HLA-DPB1*13:01 associates with enhanced, and KIR2DS4*001 with diminished protection from developing severe COVID-19

Extreme polymorphism of HLA and killer-cell immunoglobulin-like receptors (KIR) differentiates immune responses across individuals. Additional to T cell receptor interactions, subsets of HLA class I act as ligands for inhibitory and activating KIR, allowing natural killer (NK) cells to detect and kill infected cells. We investigated the impact of HLA and KIR polymorphism on the severity of COVID-19. High resolution HLA class I and II and KIR genotypes were determined from 403 non-hospitalized and 1575 hospitalized SARS-CoV-2 infected patients from Italy collected in 2020. We observed that possession of the activating KIR2DS4*001 allotype is associated with severe disease, requiring hospitalization (OR = 1.48, 95% CI 1.20-1.85, pc  = 0.017), and this effect is greater in individuals homozygous for KIR2DS4*001 (OR = 3.74, 95% CI 1.75-9.29, pc  = 0.003). We also observed the HLA class II allotype, HLA-DPB1*13:01 protects SARS-CoV-2 infected patients from severe disease (OR = 0.49, 95% CI 0.33-0.74, pc  = 0.019). These association analyses were replicated using logistic regression with sex and age as covariates. Autoantibodies against IFN-α associated with COVID-19 severity were detected in 26% of 156 hospitalized patients tested. HLA-C*08:02 was more frequent in patients with IFN-α autoantibodies than those without, and KIR3DL1*01502 was only present in patients lacking IFN-α antibodies. These findings suggest that KIR and HLA polymorphism is integral in determining the clinical outcome following SARS-CoV-2 infection, by influencing the course both of innate and adaptive immunity.

Complete sequences of six major histocompatibility complex haplotypes, including all the major MHC class II structures

Accurate and comprehensive immunogenetic reference panels are key to the successful implementation of population-scale immunogenomics. The 5Mbp Major Histocompatibility Complex (MHC) is the most polymorphic region of the human genome and associated with multiple immune-mediated diseases, transplant matching and therapy responses. Analysis of MHC genetic variation is severely complicated by complex patterns of sequence variation, linkage disequilibrium and a lack of fully resolved MHC reference haplotypes, increasing the risk of spurious findings on analyzing this medically important region. Integrating Illumina, ultra-long Nanopore, and PacBio HiFi sequencing as well as bespoke bioinformatics, we completed five of the alternative MHC reference haplotypes of the current (GRCh38/hg38) build of the human reference genome and added one other. The six assembled MHC haplotypes encompass the DR1 and DR4 haplotype structures in addition to the previously completed DR2 and DR3, as well as six distinct classes of the structurally variable C4 region. Analysis of the assembled haplotypes showed that MHC class II sequence structures, including repeat element positions, are generally conserved within the DR haplotype supergroups, and that sequence diversity peaks in three regions around HLA-A, HLA-B+C, and the HLA class II genes. Demonstrating the potential for improved short-read analysis, the number of proper read pairs recruited to the MHC was found to be increased by 0.06%-0.49% in a 1000 Genomes Project read remapping experiment with seven diverse samples. Furthermore, the assembled haplotypes can serve as references for the community and provide the basis of a structurally accurate genotyping graph of the complete MHC region.

Polymorphic KIR3DL3 expression modulates tissue-resident and innate-like T cells

Most human killer cell immunoglobulin-like receptors (KIR) are expressed by natural killer (NK) cells and recognize HLA class I molecules as ligands. KIR3DL3 is a conserved but polymorphic inhibitory KIR recognizing a B7 family ligand, HHLA2, and is implicated for immune checkpoint targeting. The expression profile and biological function of KIR3DL3 have been somewhat elusive, so we searched extensively for KIR3DL3 transcripts, revealing highly enriched expression in γδ and CD8+ T cells rather than NK cells. These KIR3DL3-expressing cells are rare in the blood and thymus but more common in the lungs and digestive tract. High-resolution flow cytometry and single-cell transcriptomics showed that peripheral blood KIR3DL3+ T cells have an activated transitional memory phenotype and are hypofunctional. The T cell receptor (TCR) usage is biased toward genes from early rearranged TCR-α variable segments or Vδ1 chains. In addition, we show that TCR-mediated stimulation can be inhibited through KIR3DL3 ligation. Whereas we detected no impact of KIR3DL3 polymorphism on ligand binding, variants in the proximal promoter and at residue 86 can reduce expression. Together, we demonstrate that KIR3DL3 is up-regulated alongside unconventional T cell stimulation and that individuals may vary in their ability to express KIR3DL3. These results have implications for the personalized targeting of KIR3DL3/HHLA2 checkpoint inhibition.

