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Biomedical subjects

R J Sharp

Publications and source records attributed to R J Sharp.

At least 37 records · Page 2Linked to original sources
PubMed1997

Survival after necrotizing enterocolitis in infants weighing less than 1,000 g: 25 years' experience at a single institution.

Necrotizing enterocolitis (NEC) primarily affects premature newborns. Regional and national decreases in the mean birthweight and gestational age of neonatal intensive care unit (NICU) admissions prompted a review of NEC in VLBW (very low birth weight, defined as < 1,000 g) infants in our institution over a 25-year period. There were 266 patients treated for NEC during the study interval. We compared 71 VLBW with 195 non-VLBW infants and found that VLBW infants were: fed later (6.4 days v 4.1 days, P = .009), developed NEC later (20.8 days v 13.1 days, P = .002), had significantly lower 1- and 5-minute Apgar scores, were more likely to require surgery (51% v 34%, P = .016), more often had panintestinal (defined as > 75% of intestinal length) involvement (10% v 4%, P = .043), and had poorer survival (56% v 72%, P = .013). Overall survival after NEC has improved over the study interval, both in our series and in other reports. However, the increasing number of VLBW infants who have NEC represent a subgroup who appear to be generally more ill, develop NEC later, require surgery with greater frequency than their non-VLBW counterparts, and are less likely to survive.

Age of Onset↗
PubMed1997

Degradation of 3-chlorobenzoate by thermophilic micro-organisms.

Thermophilic (75 degrees C), anaerobic biodegradation of chlorobenzoates was investigated using different inocula from geothermal and non-geothermal environments. Microbial dehalogenation of 3-chlorobenzoate (0.5 mmol l-1 was achieved by two mixed cultures growing anaerobically at 75 degrees C. One culture consisted of a facultative anaerobe and two obligate anaerobes, one of which was a methanogen, isolated from terrestrial sediments from hot springs in New Zealand. The other culture, derived from a non-geothermal environment, consisted of a Clostridium spp. and a non-spore-forming obligate anaerobe. No degradation of either 2-chlorobenzoate or 4-chlorobenzoate was achieved by these thermophilic cultures over the same time period. This is the first reported biotransformation of this chlorinated aromatic at a temperature of 75 degrees C.

Bacteria↗
PubMed1997

Stabilization of Enzymes against Thermal Stress and Freeze-Drying by Mannosylglycerate.

2-O-(beta)-Mannosylglycerate, a solute that accumulates in some (hyper)thermophilic organisms, was purified from Pyrococcus furiosus cells, and its effect on enzyme stabilization in vitro was assessed. Enzymes from hyperthermophilic, thermophilic, and mesophilic sources were examined. The thermostabilities of alcohol dehydrogenases from P. furiosus and Bacillus stearothermophilus and of glutamate dehydrogenases from Thermotoga maritima and Clostridium difficile were improved to a significant extent when enzyme solutions were incubated at supraoptimal temperatures in the presence of 2-O-(beta)-mannosylglycerate, but no effect on the thermostability of glutamate dehydrogenase from P. furiosus was detected. On the other hand, there was a remarkable effect on the thermal stabilities of rabbit muscle lactate dehydrogenase, baker's yeast alcohol dehydrogenase, and bovine liver glutamate dehydrogenase, which were used as model systems to evaluate stabilization of enzymes of mesophilic origin. For all of the enzymes examined and at the highest temperatures tested, 2-O-(beta)-mannosylglycerate was a better thermoprotectant than trehalose. The stabilizing effect exerted by 2-O-(beta)-mannosylglycerate on enzymes suggests a role for this compound as a protein thermostabilizer under physiological conditions. 2-O-(beta)-Mannosylglycerate was also effective in the protection of enzymes against stress imposed by freeze-drying, with its protecting effect being similar to or better than that exerted by trehalose. The data show 2-O-(beta)-mannosylglycerate to be a potential enzyme stabilizer in biotechnological applications.

Journal Article↗
PubMed1996

Thal fundoplication in neurologically impaired children.

Children with neurological impairment (NI) frequently require feeding gastrostomy, and this often aggravates or produces gastroesophageal reflux (GER). From 1976 to 1994, 141 children with severe NI underwent Thal fundoplication and gastrostomy (GT). GER was evident in 80%; in the rest, fundoplication was an adjunct to GT. Ph results were positive in 38 cases, and 57 children had reflux according to the barium studies. There were no major intraoperative complications. Disruption of the repair and/or recurrent GER was noted in 14 cases (10%); 8 were redone as Thals, and 6 were converted to Nissen procedures. Pyloroplasty was done later in 9 children (6%). Bowel obstruction was seen in 4 patients (3%). Clinical follow-up (mean, 54 months) showed improvement in 96%; only 5 of the 141 (3.2%) have residual symptoms. Of the patients with an intact Thal, 67% could burp or vomit. The ability to vomit may protect the Thal fundoplication and avoid disruption of the repair.

