Studies of the HLA system and insulin-dependent diabetes mellitus

The relationship between the HLA system and insulin-dependent diabetes mellitus (IDDM) is reviewed. Data compiled by the HLA and Disease Registry reveal that HLA-B8 and/or Dw3 are associated with IDDM in all populations studied so far, but further population studies in non-Caucasian populations should be performed. In Caucasians, HLA-Dw2 renders protection against IDDM while HLA-Dw3 and Dw4 are associated with susceptibility to IDDM. The exact mode of inheritance of susceptibility to IDDM remains to be established. Involvement of at least two genes is likely. Heterogeneity of IDDM is highly possible and should be a matter of major interest in diabetes research.     

In vitro comparison of terbinafine and itraconazole against Penicillium marneffei

We evaluated terbinafine and itraconazole against 30 isolates of Penicillium marneffei using a modification of the National Committee for Clinical Laboratory Standards broth macrodilution MIC testing protocol for yeasts. The minimal fungicidal concentration (MFC) was determined by plating 100 microl from each MIC drug dilution having no growth onto Sabouraud glucose agar incubated at 30 degrees C. The MFC was the dilution at which growth was absent at 72 h of incubation. The MICs, in micrograms per milliliter, were as follows: terbinafine, 0.03 to 1.0 (geometric mean titer, 0.09); itraconazole, 0.03 to 0.5 (geometric mean titer, 0.04). The MFCs, in micrograms per milliliter, were as follows: terbinafine, 0.03 to 8 (geometric mean titer, 2.60); itraconazole, 0.03 to 8 (geometric mean titer, 2. 45). Primary fungicidal activity (MFC within 2 dilutions of MIC) was observed with terbinafine in eight isolates and with itraconazole in four isolates. The data indicate that terbinafine is active against P. marneffei in vitro and may have a previously unrealized role in the management of infections caused by this fungus.     

Using genome-wide measures of coancestry to maintain diversity and fitness in endangered and domestic pig populations

