Minimum standards of pelvic exenterative practice: PelvEx Collaborative guideline

This document outlines the important aspects of caring for patients who have been diagnosed with advanced pelvic cancer. It is primarily aimed at those who are establishing a service that adequately caters to this patient group. The relevant literature has been summarized and an attempt made to simplify the approach to management of these complex cases.

Improving surgical site infection prevention practices through a multifaceted educational intervention

As part of the National Clinical Programme on healthcare-associated infection prevention, a Royal College of Surgeons in Ireland (RCSI) and Royal College of Physicians of Ireland (RCPI) working group developed a quality improvement tool for prevention of surgical site infection (SS). We aimed to validate the effectiveness of an educational campaign, which utilises this quality improvement tool to prevent SSI in a tertiary hospital. Prior to the SSI educational campaign, surgical patients were prospectively audited and details of antibiotic administration recorded. Prophylactic antibiotic administration recommendations were delivered via poster and educational presentations. Post-intervention, the audit was repeated. 50 patients were audited pre-intervention, 45 post-intervention. Post-intervention, prophylaxis within 60 minutes prior to incision increased from 54% to 68% (p = 0.266). Appropriate postoperative prescribing improved from 71% to 92% (p = 0.075). A multifaceted educational program may be effective in changing SSI prevention practices.

Introduction of oesophageal Doppler-guided fluid management in a laparoscopic colorectal surgery enhanced recovery programme: an audit of effect on patient outcome

Morbidity after colorectal surgery can be reduced with intraoperative oesophageal Doppler monitor (ODM) guided fluid therapy. We audited the effect of introducing ODM-guided fluid therapy in enhanced recovery laparoscopic colorectal surgery. ODM group (n = 40) outcomes (toleration of diet, Post Operative Morbidity Survery (POMS) score, complications) were compared to matched patients (n = 40) who had the same surgery using a conventional approach to fluid management. Mean (SD) time to tolerate diet was shorter in the ODM group (2.3 (1.6) days vs 3.8 (2.4) days, p = 0.003). The ODM group had a lower mean (SD) POMS score on post-operative day 1 (2 (1.4) vs 4 (1.1), p = 0.001), fewer postoperative complications (14 patients vs 20, p = 0.009) and a lower rate of unplanned critical care area admission (1 vs 6, p= 0.001). Introduction of intraoperative ODM-guided stroke volume optimization was associated with improved outcomes in patients undergoing enhanced recovery laparoscopic colorectal surgery.

Epidemiology of Burkitt's lymphoma in Northwest Province, Cameroon, 2003-2010

BACKGROUND

Burkitt's lymphoma (BL) is an aggressive non-Hodgkin's lymphoma endemic to regions of Africa. Cases are thought to be typically found in low-lying, humid regions where malaria is rife.

AIMS AND OBJECTIVES

To investigate the clinical characteristics of BL, its incidence and relationship with malarial incidence in Northwest (NW) Province, Cameroon.

METHODS

Data on BL were collected from the three tertiary referral centres for BL treatment in NW Province, Cameroon. Data on malaria were collected from the Delegation of Public Health in Bamenda, NW Province. Data were collected between March and May 2010.

RESULTS

471 cases of BL were identified. The St Jude's stage of patients at presentation was as follows: stage I, 14.4% (43/299); stage II, 8.4% (25/299); stage III, 69.9% (209/299); stage IV, 7.4% (22/299). The incidences of BL per 100,000 children <15 years of age from 2005 to 2009 were as follows: 2005, 3.01 (29); 2006, 2.02 (20); 2007, 2.45 (25); 2008, 2.38 (25); 2009, 3.06 (33). The average incidence in NW Province was 2.58. In the Ndop plain, Ngo-Ketunjia, the incidences of BL were as follows: 2005, 10.3 (10); 2006, 3.00 (3); 2007, 1.95 (2); 2008, 2.84 (3); 2009, 4.60 (5). The average incidence was 4.54/100,000 children <15 years of age. Statistical analysis demonstrated a sinusoidal distribution of malaria cases throughout the year (P<0.00), with a peak incidence on 10 April. Conversely, no sinusoidal distribution of BL cases was demonstrated throughout the year (P = 0.09).

