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Biomedical subjects

J R Johnston

Publications and source records attributed to J R Johnston.

At least 19 recordsLinked to original sources
PubMed1992

Hemoperitoneum complicating chronic peritoneal dialysis: single-center experience and literature review.

Hemoperitoneum is a well-recognized, if uncommon, complication of chronic peritoneal dialysis. In this review of 424 patients maintained on peritoneal dialysis at a single center during an 11-year period, 26 patients (6.1%) developed one or more episodes of hemoperitoneum. Three patients had hemoperitoneum on two separate occasions with different etiologies. One additional patient was seen on a hospital consultative service. Three types of bleeding episodes were observed. Twenty-one of 30 (70%) were benign, consisting of pink-tinged dialysate with little clinical consequence (group 1). Three (10%) consisted of minor hemoperitoneum associated with significant intra-abdominal pathology (group 2), and six (20%) required active intervention (group 3). The most frequent cause of hemoperitoneum was bleeding related to menstruation or ovulation; hemoperitoneum was more common in women than in men. Two patients had hemoperitoneum occurring after more than 6 years on dialysis. In both, the etiology was sclerosing peritonitis, an association not previously noted. The less common etiologies of hemoperitoneum encountered in our patients were similar to those in reports from other centers and are compiled here.

Female↗
PubMed1992

Spoken and written language relationships in language/learning-impaired and normally achieving school-age children.

Students with language/learning impairment (LLI) and three groups of normally achieving children matched for chronological age, spoken language, and reading abilities wrote and told stories that were analyzed according to a three-dimensional language analysis system. Spoken narratives were linguistically superior to written narratives in many respects. The content of written narratives, however, was organized differently than the content of spoken narratives. Spoken narratives contained more local interconnections than global interconnections; the opposite was true for written narratives. LLI and reading-matched children evidenced speaking-writing relationships that differed from those of the age- and language-matched children in the way language form was organized. Further, LLI children produced more grammatically unacceptable complex T-units in their spoken and written stories than students from any of the three matched groups. The discussion focuses on mechanisms underlying the development of speaking-writing differences and ramifications of spoken-language impairment for spoken and written-language relationships.

Child↗
PubMed1992

Calcium mass transfer in peritoneal dialysis patients using 2.5 mEq/l calcium dialysate.

Standard peritoneal dialysate has a relatively high calcium concentration of 3.5 mEq/l. Peritoneal dialysis patients thus gain calcium from the dialysate which contributes to the risk of hypercalcemia. Dialysate with 2.5 mEq/l calcium is now available. Theoretically, using dialysate with this calcium content, calcium transfer should be negative (from the patient into the dialysate) when the patient is hypercalcemic, and positive when the patient is normocalcemic or hypercalcemic. Thus, 2.5 mEq/l calcium dialysate may allow larger doses of calcium carbonate to be prescribed. We compared calcium mass transfer (CMT) in 17 stable peritoneal dialysis patients using 3.5 and 2.5 mEq/l calcium dialysate. A solution of 2.05 l, 1.5 g/dl dextrose was dwelled for 4 hours. Calcium was measured in the drained dialysate and serum (total and ionized). Mean CMT was 0.7 +/- 0.5 mEq/exchange using 3.5 mEq/l calcium dialysate and -0.9 +/- 0.9 mEq/exchange using 2.5 mEq/l calcium dialysate (p less than 0.0001). At the time of the CMT studies, the mean serum ionized calcium levels were identical for the two groups (2.6 mEq/l). CMT correlated inversely with serum total calcium, serum ionized calcium, and drained dialysate volume. During hypercalcemia calcium transfer was from the dialysate to the patient when 3.5 mEq/l calcium dialysate was used, but from the patient to the dialysate when 2.5 mEq/l calcium dialysate was used. We conclude that 2.5 mEq/l calcium dialysate is effective in removing calcium and will be helpful in preventing hypercalcemia when large doses of oral calcium compounds are prescribed as a phosphate binder.

Adult↗
PubMed1991

Cloning, sequencing and expression of the Schwanniomyces occidentalis NADP-dependent glutamate dehydrogenase gene.

