Regulation by homeoproteins: a comparison of deformed-responsive elements.

Homeotic genes of Drosophila melanogaster encode transcription factors that specify segment identity by activating the appropriate set of target genes required to produce segment-specific characteristics. Advances in understanding target gene selection have been hampered by the lack of genes known to be directly regulated by the HOM-C proteins. Here we present evidence that the gene 1.28 is likely to be a direct target of Deformed in the maxillary segment. We identified a 664-bp Deformed Response Element (1.28 DRE) that directs maxillary-specific expression of a reporter gene in transgenic embryos. The 1.28 DRE contains in vitro binding sites for Deformed and DEAF-1. The Deformed binding sites do not have the consensus sequence for cooperative binding with the cofactor Extradenticle, and we do not detect cooperative binding to these sites, though we cannot rule out an independent role for Extradenticle. Removing the four Deformed binding sites renders the 1.28 DRE inactive in vivo, demonstrating that these sites are necessary for activation of this enhancer element, and supporting the proposition that 1.28 is activated by Deformed. We show that the DEAF-1 binding region is not required for enhancer function. Comparisons of the 1.28 DRE with other known Deformed-responsive enhancers indicate that there are multiple ways to construct Deformed Response Elements.

Peptidases and amino acid catabolism in lactic acid bacteria.

The conversion of peptides to free amino acids and their subsequent utilization is a central metabolic activity in prokaryotes. At least 16 peptidases from lactic acid bacteria (LAB) have been characterized biochemically and/or genetically. Among LAB, the peptidase systems of Lactobacillus helveticus and Lactococcus lactis have been examined in greatest detail. While there are homologous enzymes common to both systems, significant differences exist in the peptidase complement of these organisms. The characterization of single and multiple peptidase mutants indicate that these strains generally exhibit reduced specific growth rates in milk compared to the parental strains. LAB can also catabolize amino acids produced by peptide hydrolysis. While the catabolism of amino acids such as Arg, Thr, and His is well understood, few other amino acid catabolic pathways from lactic acid bacteria have been characterized in significant detail. Increasing research attention is being directed toward elucidating these pathways as well as characterizing their physiological and industrial significance.

Genetic characterization of a cell envelope-associated proteinase from Lactobacillus helveticus CNRZ32.

A cell envelope-associated proteinase gene (prtH) was identified in Lactobacillus helveticus CNRZ32. The prtH gene encodes a protein of 1,849 amino acids and with a predicted molecular mass of 204 kDa. The deduced amino acid sequence of the prtH product has significant identity (45%) to that of the lactococcal PrtP proteinases. Southern blot analysis indicates that prtH is not broadly distributed within L. helveticus. A prtH deletion mutant of CNRZ32 was constructed to evaluate the physiological role of PrtH. PrtH is not required for rapid growth or fast acid production in milk by CNRZ32. Cell surface proteinase activity and specificity were determined by hydrolysis of alpha(s1)-casein fragment 1-23 by whole cells. A comparison of CNRZ32 and its prtH deletion mutant indicates that CNRZ32 has at least two cell surface proteinases that differ in substrate specificity.

Successful management of myocardial infarction during pregnancy in a renal transplant recipient.

Myocardial infarction (MI) complicating pregnancy in a renal transplant recipient is described. Management challenges of MI in pregnancy and the possible predisposing roles of renal transplantation and erythropoietin (EPO) use are discussed.

Apophysomyces elegans infection in a renal transplant recipient.

A 50-year-old cadaveric renal transplant recipient on immunosuppressive therapy is described with post-traumatic cutaneous infection caused by Apophysomyces elegans. He showed no evidence of hematogenous dissemination and recovered fully after therapy with extensive local debridement and amphotericin B lipid complex. An apparent drug-drug interaction between amphotericin B lipid complex and cyclosporine was encountered. The course of A elegans infection in transplant recipients may be similar to that described in immunocompetent hosts. A elegans infection should be considered in evaluation of post-traumatic cutaneous infection not readily responsive to antibacterial therapy.

Clinical and medicoeconomic impact of the cyclosporine-diltiazem interaction in renal transplant recipients.