Conservation and breeding programs aim at maintaining the most diversity, thereby avoiding deleterious effects of inbreeding while maintaining enough variation from which traits of interest can be selected. Theoretically, the most diversity is maintained using optimal contributions based on many markers to calculate coancestries, but this can decrease fitness by maintaining linked deleterious variants. The heterogeneous patterns of coancestry displayed in pigs make them an excellent model to test these predictions. We propose methods to measure coancestry and fitness from resequencing data and use them in population management. We analyzed the resequencing data of Sus cebifrons, a highly endangered porcine species from the Philippines, and genotype data from the Pietrain domestic breed. By analyzing the demographic history of Sus cebifrons, we inferred two past bottlenecks that resulted in some inbreeding load. In Pietrain, we analyzed signatures of selection possibly associated with commercial traits. We also simulated the management of each population to assess the performance of different optimal contribution methods to maintain diversity, fitness, and selection signatures. Maximum genetic diversity was maintained using marker-by-marker coancestry, and least using genealogical coancestry. Using a measure of coancestry based on shared segments of the genome achieved the best results in terms of diversity and fitness. However, this segment-based management eliminated signatures of selection. We demonstrate that maintaining both diversity and fitness depends on the genomic distribution of deleterious variants, which is shaped by demographic and selection histories. Our findings show the importance of genomic and next-generation sequencing information in the optimal design of breeding or conservation programs.The main goal in population management is to maintain the most genetic diversity to maximize the survival potential of the population, as well as to potentially select variants that have fitness consequences (Frankham et al. 2002). Conservation programs usually use small numbers of breeding individuals, and thus, genetic variation can decrease rapidly. In commercial breeding programs, artificial selection can lead to a reduction in overall diversity and an increase in inbreeding (Lush 1946). This can have highly detrimental consequences if breeds lose their ability to adapt to different environmental conditions or if deleterious variants are linked to selected loci. Conservation and commercial breeding programs, therefore, are not so different in their approach of managing their populations, although their ultimate goals differ. Inbreeding depression (Charlesworth and Charlesworth 1987) is a common phenomenon in captive populations of many wild species like wolves (Laikre and Ryman 1991) and also in many breeds of domesticated species like dogs (Leroy 2011; O''Neill et al. 2014). Thus, breeders are aware of the need to maintain diversity while also preserving genetic variants that confer desired, distinct phenotypes.For this purpose, controlling the inbreeding rate and, therefore, optimizing the effective population size, is required. Currently, the best known method to achieve these goals is optimal contributions (OC). This method determines the number of offspring that each individual of the current population should contribute to the next generation so as to minimize global coancestry (Ballou and Lacy 1995; Meuwissen 1997; Grundy et al. 1998). Relatedness, i.e., coancestries between individuals, is needed to apply OC in any management program. Traditionally, genealogical coancestries were used when OC were first proposed because marker data were scarce (Ballou and Lacy 1995). Currently, OC based on molecular coancestry is the best way to maintain the most diversity in terms of heterozygosity, provided genotypes are of high density (de Cara et al. 2011; Gómez-Romano et al. 2013). However, management of populations using OC with molecular coancestry may lead to a fitness decrease, since deleterious alleles linked to the markers used to measure coancestry will be maintained (de Cara et al. 2013a). Recently, a measure of coancestry based on shared genomic regions has been proposed as a compromise to maintain both fitness and genetic diversity when the population in the program has a medium to high inbreeding load (de Cara et al. 2013b). One of the aims of this approach is to avoid the occurrence of long runs of homozygosity (ROH) in the offspring, which are characteristic of reduced diversity, due either to selection or bottlenecks and therefore, may confer inbreeding depression (Keller and Waller 2002; Szpiech et al. 2013; Curik et al. 2014). Determining the occurrence of segments of identity by descent (IBD) in potential parents, thereby measuring their relatedness and coancestry, can be used to minimize the occurrence of ROHs in the offspring.Predictions for management based on genealogical, molecular, or IBD segments have been made with simulated data (de Cara et al. 2013b), but have so far not been tested with actual genotype data. Pigs are an excellent model for testing the use of genetic data in population management. Various molecular data sources are available, like a high-quality genome reference (Groenen et al. 2012) and genotyping arrays (Ramos et al. 2009). Pedigree information is also available for a variety of breeds and other captive populations. Pigs display a high degree of heterogeneity in the occurrence of ROHs (Bosse et al. 2012), which to a large extent reflects differences in their demographic histories. The domesticated pig Sus scrofa consists of many commercial breeds that are under strong artificial selection for commercial traits. Although this particular species is widespread in captivity as well as in the wild, other pig species within the genus Sus only occur on a few islands in Southeast Asia and are critically endangered, like the Visayan warty pig Sus cebifrons (Larson et al. 2005, 2007; Groves 2008). Breeding programs for S. cebifrons in zoos have been set up to maintain the species at least in captivity.Here, we combine pedigree information, genotype data, and next-generation sequencing data to perform in silico management of two pig populations with distinctly different histories: a commercially maintained population of the Pietrain breed of S. scrofa; and a captive zoo population of the critically endangered S. cebifrons species. By comparing the decay of heterozygosity over 10 generations, we assess which of three management strategies maintains the most diversity. These strategies are based on (1) genealogical coancestry; (2) molecular marker-by-marker coancestry; or (3) shared regions of the genome. As S. cebifrons is known to have undergone recent bottlenecks that have led to establishing the conservation programs for this species in captivity, we infer the demography of Sus cebifrons to determine the effect of population-specific demography on the management outcome. On the other hand, to understand the effect of the management strategy on ongoing selection in the population, we identify signatures of selection in the Pietrain breed before and after management. Thus, we investigate whether the best strategy is sensitive to demographic history or initial patterns of variation in the population and how this information is relevant to conservation practitioners; and by analyzing signatures of selection, we address whether any of the management strategies may interfere with selection goals by erasing these signatures. Finally, by predicting fitness based on deleterious variants in the genome in both populations, we show the performance of each of these management strategies not only on diversity but also on fitness because ignoring the latter could lead to the accumulation of deleterious variants, loss of viability, and potentially to extinction of the population in a conservation program.     

Characterization of a cloned repetitive DNA sequence concentrated on the human X chromosome.

A tandemly repeated DNA sequence organized predominantly, if not entirely, in a specific manner on the human X chromosome has been cloned in pBR322 and characterized. The sequence was detected as a 2-kilobase band in ethidium bromide-stained agarose gels of BamHI-digested total human nuclear DNA. Although in situ hybridization of the cloned sequence to human metaphase chromosomes showed a single major site of hybridization at the centromere region of the X chromosome and minor sites of hybridization at several autosomal centromeres, Southern blot analysis of restricted total human DNA indicated that the cloned probe is related to other repeated DNAs, particularly the human alphoid DNAs. Restriction enzyme analysis of the cloned fragment revealed an internal repeat structure based upon multiples of 170 base pairs, confirming this relatedness. All available data, however, suggest that the 2-kilobase spacing of BamHI sites within the repeat may be specific to the X chromosome.     

