Search PubMed⌕ Search

Biomedical subjects

M E John

Publications and source records attributed to M E John.

At least 19 recordsLinked to original sources
PubMed2004

Post-partum practices among women in Calabar, Nigeria.

We carried out a study on post-partum practices amongst women in Calabar at the maternal and child health clinic at University of Calabar Teaching Hospital between 1 March and 31 May 2002. Three hundred women were interviewed. One hundred and ninety-three (64.3%) resumed coitus prior to 6 weeks of puerperium. There was no significant difference in parity (P = 0.20) and educational status (P = 0.10) between women who resumed coitus earlier than 6 weeks and those who resumed later. One out of every 10 women resumed coitus without any contraception. The majority [212 (70.7%)] sat in hot water (sitz bath) to aid perineal wound healing and improve vaginal tone.

Adult↗
PubMed1996

Metabolic pathway engineering in cotton: biosynthesis of polyhydroxybutyrate in fiber cells.

Alcaligenes eutrophus genes encoding the enzymes, beta-ketothiolase (phaA), acetoacetyl-CoA reductase (phaB), and polyhydroxyalkanoate synthase (phaC) catalyze the production of aliphatic polyester poly-d-(-)-3-hydroxybutyrate (PHB) from acetyl-CoA. PHB is a thermoplastic polymer that may modify fiber properties when synthesized in cotton. Endogenous beta-ketothiolase activity is present in cotton fibers. Hence cotton was transformed with engineered phaB and phaC genes by particle bombardment, and transgenic plants were selected based on marker gene, beta-glucuronidase (GUS), expression. Fibers of 10 transgenic plants expressed phaB gene, while eight plants expressed both phaB and phaC genes. Electron microscopy examination of fibers expressing both genes indicated the presence of electron-lucent granules in the cytoplasm. High pressure liquid chromatography, gas chromatography, and mass spectrometry evidence suggested that the new polymer produced in transgenic fibers is PHB. Sixty-six percent of the PHB in fibers is in the molecular mass range of 0.6 x 10(6) to 1.8 x 10(6) Da. The presence of PHB granules in transgenic fibers resulted in measurable changes of thermal properties. The fibers exhibited better insulating characteristics. The rate of heat uptake and cooling was slower in transgenic fibers, resulting in higher heat capacity. These data show that metabolic pathway engineering in cotton may enhance fiber properties by incorporating new traits from other genetic sources. This is an important step toward producing new generation fibers for the textile industry.

Journal Article↗
PubMed1996

Structural characterization of genes corresponding to cotton fiber mRNA, E6: reduced E6 protein in transgenic plants by antisense gene.

Two genes, each corresponding to fiber mRNA E6, were isolated from cotton cultivars Coker 312 (Gossypium hirsutum L.) and Sea Island (G. barbadense L.). E6 is one of the predominant fiber-specific mRNAs present during early fiber development. The distinguishing feature of nucleotide-derived E6 protein is the presence of a motif where a dimer, Ser-Gly, is repeated several times. Two of the Sea Island genes contained a pentameric motif, Ser-Gly, while one of the Coker genes had one and the other had four motifs each. cDNA clones containing one or five Ser-Gly motifs were also identified. Thus, it appears that the strict conservation of this motif may not be critical to E6 protein function. Sequence characterizations of the genes and cDNAs showed that multiple members of the E6 family are transcribed in fiber and may result in proteins 238 to 246 amino acids long. The 3' ends of the genes and cDNAs showed considerable heterology among them. Transgenic plants containing antisense genes were generated to decipher E6 function. Transgenic cotton with reduced E6 protein levels in the range of 60 to 98% were identified. However, no discernible phenotypic changes in fiber development or properties were apparent. This result leads to the conclusion that E6 is not critical to the normal development or structural integrity of cotton fibers.

Amino Acid Sequence↗
PubMed1996

Photorefractive keratectomy for residual myopia after radial keratotomy.

PURPOSE: To evaluate the results of photorefractive keratectomy (PRK) to treat undercorrected radial keratotomy (RK). SETTING: Instituto de Oftalmologia Tadeu Cvintal, São Paulo, Brazil. METHODS: A consecutive series of 28 eyes that had PRK to treat residual myopia after RK were studied. Refractive visual and safety data were collected and evaluated. RESULTS: One year after PRK, 75% of eyes had an uncorrected visual acuity of 20/25 or better and 85%, 20/40 or better. All but one case maintained or improved best corrected visual acuity; one case decreased from 20/25 to 20/30. At 1 year, 75% of eyes were within 0.50 diopter (D) of emmetropia and 90% were within 1.00 D. Only one case was more than 1.00 D undercorrected (-1.125 D) at 1 year. Mean pre-RK myopia was -5.90 D (range -2.00 to 11.80 D). Mean spherical equivalent improved from the residual postoperative level of -2.71 D +/- 0.86 (SD) before PRK to -0.21 +/- 0.86 D 1 to 3 months after PRK and to -0.40 +/- 0.43 D 1 year after PRK. CONCLUSION: Photorefractive keratectomy was efficacious in correcting residual myopia after RK in a group of selected patients.