CONCLUSION

No relationship was demonstrated between an acute malarial infection and BL. Significant clustering was found, with the low-lying Ndop plain of Ngo-Ketunjia having an incidence of BL nearly twice that elsewhere in the region. The study demonstrates that the incidence of BL in NW Province, Cameroon remains one of the highest documented in the world.

The Cameroon 2008 Burkitt lymphoma protocol: improved event-free survival with treatment adapted to disease stage and the response to induction therapy

Treatment of endemic Burkitt lymphoma (BL) with cyclophosphamide (CPM) and intrathecal methotrexate (IT MTX) can cure 50% of patients. In this study, induction therapy with CPM and IT MTX was followed by consolidation chemotherapy adapted for stage, clinical response, and abdominal ultrasound findings. One hundred and twenty-nine consecutive patients with BL, 77 male and 52 female with a median age of 7.9 years, were treated in mission hospitals in Cameroon. The diagnosis rested on fine-needle aspirate (79%), biopsy, bone marrow, cerebrospinal fluid, abdominal ultrasound, and clinical examination. Six percent had St Jude stage I, 13% stage II, 72% stage III, and 12% stage IV disease. The abdomen (76%) and face (50%) were mainly involved. Induction chemotherapy was CPM 40 mg/kg and IT MTX 12.5 mg and IT hydrocortisone 12.5 mg on days 1, 8, and 15. Stage I and II patients received CPM 60 mg/kg on day 29, and stage III patients CPM 60 mg/kg on days 29 and 43 if in remission on day 28. Stage IV patients and patients not in remission received CPM 60 mg/kg on days 29, 43, and 57 and 1.0 g/m(2) MTX intravenous (IV) and vincristine 1.5 mg/m(2) IV on day 29. Event-free survival (EFS) at mean 365 days was 61% (n = 79) and 100% in stage I, 85% in stage II, 60% in stage III, and 27% in stage IV patients. Deaths (n = 24) were disease or treatment related and 26 patients relapsed (mean 135 days). Risk-adapted treatment achieved 61% 1-year EFS.

Metastatic paediatric colorectal carcinoma

A 16-year-old girl presented to our unit with crampy abdominal pain, change in bowel habit, a subjective impression of weight loss and a single episode of haematochezia. She was found to have a rectosigmoid adenocarcinoma and proceeded to laparoscopic anterior resection, whereupon peritoneal metastases were discovered. She received chemotherapy and is alive and well ten month later with no radiological evidence of disease. Colorectal carcinoma is rare in the paediatric population but is increasing in incidence. Early diagnosis is critical to enable optimal outcomes.

The incidence, clustering and characteristics of Burkitt lymphoma in the Northwest province of Cameroon

The epidemiology of Burkitt lymphoma (BL) has never been documented in Cameroon. Data were collected from 16 hospitals, the Delegation of Public Health and the regional pathologist in the Northwest province of Cameroon on all BL cases. The incidence of BL in this region is 5.9/100,000 children aged <15 years/year – the second highest incidence documented to date. Significant clustering was also identified in Ndop, a low-lying region with a high malaria endemicity, at 21.5 cases/100,000 children aged <15 year/year ( P < 0.001).

Semen quality in captive Houbara bustard, Chlamydotis undulata undulata

Semen quality in captive-bred Houbara bustards, Chlamydotis undulata undulata, was assessed during three consecutive breeding seasons. In any one season, sperm quality, in terms of the proportion of eosin-permeable spermatozoa and of spermatozoa with abnormally large nuclei, varied among individual males, but not among their ejaculates. Neither the proportion of spermatozoa with large nuclei, nor those permeable to eosin were related to the total sperm output of males. The fertilizing ability of males was related to their mean seasonal proportion of eosin-permeable spermatozoa, but not the proportion of spermatozoa with large nuclei. The ranking of males on the basis of the proportion of spermatozoa with large nuclei in their ejaculates was significantly positively correlated between seasons, although ranking on the basis of sperm eosin-permeability was not. The cause or consequence of producing spermatozoa with large nuclei (and excess DNA) remains to be elucidated, but appears to be a trait that is characteristic of houbara bustard males that is maintained between breeding seasons.