T-cell subset alterations and lymphocyte responsiveness to mitogens and antigen during severe primary infection with HIV: a case series of seven consecutive HIV seroconverters

Seven consecutive patients who presented with a severe acute mononucleosis-like illness associated with HIV seroconversion were evaluated by T-cell subset enumerations and measurements of lymphocyte transformation responses to mitogens and antigen during both their primary illness and a 1-year follow-up period. We observed a characteristic pattern of response to primary HIV infection; initial lymphopenia was followed by CD8 lymphocytosis and inversion of the CD4:CD8 ratio. During follow-up, the CD8 count gradually returned to normal, whereas the CD4:CD8 ratio remained inverted because of a relatively low number of CD4 lymphocytes. Primary infection was followed by prolonged and severe cellular hyporesponsiveness to both mitogens and antigen. At the last follow-up, responses to pokeweed mitogen were still severely impaired, with a median 19% (range 7-50%) of that observed in healthy controls. We conclude that severe primary HIV infection may be followed by sustained lymphocyte hyporesponsiveness, a sustained low percentage of CD4 lymphocytes and sustained inversion of the CD4:CD8 ratio.     

Autoimmunity and extranodal lymphocytic infiltrates in lymphoproliferative disorders

Abstract. Jønsson V, Wiik A, Hou-Jensen K, Christiansen M, Ryder LP, Madsen HO, Geisler C, Hansen MM, Thomsen K, Vorstrup S, Svejgaard A (Rigshospital, University of Copenhagen and State Serum Institute, Copenhagen, Denmark). Autoimmunity and extranodal lymphocytic infiltrates in lymphoproliferative disorders. J Intern Med 1999;  245 : 277–86. Objective. To examine the relationship between autoimmunity and extranodal lymphocytic infiltrates in different lymphoproliferative disorders with immunoglobulin alterations. Subjects and design. A clinical review combined with a retrospective cohort study of 380 patients, 28 with monoclonal gammopathy of undetermined significance, three with common variable immunodeficiency, 147 with chronic lymphocytic leukaemia, 57 with Waldenström's macroglobulinaemia and 145 with non-Hodgkin's malignant lymphoma. Setting. A university hospital and The State Serum Institute in Copenhagen. Intervention. Clinical examination of each patient with special attention to chronic inflammatory and autoimmune manifestations. Biopsies were taken from non-infectious infiltrates, some of which were additionally tested with PCR analysis for gene rearrangements. Serological screening with a test battery for various autoantibodies was used in combination with techniques for the detection of M-components and monoclonal B-cell proliferation. Main outcome measures. Clinical and/or serological autoimmune manifestations, M-component and other immunoglobulin alterations, and inflammatory tissue changes were studied in patients with chronic inflammatory, polyclonal or oligoclonal pseudolymphomas and in monoclonal, malignant extranodal lymphomas. Results. In 380 consecutive patients, 49 (12.9%) had extranodal manifestations, of whom 47 also had autoimmune manifestations. Nearly half of the 47 patients had more than one autoimmune manifestation. There was a strong correlation between clinical signs and corresponding autoantibodies such as anti-SSA and -SSB antibodies in Sjögren's syndrome (10 cases), antithyroid peroxidase antibodies in thyroiditis and Graves' disease (10 cases), and parietal cell antibodies in gastric ulcers with maltoma (12 cases). Clinical and serological signs of autoimmunity correlated strongly with female sex (34, 72% women; and 13, 28% men) and with immunoglobulin alterations. Conclusions. To our knowledge this is the first systematic review of B-lymphoproliferative and autoimmune disorders indicating that pseudolymphoma and malignant lymphomas, including maltomas, may develop in the context of a permanent autoantigenic drive.     

