Recurring enteric peritonitis associated with non-perforating colon carcinoma.

Peritonitis of enteric origin may occur during treatment with peritoneal dialysis due to visceral perforation or injury or, in the absence of perforation, due to transmural migration of enteric bacteria across the bowel wall into the peritoneal cavity. To the best of our knowledge, peritonitis has not previously been reported associated with carcinomatous colon polyp in the absence of bowel wall perforation. We describe the case of a 31-year-old female who experienced recurring episodes of enteric peritonitis associated with a clinically occult adenocarcinoma of the colon, without having any other known risk factors for peritonitis. A 15 mm carcinomatous polyp was not visible on CT scan but was found at colonoscopy with polypectomy. She proceeded to transverse colectomy; the resected colon showed no evidence of bowel wall perforation. This case demonstrates that a non-perforating carcinomatous polyp of the colon may predispose to enteric peritonitis in the setting of peritoneal dialysis, and it emphasizes the importance of making an aggressive search for underlying pathology, in patients who present with recurring enteric peritonitis or unusual presentations of enteric peritonitis.

Barriers to the delivery of adequate hemodialysis in ESRD Network 4.

Dialysis dose has been established as a determinant of morbidity and mortality in chronic hemodialysis patients. To identify remediable barriers to the delivery of adequate hemodialysis, we examined factors that affected adherence to prescribed dialysis dose. End-Stage Renal Disease (ESRD) Network 4 facilities that fell into the lowest quintile in measures of dialysis adequacy were studied. At the time of this study, Network 4 was composed of 178 dialysis facilities in Delaware and Pennsylvania. Those 29 facilities had an average delivered urea reduction ratio (URR) of <0.67 and/or 71% of patients with a URR of 0.65. (The mean URR value of Network 4 was 0. 699 with a compliance ratio of 80%.) Dialysis treatment sheets were reviewed for all patients in the 29 facilities for all treatments during a calendar week. Predialysis and postdialysis blood urea nitrogen (BUN) values from 1 treatment during this week were used to calculate URR and Kt/V. A total of 1,339 patients with a mean age of 61.9 +/- 15.1 years and a mean duration of ESRD of 3.4 +/- 3.3 years were dialyzed in the 29 units. Mean prescribed duration of dialysis (T) was 219 +/- 26 min. with a mean blood flow rate (BFR) of 393 +/- 62 mL/min. Concordance between the prescribed and delivered T (-5 min), BFR (-50 mL/min), and hemodialyzer were assessed, by patient, for each treatment (Tx). Characteristics of a delivered Kt/V < 1.2 were duration <4 hours, BFR < 350 mL/min, patient weight > 100 kg, and delivered BFR 50 mL/min less than prescribed BFR. Multivariate analysis of the relationship between delivered dose of dialysis and patients and treatment characteristics identified black race, male gender, and younger age as demographic factors associated with low delivered dose. Potential remediable barriers identified by this analysis included reduced treatment time (>10%) and use of catheters for angioaccess. These data suggest components of the dialysis process that might be targeted in future quality improvement projects to improve the adequacy of dialysis delivery.

Improving compliance with the dialysis prescription as a strategy to increase the delivered dose of hemodialysis: an ESRD Network 4 quality improvement project.

Delivery of an inadequate dose of hemodialysis is associated with a significant increase in the relative risk of both hospitalization and death. We hypothesized that noncompliance with the dialysis prescription, defined as failure to achieve the prescribed blood flow, failure to dialyze for the prescribed duration, or failure to use the prescribed dialyzer, was a significant factor in patients not achieving a urea reduction ratio (URR) of > or =0.65. We identified the 29 dialysis facilities in ESRD Network 4 that had the lowest average URR and/or lowest percent of patients with a URR > or =0.65 based on quarterly data reports. Each facility was surveyed by review of all dialysis treatment sheets from a single week by network staff to evaluate for noncompliance with the dialysis prescription. Facility-specific data were reported back to each facility. Each facility was required to develop a facility-specific quality improvement plan after receiving intensive education on the quality improvement process. After 9 months the facilities were resurveyed. Although the compliance with the dialysis prescription decreased from 54.0% to 53.6% (P =.026), the delivered URR increased from 0.679 +/- 0.072 to 0.688 +/- 0.070 (P =.026) with an increase in the percentage of patients with a URR > or = 0.65 from 69.7% to 75% (P =.0096). Kt/V increased from 1.37 +/- 0.26 to 1.41 +/- 0.27 (P =. 0001). Analysis of the process changes instituted by the individual facilities showed an increase in the prescribed dose of dialysis. Thus, although the process goal of improved compliance with the dialysis prescription was not achieved, the outcome goal of an increased delivered dose of dialysis was met through an alternative process change of an augmented dialysis prescription.

