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Biomedical subjects

A Jacob

Publications and source records attributed to A Jacob.

At least 37 records · Page 2Linked to original sources
PubMed1998

Recovery of spermatogenesis following bone marrow transplantation.

Preparative regimens used in bone marrow transplantation usually result in impairment of male fertility. Although recovery of fertility is more likely after chemotherapy-based regimens, this is a rare occurrence after TBI containing regimens. We undertook a cross-sectional study of recovery of spermatogenesis in men who had undergone allogeneic and autologous marrow or peripheral stem cell transplant between 1984 and 1995. We identified six out of 42 patients eligible for analysis to have either recovered fertility or spermatogenesis. Seminal fluid analysis showed that four out of 25 patients recovered sperm counts. This has important implications for patient counselling, post-transplant follow-up and contraceptive advice.

Adult↗
PubMed1998

Human sperm non-nuclear progesterone receptor expression is a novel marker for fertilization outcome.

In a prospective, blind study, we have examined the relationship among the expression of human sperm surface progesterone receptors, the ability to undergo a mannose-stimulated acrosome reaction and the rate of fertilization in vitro. Individual aliquots of motile spermatozoa were surface-labelled with progesterone and/or mannose-fluoresceinated ligands. Spontaneous acrosome loss and the increase in acrosome reactions following exposure of spermatozoa to mannose ligands were assessed using rhodaminated Pisum sativum agglutinin. Progesterone fluoresceinated ligand binding was observed to occur in two patterns: (i) a uniform distribution of labelling over the acrosome cap (pattern II), and (ii) labelling limited to the equatorial and postacrosomal regions of the human sperm head (pattern III). A conversion of pattern II to pattern III binding was observed and was associated with the acrosome reaction. Pattern III binding was highly correlated with both fertilization potential and the ability to undergo a mannose-stimulated acrosome reaction (P < 0.001). In contrast, normal sperm mannose receptor expression was seen in five men whose abnormal progesterone receptor expression/function and inability to acrosome react after mannose treatment were correlated with their reduced fertility in vitro. In conclusion, surface progesterone receptor aggregation enhances the mannose ligand-stimulated acrosome reaction. Such detection of defective sperm surface progesterone receptor expression/function may be useful in the evaluation and management of male infertility.

Acrosome↗
PubMed1998

Bilateral simultaneous hearing preservation mastoidectomy in otogenic meningitis.

Bilateral simultaneous hearing conservation mastoidectomy has not been previously documented. We present our experience with this procedure. Three patients with pyogenic meningitis secondary to bilateral unsafe ears had hearing preservation surgeries of both ears in a single sitting. Although ear surgery carries risk of inner ear damage, in our series there was no deterioration of inner ear function in the 6 ears operated on. The air conduction threshold improved in 3 (50%) of the ears. When meningitis results from bilateral otogenic foci as in our series, simultaneous mastoidectomy in both ears may be the preferred method of treatment to eradicate the source of infection.

Adult↗
PubMed1998

Prevalence of primary glaucoma in an urban south Indian population.

Glaucoma is fast emerging as a major cause of blindness in India. In order to estimate the prevalence of primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) in an urban South Indian population, we examined 972 individuals aged 30-60 years, chosen using a cluster sampling technique from 12 census blocks of Vellore town. They underwent a complete ocular examination, including applanation tonometry and gonioscopy, at the Medical College Hospital. Characteristic field defects on automated perimetry was a diagnostic requisite for POAG. Prevalence (95% CI) of POAG, PACG, and ocular hypertension were 4.1 (0.08-8.1), 43.2 (30.14-56.3), and 30.8 (19.8-41.9) per 1,000, respectively. All the PACG cases detected were of the chronic type. Hitherto unavailable community-based information on primary glaucoma in our study population indicates that PACG is about five times as common as POAG.

Adult↗
PubMed1998

Modified preparation and rapid quality control test for technetium-99m-tetrofosmin.

