination generated an average of 4.6 AFLP markers eligible for linkage mapping. The length of the integrated map is 573 cM, giving an average marker resolution of 2.0 cM and an average physical distance per genetic distance of 350 kb/cM. A cluster of loci on linkage group 3 exhibited significant segregation distortion. We have also identified six X-linked and two Y-linked markers. Five mapped AFLP fragments were sequenced and converted to sequence-tagged site (STS) markers.

Animals↗