A systematic, genome-wide, phenotype-driven mutagenesis programme for gene function studies in the mouse.

As the human genome project approaches completion, the challenge for mammalian geneticists is to develop approaches for the systematic determination of mammalian gene function. Mouse mutagenesis will be a key element of studies of gene function. Phenotype-driven approaches using the chemical mutagen ethylnitrosourea (ENU) represent a potentially efficient route for the generation of large numbers of mutant mice that can be screened for novel phenotypes. The advantage of this approach is that, in assessing gene function, no a priori assumptions are made about the genes involved in any pathway. Phenotype-driven mutagenesis is thus an effective method for the identification of novel genes and pathways. We have undertaken a genome-wide, phenotype-driven screen for dominant mutations in the mouse. We generated and screened over 26,000 mice, and recovered some 500 new mouse mutants. Our work, along with the programme reported in the accompanying paper, has led to a substantial increase in the mouse mutant resource and represents a first step towards systematic studies of gene function in mammalian genetics.

Comparison of the Difco EZ Coil rapid detection system and Petrifilm test kit-HEC for detection of Escherichia coli O157:H7 in fresh and frozen ground beef.

The Difco EZ Coli Rapid Detection System was compared to the 3M Petrifilm method for detection of Escherichia coli O157:H7 in raw ground beef. Raw meatballs (25 g) were inoculated with 10 to 15 cells of Escherichia coli O157:H7, stored for various times and at different temperatures, and then stomached for 2 min in 225 ml of EZ Coli enrichment broth, which was then incubated at 42 degrees C for 18 to 24 h. A 1-ml sample of the enrichment broth was loaded into the top of the detector tips and the remaining EZ Coli broth held at 35 degrees C before streaking onto MacConkey sorbitol agar and tryptic soy agar with yeast extract. A duplicate set of meatballs were tested using the 3M Petrifilm Test Kit-HEC for hemorrhagic Escherichia coli O157:H7. In this method raw meatballs (25 g) were enriched for 6 h in modified EC broth containing novobiocin at 37 degrees C prior to inoculation of the Petrifilm E. coli Count Plates, which were incubated at 42 degrees C for 18 h. The immunoblot ELISA was performed following this incubation. Presumptive positive isolates from both methods were confirmed using Oxoid E. coli Latex Agglutination and Difco Pasco ID Tripanels. Both methods permitted detection of 10 to 15 cells of E. coli O157:H7 per ml (i) immediately following inoculation, (ii) after 3 days of refrigerated storage at 8 degrees C, and (iii) after 30 days in frozen storage at -20 degrees C. The Difco EZ Coli Detection System proved to be a simpler and faster screening method with identification of negative and presumptive positive samples within 15 to 18 h.

The oxidation of naphthalene and pyrene by cytochrome P450cam.

Mutants of the heme monooxygenase cytochrome P450cam in which Y96 had been replaced with hydrophobic residues, have been shown to oxidise naphthalene and pyrene with rates one to two orders of magnitude faster than the wild-type. Naphthalene was oxidised to 1- and 2-naphthol, probably via the 1,2-oxide intermediate. In the case of the Y96F mutant, naphthalene was oxidised at a rate comparable to camphor. Pyrene oxidation gave 1,6- and 1,8-pyrenequinone with no evidence for attack at the K-region, in contrast to mammalian enzymes. The results show that the Y96 residue plays a key role in controlling the substrate range of P450cam.

Halothane relaxes previously constricted human epicardial coronary artery segments more than isoflurane.