The effect of the diltiazem-cyclosporine interaction on cyclosporine pharmacokinetics, pharmacodynamics, and pharmacoeconomics was studied in 10 recipients of renal allografts. Each subject was studied while receiving diltiazem 60 mg twice/day and while not taking the drug. After achieving steady-state conditions, cyclosporine and metabolite concentrations were determined in whole blood from samples drawn after the morning cyclosporine dose. After pharmacokinetic analysis, all patients were followed for 6 months during treatment with cyclosporine plus diltiazem or cyclosporine alone. Cyclosporine blood clearance decreased significantly after treatment with diltiazem (18.0-11.0 ml/min.kg; p = 0.008). The apparent volume of cyclosporine distribution also decreased significantly (4.26-2.62 L/kg; p < 0.05). After 6 months, diltiazem had no effect on renal function indexes, and no apparent effect on immunosuppression. Alterations in cyclosporine clearance and apparent volume of distribution secondary to diltiazem result in dosage reduction and potential cost savings in transplant pharmacotherapy. The mean decrease in cyclosporine dosage requirements would produce a cost saving of $1520 or 28% per patient per year.

The effect of long-term intravenous calcitriol administration on parathyroid function in hemodialysis patients.

Secondary hyperparathyroidism is common in dialysis patients. Intravenous calcitriol has proven to be an effective therapy for the reduction of parathyroid hormone (PTH) levels. However, the effect of i.v. calcitriol on parathyroid function, defined as the sigmoidal PTH-calcium curve developed during hypocalcemia and hypercalcemia, has not been evaluated during the prolonged administration of i.v. calcitriol. Six hemodialysis patients with marked secondary hyperparathyroidism, PTH levels greater than 500 pg/mL (normal, 10 to 65 pg/mL), were treated for 42 wk with 2 micrograms of i.v. calcitriol after each hemodialysis. Parathyroid function was evaluated before and after 10 and 42 wk of calcitriol therapy. Between baseline and 42 wk, the basal PTH level decreased from 890 +/- 107 to 346 +/- 119 pg/mL (P less than 0.02) and the maximally stimulated PTH level decreased from 1293 +/- 188 to 600 +/- 140 pg/mL (P less than 0.01). In addition, calcitriol administration significantly decreased PTH levels throughout the hypocalcemic range of the PTH-calcium curve. Although the slope of the PTH-calcium curve (with maximal PTH as 100%) decreased between baseline and 42 wk (P less than 0.05), the set point of calcium did not change. Two patients with a decrease in both basal and maximally stimulated PTH levels after 10 wk of calcitriol, developed marked hyperphosphatemia between 10 and 42 wk; this resulted in an exacerbation of hyperparathyroidism despite continued calcitriol therapy. In conclusion, prolonged i.v. calcitriol administration is an effective treatment for secondary hyperparathyroidism in hemodialysis patients provided that reasonable control of the serum phosphate is achieved. In addition, the slope of the PTH-calcium curve may be a better indicator of parathyroid cell sensitivity than the set point of calcium.

Two-needle calculation of recirculation compared with the standard three-needle method.

A two-needle method for calculating recirculation was compared with the standard three-needle method, substituting the standard phlebotomy of a remote vessel during dialysis with blood obtained from the dialyzer inlet needle 15 minutes after the termination of dialysis. Twenty patients were studied prospectively. There was no significant difference between corrected blood flow calculated with the standard and two-needle methods. The BUN obtained from the inlet line needle 15 minutes after conclusion of the treatment did not differ significantly from the BUN concentration in the specimen from a contralateral arm drawn five minutes before termination of dialysis. Recirculation calculated by the two-needle method correlated well with the results obtained with the standard three-needle method. The two-needle method provides a convenient alternative to the standard three-needle method of determining recirculation.

Pharmacokinetics of single-dose oral ciprofloxacin in patients undergoing chronic ambulatory peritoneal dialysis.

The prevention and treatment of peritonitis in patients undergoing peritoneal dialysis is often complicated by several factors, including nephrotoxicity, requirement for hospitalization, parenteral antibiotic therapy, and infection caused by resistant microorganisms. Ciprofloxacin, a new carboxyquinolone derivative, may offer the advantages of oral administration, a broad spectrum of antibacterial activity, and safety for the management of these patients. The pharmacokinetics of ciprofloxacin in serum and peritoneal fluid of eight adult patients undergoing chronic ambulatory peritoneal dialysis (CAPD) were investigated. Each patient ingested a single 750-mg dose of ciprofloxacin, and drug concentrations were measured by high-pressure liquid chromatography in serum and peritoneal fluid for 48 h after the dose. Serum concentrations reached a mean peak of 3.6 micrograms/ml 1 to 2 h after the oral dose. The mean terminal serum half-life was 16.8 h, and the mean peritoneal fluid/serum concentration ratio was 0.64. The mean peak ciprofloxacin concentration in peritoneal fluid was 1.3 micrograms/ml, and the bioactivity of the drug in peritoneal fluid was confirmed. These data indicated that therapeutic concentrations of ciprofloxacin against bacterial pathogens commonly associated with peritonitis in CAPD patients may be achievable in the peritoneal fluid after oral administration to patients undergoing CAPD. In addition, the pharmacokinetic data provide guidelines for further clinical studies of oral ciprofloxacin in CAPD patients.