OBJECTIVE: The objectives of this study were to: modify the preparation of 99mTc-tetrofosmin by using twice the amount of 99mTcO4- recommended by the manufacturer; evaluate the use of miniaturized rapid paper chromatography (MRPC) for quality control (QC) testing; and determine the in vitro stability of the modified preparation using MRPC. METHODS: Two preparations of 99mTc-tetrofosmin were made: one with 4.4-8.8 GBq (120-240 mCi) and the other with 13.9-17.6 GBq (380-480 mCi) 99mTcO4-, referred to as regular and modified preparations, respectively. Routine QC tests were performed using MRPC and instant thin-layer chromatography/silica-gel (ITLC/SG) systems. The preparations were injected into 58 patients. Planar and SPECT images of stress and rest studies were obtained. The technical quality of the SPECT images was graded visually by four observers. Heart-to-lung and heart-to-background ratios were calculated from the planar images. RESULTS: The QC testing procedure took 4.18 +/- 0.15 min with MRPC and 54 +/- 5.3 min with ITLC/SG systems. The percent labeling efficiency, as determined by both techniques, ranged from 95.6 +/- 1.6 to 97.2% +/- 0.8%. Both preparations were stable up to 6 hr after reconstitution. There was no difference between the cardiac-to-lung and cardiac-to-background ratios of the two preparations. CONCLUSION: The results indicate that MRPC is a faster and effective chromatographic technique for routine QC testing of 99mTc-tetrofosmin. Doubling the amount of 99mTcO4- used in preparing 99mTc-tetrofosmin did not affect its in vitro stability, its efficacious use in patients or the technical quality of the images.

Chromatography, Paper↗
PubMed1997

Differential induction of HNF-3 transcription factors during neuronal differentiation.

We have investigated the regulation of transcription factors HNF-3alpha and HNF-3beta during the retinoic acid-mediated differentiation of mouse P19 cells. Retinoic acid treatment converts P19 stem cells into neurons and astrocytes and we have clearly shown that gene expression of both HNF-3alpha and HNF-3beta is activated during this process. HNF-3alpha transcription was detected 2 h after addition of retinoic acid and took place in the absence of de novo protein synthesis. This suggests that HNF-3alpha is a primary target for retinoic acid action. HNF-3alpha induction displays a biphasic profile and HNF-3alpha mRNA reaches maximal levels at 2 and 6 days postdifferentiation. Additional experiments strongly suggest that the second peak is due to HNF-3alpha induction in postmitotic neurons. P19 stem cells, on the other hand, do not contain any detectable HNF-3alpha mRNA. According to our studies, the retinoic acid-mediated induction of HNF-3alpha occurs at the level of transcriptional initiation and is conferred by distal promoter sequences. In comparison to HNF-3alpha, HNF-3beta induction is a subsequent event and detectable levels of HNF-3beta mRNA materialize approximately 1 day after addition of retinoic acid to P19 stem cells. Time course studies firmly demonstrate that HNF-3beta mRNA peaks at about 2 days postdifferentiation and then declines to virtually unreadable levels. This temporal pattern is consistent with HNF-3beta being a secondary target for retinoic acid. In analogy to HNF-3alpha, HNF-3beta activation also takes place at the level of transcriptional initiation. Recent studies implicate HNF-3alpha and HNF-3beta in early mammalian neurogenesis. The detection of HNF-3alpha/beta activation during P19 cell differentiation provides us with a convenient cell culture system to elucidate the induction mechanism and the precise role of both transcriptional regulators in the formation of neuronal cells.

Animals↗
PubMed1997

Hearing impairment and otitis media in a rural primary school in south India.

In order to determine the prevalence of hearing impairment and otitis media in rural primary school children, a pilot study of 284 children aged 6-10 years was performed. These children were screened by otoscopy, pure tone audiometry and tympanometry. The overall prevalence of otological abnormalities (excluding wax) was 21.5%. Hearing impairment was detected in 34 children (11.9%). Conductive hearing impairment was predominant (10.9%). Otitis media was diagnosed in 17.6% of children. While 91.2% of children with hearing impairment had associated middle ear disease, only 53.4% of those with middle ear disease were detected as have hearing impairment. The importance of including tympanometry as part of the screening protocol is highlighted.