To compare the vasodilatory effects of isoflurane versus halothane on coronary arteries in vitro, we studied the capacity of isoflurane and halothane to relax resting and previously constricted human coronary artery segments with use of in vitro tension recording. Human epicardial coronary artery segments (1.5-2.0 mm outside diameter) were obtained from hearts excised from recipient patients at time of heart transplantation. The effects of 0.5%, 1.0%, 2.0%, and 3.0% isoflurane or halothane on resting coronary artery segments stretched to their optimal resting tension were determined. Next, after removal of anesthetic from the bathing solution, the segments were constricted with K+ (60 mM), and this contraction was allowed to plateau. The arteries were then again exposed to isoflurane or halothane at 0.5%, 1.0%, 2.0%, and 3.0% concentrations. Isoflurane and halothane had no effect on noncontracted coronary artery segments stretched to their optimal resting tension. Halothane caused significant relaxation of K(+)-induced (60 mM) contractions at 2.0% and 3.0% but not at lower concentrations. Isoflurane did not cause significant relaxation of K(+)-induced (60 mM) contractions at any concentration studied. Our studies indicate that under the conditions studied, isoflurane at clinically relevant concentrations is not a significant coronary dilator.

Halothane relaxes preconstricted small and medium isolated porcine coronary artery segments more than isoflurane.

To compare the putative vasodilatory effects of isoflurane versus halothane on porcine coronary arteries, we studied the capacity of isoflurane and halothane to relax K(+)-constricted (30 mM) small (0.5-1.0 mm outside diameter [OD]) and medium (1.0-1.5 mm OD) porcine coronary arteries with use of in vitro tension recording. We also examined the effect of the dihydropyridine calcium channel agonist BAY K8644 on previously constricted epicardial porcine coronary artery segments in the presence of halothane or isoflurane. Our purpose was to determine (a) whether anesthetic effect on coronary arteries varied with arterial diameter, and (b) whether halothane and isoflurane inhibited BAY K8644-induced contraction of coronary vessels. Small and medium porcine coronary artery segments were constricted with K+ (30 mM) and the resulting contraction was allowed to stabilize. This was followed by exposure to 0.5%, 1.0%, 2.0%, and 3.0% isoflurane or halothane and the resultant tension was again measured. Potassium-induced contractions were significantly relaxed by halothane in small coronary artery segments at 0.5%, 1.0%, 2.0%, and 3.0% and in medium coronary artery segments at 1.0%, 2.0%, and 3.0%. Potassium-induced contractions were significantly reduced by isoflurane only at 3.0% in both small and medium coronary artery segments. Halothane caused significantly more relaxation of both small and medium porcine coronary arteries previously constricted with K+ (30 mM) than did isoflurane. There were no significant differences in coronary artery response to isoflurane or halothane with respect to coronary artery diameter. These experiments indicate that in porcine coronary arteries greater than 0.5 mm OD, studied in vitro after K(+)-induced contraction, isoflurane was not a potent coronary vasodilator.(ABSTRACT TRUNCATED AT 250 WORDS)

Qualitative and quantitative comparison of the distribution of phosphorylated and non-phosphorylated neurofilament epitopes within central and peripheral axons of adult hamster (Mesocricetus auratus).

The distribution of phosphorylated and non-phosphorylated neurofilament epitopes was determined immunocytochemically in adjacent 2 microns-thick sections of sciatic nerve, ventral root and spinal cord. Staining was scored as either intense, moderate or absent and the proportion of labeled axons was calculated for each category. Nearly all sciatic nerve and ventral root axons were immunoreactive with both antibodies against phosphorylated and non-phosphorylated neurofilaments and there were no significant differences in the number of intensely- or moderately-labeled axons. Within the spinal cord however, while the majority of large caliber axons was stained with both antibodies, there was a significant number of small caliber axons which stained only with antibodies against phosphorylated neurofilaments. These results show that phosphorylated and non-phosphorylated neurofilaments are extensively codistributed in CNS and PNS axons, and that in the CNS, staining intensity for non-phosphorylated epitopes is less in the smaller axons.

Peripheral nerve grafts lacking viable Schwann cells fail to support central nervous system axonal regeneration.