Immune function, telomerase, and angiogenesis in patients with primary, operable nonsmall cell lung carcinoma: tumor size and lymph node status remain the most important prognostic features

BACKGROUND

Lung carcinoma usually is advanced at the time of presentation and frequently shows metastatic spread. In recent times, prognostic factors such as c-erbB-2 in patients with breast carcinoma have provided useful information and beneficial therapeutic targets. The objective of this study was to evaluate angiogenesis, immune function, and telomerase expression in patients with nonsmall cell lung carcinoma (NSCLC) to determine their prognostic significance.

METHODS

Immunohistochemistry was used to evaluate the expression of human telomerase reverse transcriptase (hTERT; n = 115 patients), interleukin-2r (IL-2r; n = 40 patients), microvessel density (MVD; n = 81 patients), and vascular endothelial growth factor (VEGF; n = 61 patients). Three-year survival follow-up information was available for most patients, and a comprehensive review of clinicopathologic features was carried out.

RESULTS

Fifty percent of tumors showed nuclear staining for hTERT, 55% of tumors showed some degree of lymphocyte IL-2r expression, 33% of tumors were recorded with an MVD that was higher than average, and VEGF staining was detected in 85% of tumors. None of the parameters measured had an impact on survival. hTERT expression was correlated with lymph node status. Lymph node status and tumor size were identified as independent prognostic factors.

CONCLUSIONS

This study failed to identify a marker of prognosis for patients with NSCLC other than tumor size and lymph node status in this population. Telomerase expression was associated with metastases, raising the possibility that this enzyme is involved in the metastatic process. Tumor cell VEGF expression was identified frequently: This growth factor may have potential as a target for antiangiogenic therapy. Lung carcinoma typically is the result of large numbers of mutations. Further understanding of the biologic implications of these mutations will lead to the development of effective prognostic markers and treatments for patients with NSCLC.

Immune function, telomerase, and angiogenesis in patients with primary, operable nonsmall cell lung carcinoma: tumor size and lymph node status remain the most important prognostic features

BACKGROUND

Lung carcinoma usually is advanced at the time of presentation and frequently shows metastatic spread. In recent times, prognostic factors such as c-erbB-2 in patients with breast carcinoma have provided useful information and beneficial therapeutic targets. The objective of this study was to evaluate angiogenesis, immune function, and telomerase expression in patients with nonsmall cell lung carcinoma (NSCLC) to determine their prognostic significance.

METHODS

Immunohistochemistry was used to evaluate the expression of human telomerase reverse transcriptase (hTERT; n = 115 patients), interleukin-2r (IL-2r; n = 40 patients), microvessel density (MVD; n = 81 patients), and vascular endothelial growth factor (VEGF; n = 61 patients). Three-year survival follow-up information was available for most patients, and a comprehensive review of clinicopathologic features was carried out.

RESULTS

Fifty percent of tumors showed nuclear staining for hTERT, 55% of tumors showed some degree of lymphocyte IL-2r expression, 33% of tumors were recorded with an MVD that was higher than average, and VEGF staining was detected in 85% of tumors. None of the parameters measured had an impact on survival. hTERT expression was correlated with lymph node status. Lymph node status and tumor size were identified as independent prognostic factors.

CONCLUSIONS

This study failed to identify a marker of prognosis for patients with NSCLC other than tumor size and lymph node status in this population. Telomerase expression was associated with metastases, raising the possibility that this enzyme is involved in the metastatic process. Tumor cell VEGF expression was identified frequently: This growth factor may have potential as a target for antiangiogenic therapy. Lung carcinoma typically is the result of large numbers of mutations. Further understanding of the biologic implications of these mutations will lead to the development of effective prognostic markers and treatments for patients with NSCLC.