Cohort Studies↗
PubMed1996

Tissue-specific and developmental regulation of cotton gene FbL2A. Demonstration of promoter activity in transgenic plants.

A gene (FbL2A) that is preferentially expressed in cotton (Gossypium barbadense L. cv Sea Island) fiber was isolated and characterized. Genomic and cDNA analyses suggest multiple FbL2A genes in cotton. The gene is developmentally regulated and is activated during late primary and early secondary wall synthesis stages. FbL2A encodes a polypeptide of 43.4 kD and a predicted isoelectric point of 5.97. The nucleotide-derived protein is highly hydrophilic except for a hydrophobic N terminus and has a compositional bias for glutamic acid (26.3 mol%) and lysine (18.9 mol%). Sixty-two percent of the putative protein is composed of repeat motifs. A 55-amino-acid peptide region is repeated four times in a concatenate fashion within the protein. The function of the protein in the fiber cells is not known. A 2.3-kb DNA fragment 5' from the FbL2A gene is shown to direct expression of heterologous proteins in transgenic cotton in a fiber-specific and developmentally regulated fashion. The FbL2A promoter was used to express in transgenic cotton genes encoding acetoacetyl-coenzyme A reductase and polyhydroxyalkanoic acid synthase, which are involved in the synthesis of the thermoplastic polymer polyhydroxybutyric acid. Transgenic plants containing both enzymes produced polyhydroxybutyric acid in fiber. Thus, the FbL2A promoter is useful in genetic engineering schemes to modify cotton fiber.

Amino Acid Sequence↗
PubMed1996

The Martines enhancement technique for correcting residual myopia following laser assisted in situ keratomileusis.

BACKGROUND AND OBJECTIVE: Laser assisted in situ keratomileusis (LASIK) is highly effective for correcting moderate to severe levels of myopia with rapid visual recovery, minimal pain and easier post-operative management compared with Photorefractive keratectomy. Nevertheless, undercorrection may occur. The purpose of this paper is to evaluate 14 undercorrected LASIK cases in which the cap was dissected and the stromal bed re-ablated using a method developed by one of the authors (EM). PATIENTS AND METHODS: Among a series of 297 LASIK procedures, visual and refractive results of 14 cases undergoing enhancement were evaluated. All cases were targeted for plano refraction. RESULTS: All 14 cases were followed at least 6 months and 7 (50%) have been followed two years. Mean pre-LASIK myopia of -14.60 +/- 4.90 D had been reduced to a mean of -4.50 +/- 2.60 D prior to enhancement. Following enhancement mean spherical equivalent was -0.22 D at 6 months. Results were stable at two years. All cases were within 1.25 D of target and 11 of 14 were within one diopter. Uncorrected vision was improved in all cases. Best corrected vision was maintained or improved in all but one case. This case had a decentered ablation. CONCLUSION: Laser enhancement of undercorrected LASIK cases using the Martines Technique was predictable and efficacious.

Adult↗
PubMed1995

Characterization of mRNA for a proline-rich protein of cotton fiber.

Cotton (Gossypium hirsutum L.) mRNA (H6) is expressed predominantly in fiber cells and is present during early primary cell wall formation. However, H6 protein is found to accumulate during later stages, when active secondary cell wall formation occurs, indicating possible regulation at the translational level and function in the secondary cell wall assembly. The nucleotide-derived amino acid sequence of pCK-H6 is proline rich (35 mol %) with a calculated molecular mass of 21 kD. Cotton protein H6 contains a repetitive pentameric motif (17) of alanine (serine)-threonine (serine)-proline-proline-proline. Its amino acid composition and solubility indicate that it may belong to the group of arabinogalactan proteins. Both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (55 kD) and size-exclusion chromatography (77-83 kD) overestimated the size of in vitro synthesized H6 protein compared to the molecular mass derived from the nucleotide sequence (21 kD). The conformation of the molecule determined by its unusual primary structure may be the cause of its anomalous mobility. The presence of a proline-rich, arabinogalactan-type protein in cotton fiber raises the interesting possibility that it may be an integral part of the plasmalemma taking part in the development and architecture of the secondary wall of cotton fiber.

Amino Acid Sequence↗
PubMed1994

Cotton (Gossypium hirsutum L.) pollen-specific polygalacturonase mRNA: tissue and temporal specificity of its promoter in transgenic tobacco.