The impact of HLA polymorphism on herpesvirus infection and disease

Human Leukocyte Antigens (HLA) are cell surface molecules, central in coordinating innate and adaptive immune responses, that are targets of strong diversifying natural selection by pathogens. Of these pathogens, human herpesviruses have a uniquely ancient relationship with our species, where coevolution likely has reciprocating impact on HLA and viral genomic diversity. Consistent with this notion, genetic variation at multiple HLA loci is strongly associated with modulating immunity to herpesvirus infection. Here, we synthesize published genetic associations of HLA with herpesvirus infection and disease, both from case/control and genome-wide association studies. We analyze genetic associations across the eight human herpesviruses and identify HLA alleles that are associated with diverse herpesvirus-related phenotypes. We find that whereas most HLA genetic associations are virus- or disease-specific, HLA-A*01 and HLA-A*02 allotypes may be more generally associated with immune susceptibility and control, respectively, across multiple herpesviruses. Connecting genetic association data with functional corroboration, we discuss mechanisms by which diverse HLA and cognate receptor allotypes direct variable immune responses during herpesvirus infection and pathogenesis. Together, this review examines the complexity of HLA-herpesvirus interactions driven by differential T cell and Natural Killer cell immune responses.

Human herpesvirus diversity is altered in HLA class I binding peptides

Herpesviruses are ubiquitous, genetically diverse DNA viruses, with long-term presence in humans associated with infrequent but significant pathology. Human leukocyte antigen (HLA) class I presents intracellularly derived peptide fragments from infected tissue cells to CD8+ T and natural killer cells, thereby directing antiviral immunity. Allotypes of highly polymorphic HLA class I are distinguished by their peptide binding repertoires. Because this HLA class I variation is a major determinant of herpesvirus disease, we examined if sequence diversity of virus proteins reflects evasion of HLA presentation. Using population genomic data from Epstein–Barr virus (EBV), human cytomegalovirus (HCMV), and Varicella–Zoster virus, we tested whether diversity differed between the regions of herpesvirus proteins that can be recognized, or not, by HLA class I. Herpesviruses exhibit lytic and latent infection stages, with the latter better enabling immune evasion. Whereas HLA binding peptides of lytic proteins are conserved, we found that EBV and HCMV proteins expressed during latency have increased peptide sequence diversity. Similarly, latent, but not lytic, herpesvirus proteins have greater population structure in HLA binding than nonbinding peptides. Finally, we found patterns consistent with EBV adaption to the local HLA environment, with less efficient recognition of EBV isolates by high-frequency HLA class I allotypes. Here, the frequency of CD8+ T cell epitopes inversely correlated with the frequency of HLA class I recognition. Previous analyses have shown that pathogen-mediated natural selection maintains exceptional polymorphism in HLA residues that determine peptide recognition. Here, we show that HLA class I peptide recognition impacts diversity of globally widespread pathogens.

Population-genomic analysis identifies a low rate of global adaptive fixation in the proteins of the cyclical parthenogen Daphnia magna

Daphnia are well-established ecological and evolutionary models, and the interaction between D. magna and its microparasites is widely considered a paragon of the host-parasite coevolutionary process. Like other well-studied arthropods such as Drosophila melanogaster and Anopheles gambiae, D. magna is a small, widespread, and abundant species that is therefore expected to display a large long-term population size and high rates of adaptive protein evolution. However, unlike these other species, D. magna is cyclically asexual and lives in a highly structured environment (ponds and lakes) with moderate levels of dispersal, both of which are predicted to impact upon long-term effective population size and adaptive protein evolution. To investigate patterns of adaptive protein fixation, we produced the complete coding genomes of 36 D. magna clones sampled from across the European range (Western Palaearctic), along with draft sequences for the close relatives D. similis and D. lumholtzi, used as outgroups. We analyzed genome-wide patterns of adaptive fixation, with a particular focus on genes that have an a priori expectation of high rates, such as those likely to mediate immune responses, RNA interference against viruses and transposable elements, and those with a strongly male-biased expression pattern. We find that, as expected, D. magna displays high levels of diversity and that this is highly structured among populations. However, compared with Drosophila, we find that D. magna proteins appear to have a high proportion of weakly deleterious variants and do not show evidence of pervasive adaptive fixation across its entire range. This is true of the genome as a whole, and also of putative ‘arms race’ genes that often show elevated levels of adaptive substitution in other species. In addition to the likely impact of extensive, and previously documented, local adaptation, we speculate that these findings may reflect reduced efficacy of selection associated with cyclical asexual reproduction.