Chronic inflammatory bowel disease and the 'over-clean' environment: rarity in the Irish 'traveller' community

The causes of ulcerative colitis and Crohn's disease are unknown. Current research is focused on genetic factors but environmental factors may also be important. Exposure to infections in early life is believed to reduce the incidence of bronchial asthma. We hypothesised that exposure to enteric bacteria and infections in early life may also reduce the incidence of idiopathic inflammatory bowel disease. Chronic inflammatory bowel disease may be a by-product of our over-clean environment. Social groups with poorer living standards might be expected to have a lower prevalence of this condition. The "traveller" or itinerant community in Ireland is one such group. We therefore attempted to estimate the prevalence of inflammatory bowel disease in the traveller population. Twenty five of 30 gastroenterologists or surgeons in Ireland responded to requests for information. None could recall ever seeing a "traveller" with idiopathic inflammatory bowel disease. While genetic factors cannot be excluded, a low prevalence of idiopathic inflammatory bowel disease would support the environmental hypothesis.

Variability in the size of the nucleus in spermatozoa from Houbara bustards, Chlamydotis undulata undulata

Semen collected from 3-year-old male Houbara bustards contained large proportions (6-40%) of spermatozoa with large nuclei. In these spermatozoa, the length of the nucleus was up to twice the mean length of the nucleus in normal spermatozoa. The lengths of the acrosome, midpiece and flagella were all normally distributed, but the length of the nucleus formed a bimodal distribution. The proportion of spermatozoa with large nuclei varied among males, but not among different semen samples collected from the same male throughout the breeding season. The proportion of motile spermatozoa with large nuclei was half that of normal spermatozoa, but their velocity was significantly greater. After insemination into females, spermatozoa with large nuclei were observed in the outer perivitelline layer of eggs laid, indicating that they were stored and transported within the oviduct and reached the egg at about the time of fertilization. Furthermore, there was no difference in the ability to produce viable progeny in females that were mated with males producing greater proportions of spermatozoa with large nuclei compared with those producing 'normal' spermatozoa. Thus, the abnormal spermatozoa did not appear to impede fertility. There were no signs of triploidy in the males that produced spermatozoa with large nuclei, or in their progeny, as demonstrated by the size of erythrocytes. Therefore, it appears that the spermatozoa with large nuclei were the result of aberrant spermatogenesis.

Quality of life of candidates for and recipients of heart transplants

OBJECTIVE

To describe the quality of life (QOL) of candidates for and recipients of heart transplants over a five-year period.

DESIGN

Descriptive, longitudinal.

SETTING

Canadian university-affiliated tertiary care medical centre.

PATIENTS

Sixty-five candidates for heart transplantation; after one year, six candidates were still awaiting transplantation; 42 patients received transplants and were included in the study six months post-transplant.

OUTCOME MEASURES

Three measures of QOL were used: the Index of Well-Being, Cantril's Self-Anchoring Striving Scale and the "time-trade-off technique'.

INTERVENTION

Data were collected before transplantation, six months post-transplantation, one year post-transplantation and annually for the next four years; for individuals who did not receive transplants, data were collected six months and one year after the first interview.

MAIN RESULTS

QOL scores were considerably higher after than before transplantation, and compared favourably with norms for the general population. For 11 individuals who did not receive transplants, QOL remained low. QOL for heart transplant recipients was remarkably stable over the five-year study period. The major predictors of QOL for candidates awaiting transplantation were health status, outlook and ability to work. After transplantation, the major predictors of QOL were outlook, health status and employment status.

CONCLUSIONS

There is evidence to suggest that QOL improves after heart transplantation, and that improvement is relatively stable over time. Further work is needed to identify the factors that could result in improvements in QOL.