Acoustic Impedance Tests↗
PubMed1997

Recovery of nucleic acids from immobilized biotin-streptavidin complexes using ammonium hydroxide and applications in MALDI-TOF mass spectrometry.

The effects of ammonium hydroxide treatment of complexes consisting of biotinylated nucleic acids and immobilized streptavidin were investigated. It was found that incubation of such complexes with ammonium hydroxide at room temperature leads to denaturation of double-stranded DNA molecules, liberating only the complementary nonbiotinylated strand, whereas incubation at elevated temperatures leads to an efficient dissociation of biotin-streptavidin complexes. The introduced procedure is especially suitable as a purification and conditioning format prior to matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometric analysis of DNA from complex enzymatic reactions. This is demonstrated by analysis of polymerase chain reaction (PCR) and sequencing products.

Ammonium Hydroxide↗
PubMed1997

Saphenous vein covered stenting for right coronary artery lesion containing thrombus.

Vein covered stenting to close coronary pseudoaneurysm and perforation and in the setting of acute myocardial infarction have been described. This case report describes saphenous vein covered stenting to exclude a large thrombus in a right coronary artery lesion. Vein covered stenting may be considered as an option when dealing with a thrombus containing lesion.

Aneurysm, False↗
PubMed1997

Dyspnea after pneumonectomy: the result of an atrial septal defect.

We report the case of severe hypoxemia attributable to right-to-left shunting through an atrial septal defect after right-sided pneumonectomy that developed in a 70-year-old man. Normal right atrial and pulmonary artery pressures were measured. Right-to-left shunting through a patent foramen ovale is known as a rare complication after pneumonectomy. Our patient, however, demonstrated a true atrial septal defect (septum secundum defect) upon open operative repair of the interatrial connection.

Aged↗
PubMed1997

t(3;21) following peripheral blood stem cell transplantation in chronic phase chronic myeloid leukaemia.

A 40-year-old male with Ph-positive CML underwent PBSC autografting after initial treatment with hydroxyurea and interferon. Following autograft he remained in chronic phase with cytogenetic or molecular evidence of low levels of residual Ph-positive cells. However, additional cytogenetic abnormalities, including t(3;21) typically seen in therapy-related myelodysplastic syndrome (MDS) and AML and blast crisis of CML, developed as an independent cell line following the autograft. More than 4 years after the autograft, the patient remains in chronic phase with no evidence of accelerated phase or blast crisis of CML, but with a concurrent MDS. We report a case of CML who developed therapy-related MDS following PBSC autograft while still remaining in chronic phase.

Adult↗
PubMed1997

Use of mannose ligands in IVF screens to mimic zona pellucida-induced acrosome reactions and predict fertilization success.

A predictive test for determining whether motile populations of human spermatozoa will fertilize eggs in vitro has been an elusive goal of clinical research. We have developed an assay for the ability of motile human spermatozoa to bind fluorescein isothiocyanate-labelled mannosylated bovine serum albumin (Man-FITC-BSA) as a test for the presence of sperm surface receptors (lectins) for mannose ligands. Mannosylated ligands are present on the human zona pellucida and are involved in the species-specific binding of human spermatozoa to the zona pellucida. We now demonstrate in prospective blinded analysis that the fractional increase in acrosome loss following a mannose ligand challenge is highly correlated with the rate of fertilization in vitro. Using an incremental increase of acrosome exocytosis of >0.1 as a threshold to predict which specimens will yield normal fertilization, the assay has a sensitivity of 97.8%, a specificity of 83.3%, a positive predictive value of 95.7% and a negative predictive value of 90.7%. These data indicate that testing for a mannose-induced acrosome reaction may be useful in assessment of sperm function prior to in-vitro fertilization in order to assign males to conventional insemination or intracytoplasmic sperm injection protocols.

Acrosome↗
PubMed1997

Visual outcome and complications of residents learning phacoemulsification.