Effect of dialysis and ultrafiltration on osmolality, colloid osmotic pressure, and vascular refilling rate.

The effect of regular dialysis and isolated ultrafiltration on plasma osmolality, plasma colloid osmotic pressure (COP), plasma volume, and vascular refilling rate was evaluated in maintenance dialysis patients. Nineteen patients underwent regular dialysis and 11 isolated ultrafiltration. Blood samples from these subjects were obtained from arterial or venous dialysis system ports and peripheral veins. For any decrease in plasma volume, there was an increment in COP with each procedure in both venous and arterial ports and the presence of a progressive decrease of plasma osmolality was observed only during regular dialysis. Second, five additional patients underwent 2 hrs of regular dialysis and isolated ultrafiltration in separate sessions removing comparable amounts of fluid (approximately 2.5 liter); after 2 hrs, there were no differences in the changes of plasma volume and COP, but again plasma osmolality decreased only during regular dialysis. These studies demonstrate that moderate changes in plasma osmolality do not affect COP. Furthermore, the ability of the plasma to recruit fluid and generate vascular refilling (as assessed by COP) is similar during regular dialysis and isolated ultrafiltration, provided the rates of ultrafiltration are the same.

Chronic renal failure, dialysis, and neuropsychological function.

Hemodialysis patients, nondialyzed azotemic patients and control subjects with chronic physical disabilities were tested in psychometric measures of attention, memory, and visuomotor speed and coordination. There was relatively little difference between the performance of dialysis patients and controls and no significant correlations were found between years of dialysis treatment and performance on any task. In contrast, nondialyzed azotemic patients were impaired on 9 of 14 tasks relative to controls and/or dialysis patients. Measured levels of blood urea nitrogen (BUN) and serum creatinine were significantly correlated with the performance of nondialyzed azotemic patients on several tasks. These results demonstrate a relationship between degree of renal failure and cognitive and perceptual-motor functioning. The mild impairments evident in dialysis patients do not seem to be directly attributable to dialysis treatments. Rather, the onset of hemodialysis appears to have beneficial effects on neuropsychological function.

Surgical treatment of pericarditis in the dialysis patient.

Eighteen patients with pericarditis complicating chronic renal failure who were unresponsive to medical therapy underwent surgical decompression of the pericardium for either pericardial tamponade [16] or constrictive pericarditis [2]. There was one perioperative death and minimal morbidity. Preoperative pericardiocentesis in nine patients afforded only temporary relief in most of the patients and caused a life-threatening pericardial tamponade in one patient. Creation of a pericardial window through a left anterior thoracotomy was the procedure of choice in patients without signs of constrictive pericarditis or posterior loculated effusions and had excellent long-term results. We recommend early surgical treatment of uremic pericarditis in all patients with hemodynamic instability, enlarging pericardial effusion, or effusion that is unresponsive to intensive medical therapy.

Hypermagnesemia as a cause of refractory hypotension, respiratory depression, and coma.

Hypermagnesemia developed in a patient as a result of excess antacid ingestion, bowel obstruction, and renal failure. Before the diagnosis was considered, refractory hypotension, respiratory depression, and coma developed, all of which were eventually reversed through the lowering of the serum magnesium concentration by hemodialysis.

Relief of idiopathic generalized pruritus in dialysis patients treated with activated oral charcoal.

The effect of oral charcoal on idiopathic generalized pruritus in 11 stable patients undergoing maintenance hemodialysis was compared to that of placebo dextrose in a controlled, double-blind, cross-over study. Contrasted to placebo, charcoal, 6 g daily for 8 weeks, relieved pruritus subjectively in all but one patient (P = 0.01). Symptomatic relief from pruritus coincided with objective resolutions of active, scratch-induced skin lesions (P = 0.03). No significant alterations were noted in the serum concentrations of standard laboratory variables, including lipids, alkaline phosphatase, phosphorus, or calcium, during treatment with either charcoal or placebo. No adverse effects from the charcoal were noted during the study.