Intraoperative monitoring of motor evoked potentials: a review of 116 cases

We reviewed the results of motor evoked potential (MEP) and somatosensory evoked potential (SEP) monitoring during 116 operations on the spine or spinal cord. We monitored MEPs by electrically stimulating the spinal cord and recording compound muscle action potentials from lower extremity muscles and monitored SEPs by stimulating posterior tibial or peroneal nerves and recording both cortical and subcortical evoked potentials. We maintained anesthesia with an N2O/O2/opioid technique supplemented with a halogenated inhalational agent and maintained partial neuromuscular blockade using a vecuronium infusion. Both MEPs and SEPs could be recorded in 99 cases (85%). Neither MEPs nor SEPs were recorded in eight patients, all of whom had preexisting severe myelopathies. Only SEPs could be recorded in two patients, and only MEPs were obtained in seven cases. Deterioration of evoked potentials occurred during nine operations (8%). In eight cases, both SEPs and MEPs deteriorated; in one case, only MEPs deteriorated. In four cases, the changes in the monitored signals led to major alterations in the surgery. We believe that optimal monitoring during spinal surgery requires recording both SEPs and MEPs. This provides independent verification of spinal cord integrity using two parallel but independent systems, and also allows detection of the occasional insults that selectively affect either motor or sensory systems.

Identification of exons in a novel embryonal carcinoma locus using the GRAIL program

Embryonal carcinoma (EC) cells have proven to be of particular value in studies of both oncogenesis and mammalian development, as well as in evaluating the relationship between these two phenomena. Infection of the EC cell line, NR1-0, with a defective retrovirus containing a neomycin resistance cassette (Neo(r)), produced a mutant cell line: NR1-6. Genetic analysis of this variant cell line indicates that there is only a single insertion site. Interestingly, however, the NR1-6 cell line is unique in its morphology, tumorigenicity, and differentiative potential (1). We have sequenced over 18 kb from the regions flanking the retroviral insertion which we then analyzed using the computer programs GCG and BLAST. Although homology was found to 4 B1 repeat elements (approximately 150 bp long) and a novel CA/GT dinucleotide repeat, no homology was found to any known genes (2). Furthermore, attempts to identify potential exons or transcripts using various molecular techniques and the above mentioned computer programs were all negative. Most recently we employed the GRAIL (Gene Recognition and Analysis Internet Link) computer program which was specifically designed to identify potential exons (3). Analysis with this program identified 5 exon candidates: two characterized as excellent (>90% probability) and three as marginal (>60% probability). Using reverse transcriptase (RT)-PCR we have demonstrated that the two 'excellent' and one of the 'marginal' exon candidates identified by GRAIL are expressed as mRNA in the mutant cells. Sequencing of these PCR products indicates that the mRNA is identical to the genomic DNA sequence. Thus, we have found that GRAIL provides an efficient, reliable means of identifying real exons within long regions of novel genomic DNA.

Novel mouse repetitive element structures in an embryonal carcinoma mutant cell line

A mutant embryonal carcinoma (EC) cell line, NR1-6, has been isolated subsequent to infection with a retroviral insert containing a neomycin resistance cassette (Neo(r)) (1). This variant cell line has only a single insertion site, but is unique in its morphology, tumorigenicity, and differentiative potential (2). In order to understand the exact nature of the mutational event, we have sequenced the regions immediately flanking the insertion site (encompassing over 18 kb). Searches for homology in GenBank using the GCG and Blast programs have revealed homology to only a few small conserved regions (4 B1 repetitive elements approximately 150 bp long and a CA/GT dinucleotide repeat). Interestingly, B1 repetitive elements have been reported to play a role in germ cell differentiation. One of these elements is immediately 5' upstream of the insertion site and it appears as if the retroviral insertion may be responsible for activating or repressing the expression of this element. The CA/GT repeat has not yet been mapped within the mouse genome. Thus, we have identified a novel mouse locus which apparently regulates a number of cellular phenotypes.

Analysis by somatic-cell fusion of the phenotypic properties of a mutant embryonal carcinoma cell-line

We have previously reported the isolation of an embryonal carcinoma (EC) cell mutant created via retroviral insertion (1). The mutant (NR1-6) is aberrant in respect to morphology, tumorigenicity and response to retinoic acid (RA). In order to determine the dominance/recessive hierarchy and genetic relationships of these phenotypes, we created hybrid lines from mutant and parental cells. Three hybrid clones (Hyb 1, 2a and 2b), which retain both mutant and parental loci, were analyzed. Our results indicate that in all parameters - morphology, adhesion, qualitative and quantitative response to RA and tumorigenicity - the hybrids behave similarly to parental cells. In no case did any of the hybrid lines exhibit a mutant phenotype. The data indicate that the phenotypes we have studied are genetically interrelated and that the parental characteristics are dominant.