A gene (G9) expressed during late microsporogenesis in cotton (Gossypium hirsutum L.) was isolated. Sequence analysis of the cDNA (1.3 kb) as well as the gene (2.6 kb) revealed an open reading frame of 1233 bases encoding a protein of 43.9 kDa. The coding region of the gene is interrupted by three introns. Northern analysis of the RNA from developing anthers showed that the transcripts appear 12 days before anthesis and that the maximal concentration of RNA occurs in pollen on the day of anthesis. This pattern of gene expression suggests functions in post-anthesis events. Sequence comparisons with other known plant genes indicated that G9 is homologous to polygalacturonases. The G9 promoter conferred tissue and temporal specificity of beta-glucuronidase (GUS) expression in transgenic tobacco plants. Thus, the G9 promoter can be used to drive gene expression in homologous as well as heterologous plants in a tissue-specific manner.

Amino Acid Sequence↗
PubMed1994

Excimer laser phototherapeutic keratectomy for treatment of recurrent corneal erosion.

Two patients with a history of frequent recurrent corneal erosion for whom standard medical therapy was determined ineffective had phototherapeutic keratectomy (PTK) with an excimer laser. Before treatment, one patient had four episodes in a six-month period; the other had ten to 20 recurrences with four serious episodes in a seven-month period. After PTK, neither patient had a recurrence after 18 months follow-up. Subjectively, both patients felt the treated area healed faster than previous abrasions. Vision, refraction, keratometry, and corneal thickness measurements appeared unaffected by the treatment.

Adult↗
PubMed1994

Clear lens extraction and intraocular lens implantation in a patient with bilateral anterior lenticonus secondary to Alport's syndrome.

We describe bilateral phacoemulsification and implantation of foldable silicone intraocular lenses in a 25-year-old woman with Alport's syndrome and severe anterior lenticonus. Contrary to previous reports of lens capsule fragility in Alport's syndrome, this patient had relatively tough capsules, as do most patients her age. Apart from the tough capsules and positive pressure, which required the use of a viscoelastic to maintain the anterior chamber, the surgeries were unremarkable. The patient achieved excellent visual and refractive results.

Adult↗
PubMed1992

Gene expression in cotton (Gossypium hirsutum L.) fiber: cloning of the mRNAs.

Cotton, an important natural fiber, is a differentiated epidermal cell. The number of genes that are active in fiber cells is similar to those in leaf, ovule, or root tissues. Through differential screening of a fiber cDNA library, we isolated five cDNA clones that are preferentially expressed in fiber. One of the cDNA clones, pCKE6, corresponded to an abundant mRNA in fiber. Transcripts for E6 were detected throughout the development of the fiber. Immunoprecipitation of in vitro translation products and Western blot analysis of fiber proteins showed two polypeptides in the range of 30-32 kDa as the products of E6 mRNA. Sequence analysis and hybrid-selected RNA translation also suggest that E6 mRNAs encode two polypeptides. Concentrations of E6 mRNA and protein are highest during the late primary cell wall and early secondary cell wall synthesis stages. Sequence comparison of E6 with other known eukaryotic and prokaryotic genes reveals no significant homology (GenBank; December 1991). E6 or a homologous gene(s) is conserved in several members of Malvaceae as well as in one other fiber-producing plant, kapok, but is not found in several other plants examined or in Acetobacter xylinum. A genomic clone corresponding to pCKE6 was isolated, and the promoter element of the E6 gene was shown to direct the expression of a carrot extensin mRNA in a tissue-specific and developmentally regulated fashion in transgenic cotton plants.

Amino Acid Sequence↗
PubMed1992

Characterization of a stress-induced, developmentally regulated gene family from soybean.

We describe a family of stress-induced, developmentally regulated soybean genes for which cDNAs have been obtained from two different cultivars (Glycine max cv. Mandarin and Glycine max cv. Williams). The mRNAs corresponding to these cDNAs, called SAM22 and H4, respectively, accumulate predominantly in the roots of soybean seedlings but are present at high levels in the roots and leaves of mature plants. SAM22 accumulation is especially dramatic in senescent leaves. In addition, SAM22 accumulation can be induced on young leaves by wounding or by transpiration-mediated uptake of salicylic acid, methyl viologen, fungal elicitor, hydrogen peroxide or sodium phosphate (pH 6.9). Taken together, these data indicate that the genes corresponding to SAM22 and H4 are induced by various stresses and developmental cues. Southern blot analysis indicates that multiple copies of sequences related to SAM22 exist in the soybean genome. We also show that the nucleotide sequences of the cDNAs corresponding to SAM22 and H4 are 86% identical at the nucleotide level to each other and 70% identical at the amino acid level to the 'disease resistance response proteins' of Pisum sativum.

Amino Acid Sequence↗