The cloned NADP-specific glutamate dehydrogenase (GDH) genes of Aspergillus nidulans (gdhA) and Neurospora crassa (am) have been shown to hybridize under reduced stringency conditions to genomic sequences of the yeast Schwanniomyces occidentalis. Using 5' and 3' gene-specific probes, a unique 5.1 kb BclI restriction fragment that encompasses the entire Schwanniomyces sequence has been identified. A recombinant clone bearing the unique BclI fragment has been isolated from a pool of enriched clones in the yeast/E. coli shuttle vector pWH5 by colony hybridization. The identity of the plasmid clone was confirmed by functional complementation of the Saccharomyces cerevisiae gdh-1 mutation. The nucleotide sequence of the Schw. occidentalis GDH gene, which consists of 1380 nucleotides in a continuous reading frame of 459 amino acids, has been determined. The predicted amino acid sequence shows considerable homology with GDH proteins from other fungi and significant homology with all other available GDH sequences.

Amino Acid Sequence↗
PubMed1991

Iatrogenic hypercalcemia in hemodialysis patients.

Calcium carbonate is frequently used in large doses as a phosphorus binder in hemodialysis patients, which often results in hypercalcemia. In most studies in which calcium carbonate is prescribed to control serum phosphorus levels the patients are not given calcitriol. However, calcitriol may be necessary for suppression of parathyroid hormone. The risk of hypercalcemia when calcium supplements are used in conjunction with calcitriol has not previously been examined in detail. We reviewed the charts of 74 hemodialysis patients (119 patient dialysis years) to determine the relationship of serum calcium to calcitriol, calcium therapy, and PTH levels. Twenty-eight patients (38%) were hypercalcemic at some point. Calcitriol therapy significantly increased the risk of hypercalcemia, independently of calcium therapy (p = 0.032). However, patients on a low dose of calcitriol were more than twice as likely to be hypercalcemic than patients on higher doses. Mean PTH levels were lower in the patients on the lower doses of calcitriol, indicating less severe hyperparathyroid disease. We conclude that hypercalcemia is a common complication in hemodialysis patients on calcitriol and calcium carbonate. Whether lowering the dialysate calcium, as suggested by other investigators, will successfully decrease the risk of hypercalcemia without worsening hyperparathyroidism remains to be determined.

Adult↗
PubMed1991

An analysis of ten-year trends in infections in adults on continuous ambulatory peritoneal dialysis (CAPD).

Infectious complications are the Achilles heel of CAPD. To determine trends in these events, we analyzed the CAPD related infections of 303 adults on CAPD at a single university center between 1979 and 1989. During this decade the percentage of insulin-dependent diabetics increased from 14% to 39% (p less than 0.005). Peritonitis rates fell from 2.4 episodes/y in 1979 to 0.8 episodes/y in 1989. The proportion of patients with multiple episodes of peritonitis decreased (40% of the patients in 1979-1982 vs 15% in 1983-1989, p = 0.0001) while the proportion of patients with no episodes of peritonitis increased during the same periods (29% vs 49%, p = 0.005). The proportion of peritonitis episodes due to S. aureus rose over the 10-year period (p = 0.005), while those due to S. epidermidis decreased (p less than 0.10). The overall incidence of S. aureus peritonitis remained unchanged. Catheter infection rates initially increased and then fell during the decade; S. aureus remained the predominant cause. The proportion of peritonitis episodes associated with catheter infection rose (13% in 1982 vs 24% in 1989, p = 0.025), and in 1989, 80% of these episodes were caused by S. aureus. Catheter loss was also primarily due to S. aureus infections in 1989 (80%). Infections due to P. aeruginosa were a persistent problem. The proportion of patients transferring to hemodialysis each year paralleled catheter loss rates, which in turn appeared to be more related to catheter infection rates than to peritonitis rates. We conclude that control of S. aureus and P. aeruginosa will be the key to future reductions in the infectious complications of CAPD patients.

Catheters, Indwelling↗
PubMed1991

Pulmonary and renal toxicity of intravenous immunoglobulin.

Three patients treated with intravenous immunoglobulin developed respiratory difficulty and decreased renal function. Previously reported adverse reactions to this class of drugs have included pulmonary toxicity but not, to the best of our knowledge, renal toxicity. Renal dysfunction was mild in one patient but severe in two patients, one of whom required temporary hemodialysis. In all three patients, renal function returned to the pretreatment level after stopping the drug. Urinalysis and urine sodium concentration at the onset of renal failure were consistent with pre renal azotemia although renal biopsy performed later in one patient showed acute tubular necrosis. The exact mechanism of toxicity is unknown, but the fact that all three cases occurred with a particular immunoglobulin preparation would suggest that a contaminant, possibly aggregated IgG might be responsible.

Acute Kidney Injury↗
PubMed1991

The effect of body weight on CAPD related infections and catheter loss.