The increasing popularity of phacoemulsification in our country raises important training issues. We prospectively analyzed the incidence of complications and visual outcomes in the initial 70 phacoemulsifications (70 patients) performed by the first two residents learning phacoemulsification in our training programme. Both were experienced in standard (manual) extracapsular cataract extraction. Postoperative follow up of 6 weeks or longer was available in 59 eyes. The 11 patients (11 eyes) lost to follow up did not have any intra-operative complications. The overall incidence of vitreous loss was 10%, similar to the frequency of this complication (determined retrospectively) in the first 70 standard extracapsular cataract extractions performed by the same residents. Intraocular lenses (IOL) were successfully implanted in 62 eyes, as planned. One IOL dislocated into the vitreous was successfully repositioned. Other complications encountered included superior corneal edema (3 eyes), iris damage inferiorly (7 eyes) and clinical cystoid macular edema (5 eyes). A best corrected visual acuity of 6/12 or better was obtained in 56 (94.8%) of the 59 eyes available for the six week follow up. In the eyes with vitreous loss, 6 out of 7 had visual acuity better than 6/12. No nuclei were lost into the vitreous. The rate of surgical complications for residents learning phacoemulsification in a supervised manner can be acceptably low.

Clinical Competence↗
PubMed1996

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the detection of polymerase chain reaction products containing 7-deazapurine moieties.

Double-stranded DNA fragments of different length with and without the incorporation of 7-deazapurine deoxynucleotides have been prepared via the polymerase chain reaction (PCR) using exo(-)Pseudococcus furiosus DNA polymerase, unmodified primers, and c7-dATP and c7-dGTP as the only purine triphosphates. In spite of the presence of some unmodified purine moieties due to the primers, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry revealed remarkable differences between the modified and unmodified DNA fragments. The incorporation of 7-deazapurine nucleotides resulted in a significant reduction of fragmentation and therefore in increased signal intensities and higher mass resolution. The molecular weights could be determined with an accuracy of up to 0.03%. Mass resolution was sufficient to resolve the (M + H)+ signals of the two single strands of a 7-deazapurine-containing 99-base-pair DNA duplex. Thus, MALDI-TOF mass spectrometry offers a very fast and accurate way to detect and analyze short PCR products sufficient in length for many diagnostic applications without gel electrophoresis and labeling.

Autoradiography↗
PubMed1996

Analysis of ligase chain reaction products via matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry.

A rapid and accurate detection of ligation products generated in ligase chain reactions (LCR) by using matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-TOF-MS) is reported. LCR with Pfu DNA ligase was performed with a wild-type template and a template carrying a single point mutation within the Escherichia coli lacI gene as a model system. Starting from about 1 fmol of template DNA the ligation product generated in the positive reactions was analyzed with HPLC and MALDI-TOF-MS, whereby the need of proper sample purification prior to mass spectrometric analysis was demonstrated. A purification procedure with a high potential for automation using streptavidin-coated magnetic particles and ultrafiltration was introduced. Plasmid DNA and short single-stranded oligonucleotides have been used as template. A point mutation could be discriminated from the wild-type template due to the absence or presence of ligation product. This approach allows the rapid-specific detection of template DNA in femtomole amounts and moreover can distinguish between sequence variations in DNA molecules down to point mutations without the need for labeling, gel electrophoresis, membrane transfer, or hybridization procedures.

Base Sequence↗
PubMed1996

Detection of hepatitis B virus DNA in serum samples via nested PCR and MALDI-TOF mass spectrometry.

In a blind study, nested polymerase chain reaction (PCR) was performed with control DNA and DNA preparations from serum samples of six patients. The detection limit was determined to be 100 molecules of template in 1 ml of serum. Hepatitis B virus (HBV) related products of nested PCR were purified by ultrafiltration and immobilisation on streptavidin coated magnetic beads. The immobilized PCR products were denatured from the beads and analyzed via matrix assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry. The results of MALDI-TOF MS analysis were in agreement with the results obtained by polyacrylamide gel electrophoresis (PAGE) and with the data obtained by serological analysis. The detection strategy introduced here has a high potential for automation and represents a fast and reliable method of detection for HBV DNA in serum without the need for time consuming gel electrophoresis and labeling or hybridization procedures.

DNA, Viral↗