A comparative-analysis of the activity of retinoic Acid and cyclic-amp in the induction of differentiation of embryonal carcinoma-cells

Retinoic acid (RA) and/or cAMP elevating agents have been shown to promote differentiation of embryonal carcinoma (EC) cells. In this report we examine the response of different EC cell lines to different combinations of RA and cAMP elevating reagents. The degree of differentiation was measured via mRNA levels of stage specific markers: Endo A, collagen IV and tissue plasminogen activator. We show that complete differentiation cannot be achieved with cAMP elevating agents alone. Furthermore, the results obtained with each cell line are quite distinct and the degree of differentiation differs with the type of cAMP elevating agent used and the marker examined.

Parents' developmental perceptions and expectations for their high-risk infants

This study examines the relationship between developmental outcomes of high-risk infants and parental perceptions and expectations. Parents of 209 consecutive high-risk infants were asked to provide their development interpretations and expectations before their infants received standard developmental assessments between April and October 1989. Moderate correlations between parents and professional assessments of motor and language skills were noted (p less than .05 to p less than .01). Most agreements occurred when infants were assessed as normal by professionals. Disagreements were common and occurred in all areas of development. These mismatches were not associated with gestational age at birth, neonatal complications, poverty, or estimates of parental experience. Professionals should take seriously any expressed developmental concerns by parents of high-risk infants. Expressed developmental concerns, however, cannot be relied on for developmental screening of high-risk infants.

Covert visual orienting: hemifield-activation can be mimicked by zoom lens and midlocation placement strategies

How is attention distributed over visual space when an observer expects a target to occur at one of several possible locations? Two experiments sought to understand the source of the conflict between studies leading to the notions of hemifield activation (Hughes and Zimba 1985) and attentional gradients (Downing and Pinker 1985; Shulman et al. 1985, 1986). subjects were cued to attend one of the 4 corners of an imaginary square centered at fixation, allowing comparison of uncued locations in the cued and uncued hemifields. In one experiment marking of the 4 locations was varied to determine if providing a 'target' for attention is necessary to obtain within-hemifield gradients. RT was faster at the cued location than at the three uncued locations which had equivalent latencies, a pattern that was unaffected by marking of the potential target locations. This result, which is consistent with the notion of a gradient around the attended location is a strong disconfirmation of the hemifield activation hypothesis. The second experiment demonstrated that an unusual procedure for presenting the probe stimuli in Hughes and Zimba (1985) is at least partially responsible for their evidence for uniform hemifield activation. It is proposed that visual attention is directed to visuo-spatial channels with fixed structural properties, and that when attention to two locations is desired, the subject may attend a spatial channel located between them.

Reduced fertility in women with X chromosome abnormality

One patient with the karyotype 46,X,del(X)(p11.23) and three patients with 45,X/46,XX mosaicism were fertile or showed normal ovarian function. The patient with the Xp deletion has two daughters with the same chromosomal abnormality. A study of these patients and of others reported in the literature indicated that fertility of patients with X chromosomal abnormality has a markedly shorter duration than fertility of the normal female. Menopause commonly occurred during the second and third decade of age. We suggest that such fertility is related to the rate of germ cell attrition and hypothesize that germ cell attrition in the human female is influenced by genes of multiple effect which are carried on the X chromosome. The more of these genes which are present the slower the rate of germ cell attrition.