CAPD related infections and catheter loss continue to be the major problems facing the peritoneal dialysis patient. Few risk factors for infections and catheter loss have been identified. We hypothesized that overweight and underweight patients may be at increased risk for infections and catheter related problems. We examined the effect of the patient's weight at the start of peritoneal dialysis on the subsequent peritonitis and catheter infection rates, as well as catheter loss. Weight was expressed as a percentage of ideal body weight (IBW). Those patients who were more than 110% of IBW were considered to be overweight, 90 to 110% of IBW normal and less than 90%, underweight. An equivalent percentage of patients were overweight and underweight at the initiation of peritoneal dialysis (55/228, 24% for both groups). Overweight, normal, and underweight patients had peritonitis rates of 1.0, 0.9, and 0.8 episodes/y and catheter infection rates of 1.1, 1.2, and 0.8 episodes/y, respectively. Despite these similar rates, catheter loss due to infectious complications was greatest in the overweight group and least in the underweight group (p less than 0.05). No obvious explanation for the difference in catheter loss rate was found. Neither S. aureus nor P. aeruginosa infections occurred more frequently in the overweight patients. However, S. aureus infections more often led to catheter loss in the overweight patients. Catheter loss due to catheter leaks and failure to drain was similar in the three groups of patients. We conclude that deviation from ideal body weight at the initiation of dialysis is not a risk factor for CAPD related infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Organ donation.

Explore the source record for details and available documents.

Humans↗
PubMed1990

Two staining methods for selectively detecting isomaltase and maltase activity in electrophoresis gels.

Two methods for specifically detecting maltase, alpha-glucosidase, or isomaltase activity in electrophoresis gels are described. Both systems couple the formation of glucose by enzyme action on maltose or isomaltose to the generation of a colored product. System A uses an agarose overlay which contains substrate, glucose oxidase, peroxidase, 2,4-dichlorophenol, and 4-L-amino-phenazone. A purple color is produced at the site of enzyme activity. No hazardous chemicals are used at any stage. The stain is simple, rapid, sensitive, and inexpensive and does not interfere with subsequent protein staining. However, the stain is not permanent. System B was developed to give a permanent stain. The gel is overlaid with agarose containing substrate, glucose oxidase, phenazine methosulfate, and nitroblue tetrazolium. Glucose production results in the nitroblue tetrazolium being oxidized to an insoluble formazan with a dark blue color. This stain is also sensitive, rapid, and inexpensive but does use hazardous chemicals and if overstaining occurs this can interfere with subsequent protein staining. Neither system inactivates the localized enzymes which can be recovered from the gel if desired.

Aminopyrine↗
PubMed1990

Propofol anesthesia for major thoracic surgery.

One hundred patients undergoing elective thoracic surgery were anesthetized with propofol as a continuous intravenous infusion. In 60 patients, nitrous oxide was used for supplementation. The technique proved satisfactory, but induction of anesthesia was associated with significant decreases in blood pressure. The use of nitrous oxide markedly reduced the propofol requirements, and prolonged the time to the first spontaneous breath during recovery. The mean infusion rate of propofol was 7.2 +/- 2.72 mg/kg/h with air-oxygen, and 5.7 +/- 1.97 mg/kg/min with nitrous oxide-oxygen (P less than 0.01). This technique seems to be a satisfactory alternative for patients primarily requiring an intravenous anesthetic during thoracic surgery.

Anesthesia Recovery Period↗
PubMed1990

Methicillin-resistant staphylococcal infections in an outpatient peritoneal dialysis program.

In view of the increasing concern about hospital-acquired methicillin resistance, we examined the sensitivities and outcome of staphylococcal infections related to outpatient peritoneal dialysis over a 5-year period. Data on all episodes of peritonitis (n = 360) and catheter infections (n = 507) were gathered prospectively from January 1984 to December 1988. The numbers of patients on peritoneal dialysis each year ranged from 136 in 1984 to 109 in 1987. Fifteen methicillin-resistant staphylococcal infections (MRSI) related to outpatient peritoneal dialysis occurred. Three were due to methicillin-resistant Staphylococcus aureus found in infected exit sites (2.3% of all S aureus catheter infections). Two of these infections occurred in a continuous ambulatory peritoneal dialysis (CAPD) patient who carried methicillin-resistant S aureus in his nares. The other 12 methicillin-resistant organisms were coagulase-negative staphylococci that caused peritonitis. There was a significant increase in the percentage of episodes of coagulase-negative staphylococci peritonitis caused by methicillin-resistant organisms; from 5% (3/57) in 1984 through 1986 to 28% (9/32) in 1987 through 1988 (P less than 0.005). In view of the high percentage of coagulase-negative staphylococci peritonitis that is methicillin-resistant, vancomycin rather than cephalosporins should be used for initial treatment.