Peripheral nerve grafts were implanted bilaterally into the diencephalon of adult hamsters. One graft segment contained both viable Schwann cells and their basal lamina tubes. The Schwann cell population in the second graft segment was killed by freezing prior to implantation. Seven weeks after graft implantations, the extracranial end of each graft segment was exposed, transected and labelled with a fluorescent tracer substance. One week after the labelling procedure each animal was perfused and the diencephalon and midbrain were examined. Ultrastructural analyses of both types of graft demonstrated the persistence of the Schwann cell-derived basal lamina tubes. Retrogradely labelled neurons were found in all cases in which an intact graft remained in place for two months, but were seen in only one case with a frozen graft. Large numbers of myelinated and unmyelinated axons were seen within the intact grafts, but no axons were found in the previously frozen grafts. These results indicate that lesioned CNS axons are able to regenerate vigorously when provided with an environment which includes viable Schwann cells. But, CNS axons regenerate less well, if at all, when Schwann cells are absent. Further, it appears that Schwann cell-derived basal lamina tubes, when isolated from their parent cells, are insufficient to initiate or sustain CNS axonal regeneration.

Differential distribution of phosphorylated and non-phosphorylated neurofilaments within the retina and optic nerve of hamsters.

Retinae and optic nerve sections from adult hamsters were reacted with antibodies against phosphorylated (P) or non-phosphorylated (NP) neurofilament proteins. NP epitopes were observed within ganglion cell bodies and extended into the proximal portion of the optic nerve. P epitopes became prominent within axons as they approached the optic disc and remained throughout the optic nerve. This spatial distribution appears similar to the pattern of myelination within this axonal population.

Growth of retinal ganglion cell axons following optic nerve crush in adult hamsters.

Regrowth of retinal ganglion cell axons was examined 2 to 60 days after intraorbital optic nerve crush lesions in adult hamsters. Anterograde axonal transport of intraocularly injected wheat germ agglutinin-horseradish peroxidase conjugate was used to label the axons after specific postinjury time periods. Labeled axons were present in the region of the optic nerve lying between the eye and the crush site at all times, but their numbers appeared to decrease with increasing survival time. Labeled axons were first detected in the segment of optic nerve lying distal to the crush site 1 week after injury and had extended as far as 2.3 mm beyond the crush site by 60 days postinjury, growing at a rate similar to that at which the collateral branches of developing ganglion cell axons extend into their targets. Although most axons failed to regrow after these lesions, the slow reextention exhibited by members of a small population of axons indicates that the degenerating adult mammalian optic nerve provides an adequate environment for a particular mode of regrowth by injured axons of the central nervous system.

Embryonic and larval development of the sonic motor nucleus in the oyster toadfish.

The sonic motor nucleus (SMN), a likely homologue of the hypoglossal nucleus, provides the final common pathway for sound production in the oyster toadfish (Opsanus tau). SMN neurons increase in size and number for 7-8 years postnatally, and the swimbladder-sonic muscle complex grows throughout life. This study describes the normal embryonic and larval development of the SMN from its initial differentiation on about day 19 through day 40, when the yolk sac is resorbed and the fish is free swimming. In contrast to the rapid development of CNS nuclei in mammals, the SMN gradually increased in maturity with more active growth at the beginning and end of the observation period and a relatively static period in the middle. Consistent with a hypoglossal homology, the SMN differentiated within the spinal cord, added cells rostrally, and eventually extended into the medulla. Immature neurons appeared to originate from precursor cells in the ventral portion of the ventricular zone of the central canal. Such cells were initially round with little cytoplasmic development and later added processes and Nissl substance. The number of neurons increased 10-fold from a median of 35 to 322 cells, and no evidence of cell death was observed. Soma area approximately doubled from 20.6 to 41.2 micron 2, and cell nucleus area followed a similar pattern. [3H]-thymidine autoradiography demonstrated that neurons were added continuously throughout the nucleus during embryonic and larval development.

Growth of optic tract axons in nerve grafts in hamsters.

