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Biomedical subjects

J A Porter

Publications and source records attributed to J A Porter.

14 recordsLinked to original sources
PubMed1992

Arterial thromboembolic complications of inflammatory bowel disease. Report of three cases.

Extraintestinal manifestations of inflammatory bowel disease are legion and are demonstrated in one-third of those afflicted. In general, they do not mandate surgery. Three patients with active pancolonic ulcerative colitis developed arterial thromboembolic complications prior to surgical treatment. Thromboembolic complications are not fully understood, as is evidenced by the paucity of information in the literature, and only sporadic cases of arterial thromboemboli are found. These have been described primarily in the postsurgical patient. To ascertain whether others have encountered similar cases, a survey form was distributed to members of The American Society of Colon and Rectal Surgeons, yielding an additional 54 patients with thromboembolic complications. Approximately two-thirds were deep venous thromboses and/or pulmonary emboli. Ten patients had cerebrovascular accidents, and eight had arterial emboli. Eleven patients, over 21 percent, suffered multiple events. There were four resultant mortalities. An arterial thromboembolic event in a patient with ulcerative colitis is usually associated with pancolonic disease, has a poor long-term prognosis, and is an indication for colectomy.

Adult↗
PubMed1992

Differential localizations of and requirements for the two Drosophila ninaC kinase/myosins in photoreceptor cells.

The ninaC gene encodes two retinal specific proteins (p132 and p174) consisting of a protein kinase domain joined to a domain homologous to the head region of the myosin heavy chain. The putative myosin domain of p174 is linked at the COOH-terminus to a tail which has some similarities to myosin-I tails. In the current report, we demonstrate that the ninaC mutation results in light- and age-dependent retinal degeneration. We also show that ninaC flies display an electrophysiological phenotype before any discernible retinal degeneration indicating that the electrophysiological defect is the primary effect of the mutation. This suggests that ninaC has a role in phototransduction and that the retinal degeneration is a secondary effect resulting from the defect in phototransduction. To examine the requirements for the individual ninaC isoforms, mutant alleles were generated which express only p132 or p174. Elimination of p174 resulted in a ninaC phenotype as strong as the null allele; however, elimination of p132 had little if any effect. As a first step in investigating the basis for the difference in requirements for p174 and p132 we performed immuno-localization at the electron microscopic level and found that the two isoforms display different subcellular distributions in the photoreceptor cells. The p132 protein is restricted primarily to the cytoplasm and p174 to the rhabdomeres, the microvillar structure which is the site of action of many of the steps in phototransduction. This suggests that the p174 myosin-I type tail is the domain responsible for association with the rhabdomeres and that the substrate for the p174 putative kinase may be a rhabdomeric protein important in photo-transduction.

Aging↗
PubMed1992

A novel 7-nucleotide motif located in 3' untranslated sequences of the immediate-early gene set mediates platelet-derived growth factor induction of the JE gene.

A cohort of the serum and growth factor regulated immediate-early gene set is induced with slower kinetics than c-fos. Two of the first immediate-early genes characterized as such, c-myc and JE, are contained within this subset. cis-acting genomic elements mediating induction of the slower responding subset of immediate-early genes have never been characterized. Herein we characterize two widely separated genomic elements which are together essential for induction of the murine JE gene by platelet-derived growth factor, serum, interleukin-1, and double-stranded RNA. One of these elements is novel in several regards. It is a 7-mer, TTTTGTA, found in the proximal 3' sequences downstream of the JE stop codon. The 3' element is position dependent and orientation independent. It does not function in polyadenylation, splicing, or destabilization of the JE transcript. Copies of the 7-mer or its inverse are found at comparable 3' sites in 25 immediate-early genes that encode transcription factors or cytokines. Given its general occurrence, the 7-mer may be a required cis-acting control element mediating induction of the immediate-early gene set.

3T3 Cells↗
PubMed1991

The evolution of surgical endoscopic training. Meeting the American Board of Surgery requirements.

The American Board of Surgery requires that applicants become familiar with gastrointestinal endoscopy. This report retrospectively reviews Akron City Hospital's ten-year experience in surgical endoscopic training. In July, 1982, a two-month endoscopy rotation was established for fourth-year surgical residents. The average number of endoscopies performed by the resident as surgeon increased from 49.0 in 1984-85, to 167.7 in 1988-89. The percentage of endoscopies performed as surgeon increased from 46.4 per cent to 87.3 per cent during the same period. These increases are coincident with the addition of two trained surgical endoscopists to the faculty. This improvement in resident experience is attributed to an increase in endoscopies performed by faculty surgeons (634 procedures in 1988-89 vs. 291 procedures in 1984-85), and to an increase in percentage of procedures performed as surgeon with faculty gastroenterologists. Two of the three residents graduating in the final year of the study met the SAGES guidelines for upper GI endoscopy and colonoscopy. Based upon this ten-year experience, we recommend that surgical residencies desiring to develop endoscopic training recruit trained surgical endoscopists and develop a collaborative relationship between medical and surgical faculty.

Endoscopy, Digestive System↗
PubMed1990

Retroperitoneal air after routine hemorrhoidectomy. Report of a case.

Retroperitoneal air as a complication after routine hemorrhoidectomy has not been reported in the literature. This occurred recently after hemorrhoidectomy in a 34-year-old patient receiving glucocorticoid therapy for rheumatoid arthritis. Adverse steroidal effects of wound healing have been well documented. It is believed that steroid-induced tissue changes contributed to the development of this unique complication.

Adult↗
PubMed1990

Repeat percutaneous endoscopic gastrostomy (PEG): an outpatient procedure.