A class of large polysaccharides contains the antigenic determinants for the cytotoxic antibodies in a conventional syngeneic anti-F9 serum as well as a monoclonal antibody prepared against F9 cells

The molecular natures of the antigenic targets detected by cytotoxic antibodies in both a monoclonal antibody (ECMA-3) made against F9 cells and a conventional mouse anti-F9 serum were investigated. Both of the antibodies precipitated a class of high molecular weight polysaccharides from Nonidet P40 lysates of F9 cells. These molecules were labeled by radioactive galactose and fucose but only poorly by amino acids; in addition, they were fairly resistant to pronase and the digest still had a molecular weight of 70 K or more. Even after extensive pronase digestion the polysaccharides inhibited the cytotoxic activities of the antibodies, suggesting that the antigenic targets reside on the carbohydrate portion. This class of polysaccharides was shown to be a minor component of the characteristic large polysaccharides of F9 cells.

Cis-trans test shows a functional relationship between non-allelic lethal mutations in the T/t-complex

Recessive lethal mutations in the T/t-complex of the mouse characteristically show defective genetic complementation, even when they affect very different stages of embryogenesis and are known to be nonallelic. To address the question of their genetic or functional relationship, we have applied the cis-trans test, using several well defined recombinant t-chromosomes that carry two or more lethal mutations, and others that are devoid of specific lethals. We show here that the defective complementation that occurs between different t-lethals is a specific result of the trans configuration; thus these genes, which may map as much as 15 cM apart, constitute a functional unit. Some speculations are presented to interpret this enigma in terms of DNA plasticity.

Gene mapping within the T/t complex of the mouse. I. t-Lethal genes are nonallelic

The t haplotypes of mouse chromosome 17 are natural polymorphisms in wild populations that contain mutations that affect or control such diverse functions as tail length, embryonic lethality and maturation and function of male germ cells. The major impediment to dissecting the genetics of this complex region has been its unusual property of recombination suppression in heterozygotes with wild-type chromosomes. Recently it was shown that recombination suppression does not occur in heterozygotes containing two different t haplotypes, which suggested that t chromosomes may be mismatched with respect to wild-type but share sequences that permit crossing-over between them. Thus for the first time questions of allelism and map positions of the t-lethal mutations can be addressed. We report here the results of three experiments that analyzed the tw12 haplotype trans to either tw5, tw32 or tw18. In all cases these lethal mutations were nonallelic to tw12. These results, together with evidence for functional relatedness, suggest the t-lethals may be a gene family spread out over more than 15 centiMorgans of chromosome 17.

Human intestinal potential difference: recording method and biophysical implications

1. The transmural electrical potential difference (PD) of the intact human small intestine was recorded with close attention to electrical symmetry, shielding from electro-magnetic waves and correction for junction potentials. 2. The PD is -12 mV (mucosa-negative) in the fasting jejunum and ileum and does not change during perfusion with isotonic NaCl. 3. Absorption of Na and Cl appears to be non-electrogenic and the 'resting' PD is probably generated by active anion secretion of fasting intestinal contents. 4. Diffusion potentials during isotonic D-mannitol perfusion indicated higher cation selectivity in the ileum than in the jejunum. 5. The calculated contribution of a free-solution path to total paracellular permeability is 55% in the jejunum but only 15% in the ileum. 6. No 'streaming' potential was detected during osmotic water flow, suggesting that the cation-selectivity of the channels is temporarily inactivated during dilatation of the lateral intercellular space.

The incidence of contrast medium induced acute tubular necrosis following arteriography

Twenty-one patients slated for high-dose arteriography were studied to investigate the impact of predisposing medical conditions upon contrast medium induced acute renal failure. The study suggests that predisposing medical conditions are the most important factor determining the incidence of acute renal failure and the probability, speed, and degree of recovery of renal function. Patients with diabetes mellitus incur the highest risk of contrast medium induced acute renal failure. A dose relationship is also suggested. Contrast medium doses containing more than 100 g of iodine uniformly produced acute tubular necrosis in patients with predisposing medical conditions. Conversely, contrast medium doses containing less than 80 g of iodine produced clinically manifest acute renal failure in only one of 14 patients with predisposing medical conditions. Subclinical levels of acute renal failure were recognized in a large number of patients by routine measurement of radionuclide filtration fractions, serum creatinine levels, and urine osmolality and sodium concentration.