Adolescent↗
PubMed1995

DNA relatedness of Thermus strains, description of Thermus brockianus sp. nov., and proposal to reestablish Thermus thermophilus (Oshima and Imahori)

Aerobic, thermophilic, gram-negative bacteria obtained from Yellowstone National Park that were placed in the genus Thermus on the basis of phenotypic data were examined by chemotaxonomic techniques to determine their peptidoglycan compositions, their respiratory quinones, their mean DNA base compositions, and their levels of DNA-DNA homology as determined by both the filter hybridization and reassociation rate methods. These isolates from hot springs included Thermus aquaticus strains and strains of a new genospecies. We propose the name Thermus brockianus for this new genospecies; strain YS38 is the type strain of this taxon. A collection of 10 strains, including the type strain of "Thermus thermophilus", which were isolated from widely separated geothermal sites, exhibited high levels of DNA-DNA homology with each other and had similar physiological properties. Therefore, we propose that the species Thermus thermophilus (Oshima and Imahori) should be reestablished, with strain HB8 as the type strain.

Base Composition↗
PubMed1995

Factors affecting the electroporation of Bacillus subtilis.

Bacillus subtilis 168 trp- was found to be transformable with the tetracycline resistance plasmid pAB124 by electroporation of whole cells, inconsistently and at very low frequencies. Supplementation of the growth medium with glycine, or particularly DL-threonine, produced cells that could be electrotransformed much more efficiently at frequencies up to 2.5 x 10(3) transformants per microgram plasmid DNA. Transformation was optimal with cells grown in medium containing a racemic mixture of the D- and L-isomers of threonine, and no transformants were obtained when pure forms of the D- and L-threonine isomers were used. The cell walls of B. subtilis grown in the presence or absence of D-, L- and DL-threonine had a similar amino acid composition which did not include threonine. A more complex biochemical explanation of the enhancement of electroporation by growth in DL-threonine is likely, and this is discussed. Lysozyme treatments to weaken the cell wall and possibly mimic the effect of DL-threonine did not yield any transformants. The effects of buffer composition and culture incubation time were also determined and the electroporation protocol optimized accordingly. The response of a range of other B. subtilis strains to electroporation by the method produced was found to be variable. In all cases, transformation was verified by recovery of the plasmid DNA from putative transformants.

Amino Acids↗
PubMed1991

Relief of subglottic stenosis by anterior cricoid resection: an operation for the difficult case.

Anterior cricoid resection is an effective procedure to relieve subglottic stenosis. This is well documented in adults, although reports of the procedure in growing airways are limited. Over an 11-year period, seven pediatric patients underwent anterior cricoid resection for recalcitrant subglottic stenosis. In four patients, the stricture was secondary to prolonged intubation, one developed subglottic stenosis following a high placement of tracheostomy for epiglottitis and another had congenital subglottic stenosis. One child had subglottic stenosis combined with laryngotracheoesophageal cleft and more distally located tracheoesophageal fistula. All patients had failed to respond to previous treatment: dilatations (3 to 20), steroid injection (3 patients), and Evan's tracheoplasty (2 patients). All patients had an excellent result from anterior cricoid resection. The median age of children undergoing anterior cricoid resection was 3 years. There was no mortality. Tracheostomy decannulation was accomplished within 12 weeks following operation in all patients. It was necessary to remove a tracheal granuloma in one patient. Anterior cricoid wedge resection leaving the posterior portion of the cricoid in place is done to avoid recurrent nerve injury. It is a relatively simple and effective procedure. There has been minimal morbidity and no mortality. Follow-up from 1 to 11 years shows no recurrence of stenosis. There has been normal laryngeal and airway growth.

Child, Preschool↗
PubMed1990

Rectal prolapse: 17-year experience with the posterior repair and suspension.

Using a posterior repair and rectal suspension procedure for those patients who need surgical treatment of rectal prolapse, we have treated 46 patients over a period of 17 years at Children's Mercy Hospital in Kansas City, MO. One patient with caudal dysgenesis died of multiple congenital anomalies following two unsuccessful attempts at posterior repair and suspension. Four patients developed a recurrence afterwards, which was found to be due to sigmoid intussusception and, presumably, had played a major part in their original prolapse. Two of these required resection, one from the transanal approach and one from the transabdominal approach. One resolved spontaneously and another is as yet unresolved. Three patients had minor mucosal prolapse that was transient and two patients had extrusion of silk sutures but continued to have a very satisfactory result. Overall, 42 patients had satisfactory resolution of their rectal prolapse. Three of the four patients who had unsatisfactory results had associated anomalies that contributed to their poor outcome.

Child↗
PubMed1990

Blast trauma in a child.