Segments of peripheral nerve, transplanted to the brain or spinal cord, recently have been shown to support regeneration of axons from a variety of central neurons. However, long-tract axons, injured at considerable distances from their cell bodies, have proven refractory to such regenerative support. This report presents evidence for successful, although similarly limited, growth of retinal ganglion cell axons into peripheral nerve grafts placed in the optic tract of adult hamsters. The demonstration of such growth allows the possibility that the primary visual pathways may serve as an advantageous model system in which to study the mechanism of graft-effected regeneration of long-tract axons in the adult mammalian central nervous system.

Alterations of the crossed parabigeminotectal projection induced by neonatal eye removal in rats.

Projections of the parabigeminal nucleus to the contralateral superior colliculus and dorsal lateral geniculate nucleus were examined in normal adult pigmented rats and in adult rats from which one or both eyes had been removed at birth. In normal rats the crossed parabigeminotectal projection is restricted to the superficial layers in anterior and medial areas of colliculus, regions innervated also by the lower temporal portion of the ipsilateral retina. In unilaterally enucleated animals the crossed parabigeminotectal projection to the "denervated" colliculus is expanded, as is the retinal projection from the ipsilateral eye. In addition, there is a crossed parabigeminal projection to the "denervated" dorsal lateral geniculate nucleus in these rats. In bilaterally enucleated animals the parabigeminotectal projection is expanded, but not as greatly as in unilateral enucleation cases; there is a crossed parabigeminothalamic projection in these animals as well. The corresponding termination patterns of the contralateral parabigeminal nucleus and the ipsilateral retina in the normal superior colliculus may indicate a functional and/or developmental interdependence between the projections from these two regions. The existence of an expanded parabigeminotectal projection in bilaterally enucleated rats shows that a sustained ipsilateral retinotectal projection is not necessary for the establishment of a crossed parabigeminotectal projection, but points to the possibility that ipsilateral retinal input may constrain the parabigeminal projection to terminate within certain boundaries. The even greater expansion of the projection from the parabigeminal nucleus to the colliculus which receives an expanded projection from the ipsilateral retina of unilaterally enucleated rats suggests that the functional organization of the ipsilateral retinotectal projection may be capable of restricting the size of the terminal field of the crossed parabigeminotectal projection.

Henoch-Schönlein purpura: simultaneous demonstration of IgA deposits in involved skin, intestine, and kidney.

Recent reports indicate that circulating IgA immune complexes may play a primary role in the pathogenesis of Henoch-Schönlein vasculitis and are responsible for the granular deposits of IgA seen in biopsy specimens of skin and kidney. A patient had classic Henoch Schönlein syndrome, including hematuria, purpura, and abdominal pain; tissue taken simultaneously from the small intestine, skin, and kidney was examined by light immunofluorescent, and electron microscopy. Granular deposits of IgA were found in small-vessel walls of the intestinal tissue and skin, and in the glomerular mesangium. This provides further support for the notion that IgA deposits produce tissue injury in intestine, skin, and kidney in Henoch-Schönlein syndrome.

Morphology of radial glia, ependymal cells, and periventricular neurons in the optic tectum of goldfish (Carassius auratus).

There are three populations of cells in the deep layers of the optic tectum in a normal adult goldfish: the periventricular neurons, the ependymal cells, and the radial glia. The characteristic morphological features which distinguish the three cell populations are examined at light and electron microscopic levels in the present work. A radial glial cell has a deeply invaginated nucleus located in a subependymal layer. Its cytoplasm contains mitochondria with 35-nm dark granules and 20-nm microtubules but no intermediate filaments. Its prominent radial process extends through the superficial tectal layers. In contrast, the processes of ependymal cell ramify and interweave within the ependymal region. The cytoplasm of an ependymal cell contains prominent bundles of intermediate filaments but not microtubules. Its soma lies at or near the ventricular surface. A periventricular neuron has a round nucleus and a smooth dendrite which extends toward the superficial tectal layers. Its cytoplasm contains microtubules and agranular mitochondria. Axosomatic and axodendritic synapses are found on periventricular neurons. The morphological characteristics of these cell types are considered in relation to previous descriptions of teleost tectal cytology and with regard to the atypical natures of the cytoskeletal elements of the ependymal and radial glial cells.