Patients who have previously undergone percutaneous endoscopic gastrostomy (PEG) with subsequent PEG removal occasionally require elective repeat PEG. Adhesion of the stomach to the abdominal wall after the original PEG allows repeat PEG to be performed as an outpatient procedure and full-volume tube feeding to be started immediately. Elective repeat PEG was performed in ten patients. Repeat PEG was performed at the site of the original PEG in all cases. Six of the ten repeat PEGs were performed as an outpatient procedure. No complications were attributed to repeat PEG, and full-volume tube feedings were tolerated in all cases when attempted. To obviate the need for repeat PEG, we recommend immediate replacement after inadvertent PEG removal and avoiding elective removal of PEGs used in patients with long-term neurologic impairment for at least 6 months.

Ambulatory Surgical Procedures↗
PubMed1990

Scleroderma is associated with differences in individual routes of drug metabolism: a study with dapsone, debrisoquin, and mephenytoin.

Exposure to certain environmental agents may induce a scleroderma-like syndrome in a small proportion of individuals. Differences in susceptibility could involve metabolic activation of a protoxin, with affected patients having a greater converting ability. This possibility was investigated in 84 patients with scleroderma and 108 control subjects with in vivo probes of specific pathways of metabolism. Scleroderma was associated with reduced hydroxylating activity for dapsone and S-mephenytoin, whereas the ability to hydroxylate debrisoquin and N-acetyl dapsone was similar in both groups. Logistic regression confirmed these associations based on the shift in frequency distribution. Individuals who were poor metabolizers for mephenytoin and only modest N-hydroxylators of dapsone had a tenfold increased risk of scleroderma (p = 0.008). Thus this combined metabolic impairment may be causally involved in the development of scleroderma or, alternatively, the disease may produce inhibition of selected metabolizing enzymes in a subset of patients.

Acetylation↗
PubMed1990

The contribution of N-hydroxylation and acetylation to dapsone pharmacokinetics in normal subjects.

The relative importance of N-hydroxylation and acetylation of dapsone to the oral clearance of dapsone (100 mg) was investigated in seven healthy volunteers. Plasma dapsone and monoacetyldapsone concentrations rose rapidly with subsequent similar monoexponential elimination. The oral clearance of dapsone was low (33 +/- 14 ml/min), with a threefold variability. Four subjects were identified as fast acetylators; however, differences in acetylation did not explain the variability in oral clearance. The cumulative urinary recoveries of dapsone and its hydroxylamine were approximately 20% of the dose. The formation clearance of hydroxylamine, which exhibited a tenfold intersubject variability, was closely associated with the oral clearance of dapsone (r = 0.96). Thus, the formation of the hydroxylamine is more important than acetylation in determining dapsone's intersubject variability in oral clearance. Variation in N-hydroxylation may have clinical consequences, because the hydroxylamine is considered to be important in dapsone-mediated toxicity.

Acetylation↗
PubMed1990

The beta-interferon-mediated antimitogenic state resembles the anti-viral state.

Much controversy regarding the effect of interferons in control of the animal cell cycle can be reconciled by acknowledging that, until recently, few laboratories enjoyed access to both pure interferons and pure growth-factor preparations. Using such reagents, we show data that suggest that antimitogenic state in Balb/c-3T3 cells by beta-interferon resembles the antiviral state in two important regards: dosage and kinetics. Picomolar concentrations of homogeneous beta-interferon inhibit the mitogenic response to recombinant platelet-derived growth-factor B chain homodimer. The antimitogenic response is seen only when cells are exposed to pure beta-interferon for an extended time prior to platelet-derived growth-factor treatment. The interferon-mediated antimitogenic state is exerted at some point in the cell cycle subsequent to c-myc gene induction.

Animals↗
PubMed1990

Management of premature removal of the percutaneous gastrostomy.

Percutaneous endoscopic gastrostomy (PEG) has become the preferred method of enteral access for nutritional support. With increased use of this modality, complications are encountered more frequently. Premature withdrawal, inadvertent removal of the gastrostomy tube within the first seven days after insertion, before adherence of the gastric serosa to the parietal peritoneum, has been an indication for laparotomy. This report describes the treatment of premature withdrawal by immediate endoscopic replacement. Over an 18-month period, 271 patients underwent insertion of a PEG. Five patients (1.8%) who inadvertently removed their gastrostomy tube within seven days of insertion were treated with immediate replacement using the retrograde string technique, avoiding laparotomy. All five PEGs were successfully replaced through the same gastrostomy site. Despite the presence of pneumoperitoneum, no patient developed peritonitis or other septic complications. Premature gastrostomy tube withdrawal is safely managed by endoscopic replacement and observation. Laparotomy is unnecessary and potentially meddlesome.

Aged↗
PubMed1979

Nurse education.

Explore the source record for details and available documents.

Australia↗
PubMedDate not supplied

Pneumoperitoneum following percutaneous endoscopic gastrostomy. Does the timing of panendoscopy matter?

Percutaneous endoscopic gastrostomy (PEG) has had a significant impact on enteral alimentation in patients unable to maintain adequate oral caloric intake. PEG avoids the morbidity and mortality associated with the traditional feeding gastrostomies placed by celiotomy. Several authors have documented benign, self-limiting pneumoperitoneum following PEG placement. No study has addressed whether the timing of panendoscopy in relation to gastric puncture has an effect on the incidence of post-PEG pneumoperitoneum. The authors prospectively studied 30 patients undergoing PEG. Panendoscopy was either performed before or after gastric puncture, and each patient then had abdominal radiographs to determine the presence of pneumoperitoneum. Four of 16 patients (25%) having panendoscopy prior to gastric puncture had radiographic evidence of pneumoperitoneum compared to three of 14 patients (23%) having panendoscopy following gastric puncture. The authors conclude that the timing of panendoscopy in relation to gastric puncture does not significantly effect the incidence of post-PEG pneumoperitoneum.

Aged↗