In 1986, we cared for a four-year-old boy who was injured in the explosion of an illegal firecracker equivalent to one-third of a stick of dynamite. Although little has been reported on the injuries children sustain in an explosion, we found that this child's injuries were similar to those encountered in adults. This case is presented as illustrative of blast trauma in childhood, and as a review of blast injury.

Blast Injuries↗
PubMed1990

The long-term outcome following "special clearance" after vasectomy.

Between 1980 and 1985, 6067 out-patient vasectomies were performed under local anaesthesia at the Elliot Smith Clinic in Oxford. During this period 151 men (2.5%) were given a "special clearance". This sanctioned the discontinuation of other forms of contraception despite the persistence of scanty (less than 10,000/ml) sperm in 2 consecutively examined semen samples at least 7 months after vasectomy. These men have been reviewed and further specimens of semen requested after a minimum follow-up of 3 years (range 3-8); 50 patients supplied a specimen and all except 1 were azoospermic. No pregnancies attributable to failure of the vasectomy have been identified.

Adult↗
PubMed1989

The influence of MHC-compatible and MHC-incompatible antigen-presenting cells on the survival of MHC-compatible cultured murine keratinocyte allografts.

Our group has shown previously that APC-depleted cultured epidermal keratinocytes show prolonged survival when grafted onto normal MHC-incompatible adult mice. We show here that in vitro culture also improves significantly the survival of MHC-compatible keratinocyte allografts, although these nonrejected grafts are repopulated by host cells identified by their dendritic morphology and phenotype (class II+, leukocyte-common antigen+) as APCs. Reconstitution of cultured grafts, immediately prior to transplantation, with MHC-compatible dendritic cells of either donor or recipient origin, results in graft rejection--thus demonstrating that cultured cells can be rejected by the recipient animal--and suggests that a paucity of APCs in the immediate postgrafting period is responsible for the privilege afforded these grafts.

Animals↗
PubMed1988

Hepatic hemangioma: resection using hypothermic circulatory arrest in the newborn.

Hepatic hemangioma (hemangioendothelioma) is a benign vascular tumor with significant morbidity and mortality. Two newborn infants underwent partial hepatectomy for treatment of massive hepatic hemangioma, one with atrial septal defect and secondary congestive heart failure, and the other with symptomatic marked hepatomegaly. Cardiopulmonary bypass with induced deep hypothermic circulatory arrest was used in both patients in order to facilitate resection and prevent sudden massive blood loss. One infant also had closure of an atrial septal defect in addition to the partial hepatectomy. Both infants survived without complication and showed complete resolution of preoperative symptoms. This technique coupled with the use of fibrin glue is of value in infants with large hepatic hemangiomata and cardiac decompensation in the neonatal period.

Cardiopulmonary Bypass↗
PubMed1988

Histology of the intestine in human gastroschisis--relationship to intestinal malfunction: dissolution of the "peel" and its ultrastructural characteristics.

There are conflicting views on the pathogenesis of the intestinal malfunction seen in infants with gastroschisis. It has been variously ascribed to abnormalities of ganglion cells and smooth muscle elements, intestinal ischemia, and the "peel" which invests the serosa of the intestine. Review of the clinical and experimental literature showed only limited information on the histology of the eviscerated human intestine. In order to add to this data base, and to further investigate the pathogenesis of the intestinal malfunction from a histologic standpoint, we reviewed surgical and autopsy material from our experience with 105 neonates with gastroschisis. Ten specimens were satisfactory for evaluation from a standpoint of tissue integrity. The specific mural components of mucosa, submucosa, muscularis, and ganglion cells were examined and found to be either normal, or to show nonspecific abnormalities that varied from case to case, and were related mostly to intestinal infarction due to compromise of the gut at the site of the gastroschisis defect. In six patients, this progressed to atresia formation. The most consistent abnormalities were found in the serosal layer with its peel. Using special stains, the peel was found to be composed largely of fibrin and collagen. Based on this study, we feel that edema and ischemic changes, though often present, are much less prominent than the peel, as the leading histologic abnormality of the intestine of gastroschisis. Squamous epithelial cells were seen in the peel in four cases, suggesting that the peel had been "appliqued" onto the serosa of the herniated fetal gut.

Abdominal Muscles↗
PubMed1988

Properties of Thermus ruber Strains Isolated from Icelandic Hot Springs and DNA:DNA Homology of Thermus ruber and Thermus aquaticus.

Seventeen pink-pigmented strains of the genus Thermus were isolated from samples collected from thermal areas of Iceland. The strains were examined by using phenotypic characterization and DNA:DNA homology and were compared with recognized strains. Visually, the strains could be divided into three groups based on their pigmentation; however, spectroscopic studies of the pigments indicated little difference among them. Most strains required a vitamin supplement for growth and used fructose, maltose, mannose, or sucrose as the sole carbon source. In the presence of nitrate, two strains were able to grow under anaerobic conditions. The optimum growth temperature was 60 degrees C; growth did not occur at 30 or 70 degrees C.

Journal Article↗