Hysteresis of left ventricular end ejection pressure-dimension relations after acute pressure loading in the intact canine heart

The left ventricular end systolic pressure-volume relation of the isolated canine heart is linear and independent of the loading conditions. The effects of acute pressure loading on the left ventricular end ejection pressure-length relations were studied in the intact canine heart. The lengths of two wall segments of the left ventricle parallel to the minor axis were measured with pairs of miniature piezoelectric crystals. At two levels of filling pressure, with and without control of heart rate, acute increases in left ventricular afterload were produced for six successive beats by occluding the thoracic aorta. After abrupt release of this occlusion, at left ventricular end diastolic pressure less than 10 mmHg, end ejection lengths were longer than before the occlusion for both segments despite the same or lower end ejection pressures. When heart rate was not controlled the mean(SD) difference in end ejection length was 0.46(0.21) mm (n = 100). When heart rate was controlled by atrial pacing after autonomic blockade the difference was 0.37(0.11) mm (n = 80). In contrast, at left ventricular end diastolic pressure greater than 10 mmHg there was no significant difference between end ejection lengths before and after release of the aortic occlusion. Gradual release of the aortic occlusion over 4-5 beats produced clockwise hysteresis of the left ventricular end ejection pressure-length relation when left ventricular end diastolic pressure was less than 10 mmHg. No hysteresis occurred when left ventricular end diastolic pressure was greater than 10 mmHg. Hysteresis of the end systolic pressure-dimension relation was also seen when major and minor axis dimensions of the left ventricular were measured.(ABSTRACT TRUNCATED AT 250 WORDS)     

The interaction of oestrogen receptor status and pathological features with adjuvant treatment in relation to survival in patients with operable breast cancer: a retrospective study of 2660 patients

The oestrogen receptor (ER) status of 2660 patients with primary breast cancer has been related to the effect of different adjuvant systemic therapies on survival. However, as patients in the various treatment groups also had different prognostic features comparison between treatments was difficult. Over 90% of patients receiving tamoxifen (Tam) were postmenopausal compared with <20% of those receiving chemotherapy (CT). The latter had more positive nodes (85% vs 54%) and grade III tumours (54% vs 30%) than the Tam group. The combined CT and Tam group had similar characteristics to the CT alone group. The current reported increase in the proportion of women with ER+ tumours is explained by immunohistochemical analysis of ER and screening programmes. ER status was unrelated to survival in patients with small, low grade, node-negative tumours which was no different from that expected for age-matched women taken from the general population. The value of adjuvant treatment in these patients is therefore questionable. In those given any adjuvant treatment, survival of women with ER+ tumours was prolonged, with the greatest effect being seen in those receiving Tam. Patients with ER- tumours benefited from CT but the addition of Tam to CT improved survival only in those with ER+ tumours. ER status is now established as a major predictive factor for treatment selection in primary disease. Studies of prognostic and predictive markers may be invalidated by use of adjuvant therapy and selection criteria for different treatments. Survival will be influenced by both tumour biology and therapy. This important consideration must be remembered when analysing new markers, particularly in small studies.     

Effects of progressive myocardial ischaemia on systolic function, diastolic dysfunction, and load dependent relaxation.

OBJECTIVE: The aims were to determine (1) the relationship between changes in contractile function (systolic shortening) and the appearance of diastolic dysfunction (postsystolic shortening) during progressive regional left ventricular ischaemia; (2) the effects of increased afterload (acute constriction of the descending thoracic aorta) on ischaemic contractile dysfunction; and (3) the effects of loading during ischaemia on load dependent relaxation. METHODS: Regional myocardial function, using sonomicrometry, was measured in the short and long axes of the apex of the left ventricle of eight open chest anaesthetised dogs (16-20 kg). Progressive apical ischaemia was induced by graded reductions in left anterior descending coronary artery flow (critical constriction, ischaemia 1, ischaemia 2, total coronary occlusion, and postocclusive maximum reactive hyperaemia). Acute afterloading was induced by a snare placed around the descending aorta. RESULTS: Consistent decreases in systolic shortening and increases in postsystolic shortening relative to the total segmental shortening in the short axis of the apical region were seen with worsening ischaemia. Aortic constriction increased the magnitude of apical postsystolic shortening and decreased apical systolic shortening in the short axis during critical constriction, ischaemia 1, and ischaemia 2. Long axis function changed in a qualitatively similar but quantitatively different manner. There was a significant decrease in the load dependency of relaxation with total coronary occlusion. CONCLUSIONS: (1) Changes in systolic and diastolic function occurred concomitantly as mild regional myocardial ischaemia developed and intensified; (2) afterloading significantly worsened regional systolic and diastolic dysfunction during mild ischaemia; and (3) progression of regional ischaemia resulted in loss of load dependent relaxation.