Humans↗
PubMed1990

Children of divorce: recent findings regarding long-term effects and recent studies of joint and sole custody.

The 10-year study revealed that the effects of divorce on children are often long lasting. Children are especially affected because divorce occurs within their formative years. What they see and experience during the failing marriage becomes a part of their view of themselves and of society. Although the findings from the study are, in some respects, dismaying, what emerges clearly is that a successfully reestablished family or a successful remarriage can improve the quality of life for both adults and children. The divorce may resolve the family conflict and allow the children to preserve a relationship with both parents. Divorce may also be useful in putting some distance between a child and a disturbed parent. Under these conditions, children may show accelerated maturity and independence. They may also bring to young adulthood a morality that places high value on sustaining relationships and on love, fidelity, and compassion. The results of the longitudinal study, as well as those of the two joint custody studies, indicate that ongoing conflict between divorced parents has especially detrimental effects on the children and that children are particularly at risk when they have frequent and continuing access to both parents who are hostile and uncooperative with each other. Mandated joint custody and frequent visitation in these situations may not be advisable. On the other hand, among children in chronically disturbed and disputing families, there is a wide range of individual coping responses and degrees of resilience. In the final analysis, individual temperaments should be considered and a careful evaluation made of how each child is coping in his or her own particular family environment.

Adaptation, Psychological↗
PubMed1990

The use of subcutaneous erythropoietin in CAPD patients.

There is little data available on the use of erythropoietin in CAPD patients. The available pharmacokinetic and clinical data suggest that a low dose of subcutaneous erythropoietin might be effective. Seven CAPD patients, without active malignancy or infection, self-administered erythropoietin, 2,000 units (a mean of 32 units/kg) subcutaneously, three times a week. The Hct rose from 23% to 31% in a mean treatment time of 7 weeks, or a rate of rise of 1.2% per week. Three of the patients had previously been transfusion dependent. One of these patients and two additional had iron overload (ferritin level greater than 2,000 ng/ml). The drug was paid for by Medicaid (two patients) or private insurance, with the patient paying the uncovered portion, generally 20%. Side effects were minimal. Low dose subcutaneous erythropoietin is effective in CAPD patients.

Adult↗
PubMed1989

Atheroembolic involvement of renal allografts.

Renal atheroembolism is a well-recognized cause of renal insufficiency. Two renal allograft recipients with cholesterol atheroemboli in their allograft biopsies are described. In one patient, the origin of the atheroemboli was the recipient aorta while in the second patient the source was the donor. Renal allograft atheroembolism should be considered in elderly recipients or recipients of kidneys from older donors.

Adult↗
PubMed1989

Dimensional thinking in language impaired children.

This study investigated the dimensional knowledge evidenced by language impaired (LI) preschoolers. Ten LI and 10 language normal (LN) children, aged 3:6 to 5:9, were asked to solve verbal and nonverbal problems requiring color and size judgments. There were no group differences on the verbal task, but the LI children performed less well than the LN children on the nonverbal task. Much of this difference stemmed from their difficulty with size items. The ordinal nature of the size dimension implies greater cognitive processing demands than are inherent in nominal dimensions such as color. Given the known processing limitations of language impaired children, this complexity apparently can lead to erroneous judgment even when requisite knowledge is present. It may also contribute to delays in the initial construction of dimensional knowledge.

Child, Preschool↗
PubMed1989

Vecuronium infusions for prolonged muscle relaxation in the intensive care unit.

Neuromuscular blockade by vecuronium infusion is described in 13 patients requiring ventilation in an ICU for periods of 15 to 68 h. A loading dose of vecuronium (0.1 mg/kg) was given, followed by continuous infusion adjusted to maintain approximately 90% block as assessed by the presence of one response to a Train-of-Four stimulation. The average infusion rate was 0.103 mg/kg.h. The average time to complete recovery of myoneural function, as assessed by an obviously sustained response to tetanic stimulation, after the termination of the vecuronium infusion was 28 min. There were no adverse cardiovascular or toxic effects noted as a result of vecuronium administration. Vecuronium administered by infusion produced satisfactory neuromuscular relaxation in patients requiring ventilation in the ICU.

Adult↗