Adaptive Admixture of HLA Class I Allotypes Enhanced Genetically Determined Strength of Natural Killer Cells in East Asians

Human natural killer (NK) cells are essential for controlling infection, cancer, and fetal development. NK cell functions are modulated by interactions between polymorphic inhibitory killer cell immunoglobulin-like receptors (KIR) and polymorphic HLA-A, -B, and -C ligands expressed on tissue cells. All HLA-C alleles encode a KIR ligand and contribute to reproduction and immunity. In contrast, only some HLA-A and -B alleles encode KIR ligands and they focus on immunity. By high-resolution analysis of KIR and HLA-A, -B, and -C genes, we show that the Chinese Southern Han (CHS) are significantly enriched for interactions between inhibitory KIR and HLA-A and -B. This enrichment has had substantial input through population admixture with neighboring populations, who contributed HLA class I haplotypes expressing the KIR ligands B*46:01 and B*58:01, which subsequently rose to high frequency by natural selection. Consequently, over 80% of Southern Han HLA haplotypes encode more than one KIR ligand. Complementing the high number of KIR ligands, the CHS KIR locus combines a high frequency of genes expressing potent inhibitory KIR, with a low frequency of those expressing activating KIR. The Southern Han centromeric KIR region encodes strong, conserved, inhibitory HLA-C-specific receptors, and the telomeric region provides a high number and diversity of inhibitory HLA-A and -B-specific receptors. In all these characteristics, the CHS represent other East Asians, whose NK cell repertoires are thus enhanced in quantity, diversity, and effector strength, likely augmenting resistance to endemic viral infections.

Analysis of genomic DNA from medieval plague victims suggests long-term effect of Yersinia pestis on human immunity genes

Pathogens and associated outbreaks of infectious disease exert selective pressure on human populations, and any changes in allele frequencies that result may be especially evident for genes involved in immunity. In this regard, the 1346-1353 Yersinia pestis-caused Black Death pandemic, with continued plague outbreaks spanning several hundred years, is one of the most devastating recorded in human history. To investigate the potential impact of Y. pestis on human immunity genes we extracted DNA from 36 plague victims buried in a mass grave in Ellwangen, Germany in the 16th century. We targeted 488 immune-related genes, including HLA, using a novel in-solution hybridization capture approach. In comparison with 50 modern native inhabitants of Ellwangen, we find differences in allele frequencies for variants of the innate immunity proteins Ficolin-2 and NLRP14 at sites involved in determining specificity. We also observed that HLA-DRB1*13 is more than twice as frequent in the modern population, whereas HLA-B alleles encoding an isoleucine at position 80 (I-80+), HLA C*06:02 and HLA-DPB1 alleles encoding histidine at position 9 are half as frequent in the modern population. Simulations show that natural selection has likely driven these allele frequency changes. Thus, our data suggests that allele frequencies of HLA genes involved in innate and adaptive immunity responsible for extracellular and intracellular responses to pathogenic bacteria, such as Y. pestis, could have been affected by the historical epidemics that occurred in Europe.

Human herpesvirus diversity is altered in predicted HLA class I binding peptides

Human Leukocyte Antigen (HLA) Class I molecules present intracellularly derived peptide fragments for discrimination of self from non-self, thereby alerting the adaptive immune response to infecting pathogens. Among these pathogens are herpesviruses, including Epstein-Barr virus (EBV), which are large DNA viruses that have coevolved with humans. Previous analyses suggest that natural selection pressures imposed by HLA recognition may affect herpesvirus genetic diversity, especially for proteins involved in the establishment of latency. Because HLA allele frequencies are highly differentiated across human populations, we tested the hypothesis that herpesvirus latency genes have also become differentiated across human populations through adaptation to the local HLA environment. We predicted the protein regions most likely to be recognized by HLA in EBV, Human cytomegalovirus (HCMV), and Varicella-zoster virus (VZV) strains from >15 representative human populations. We compared sequence diversity and population differentiation in HLA-binding and non-binding regions of lytic and latent herpesvirus proteins. We observed increased population differentiation in herpesvirus latent proteins, specifically in regions targeted by HLA. Whereas HLA recognizes conserved peptides in most viral proteins, this pattern was reversed in HLA binding sites of EBV and HCMV proteins expressed in latency. We also predicted fewer HLA-binding latent EBV peptides from higher frequency HLA alleles, consistent with EBV adapting away from HLA recognition. Together, these results suggest that EBV and HCMV diversity is altered in regions recognized by HLA, perhaps due to population-specific natural selection by local HLA alleles.

The combinatorial diversity of KIR and HLA class I allotypes in Peninsular Malaysia

Killer cell immunoglobulin-like receptors (KIRs) interact with polymorphic human leucocyte antigen (HLA) class I molecules, modulating natural killer (NK) cell functions and affecting both the susceptibility and outcome of immune-mediated diseases. The KIR locus is highly diverse in gene content, copy number and allelic polymorphism within individuals and across geographical populations. To analyse currently under-represented Asian and Pacific populations, we investigated the combinatorial diversity of KIR and HLA class I in 92 unrelated Malay and 75 Malaysian Chinese individuals from the Malay Peninsula. We identified substantial allelic and structural diversity of the KIR locus in both populations and characterized novel variations at each analysis level. The Malay population is more diverse than Malay Chinese, likely representing a unique history including admixture with immigrating populations spanning several thousand years. Characterizing the Malay population are KIR haplotypes with large structural variants present in 10% individuals, and KIR and HLA alleles previously identified in Austronesian populations. Despite the differences in ancestries, the proportion of HLA allotypes that serve as KIR ligands is similar in each population. The exception is a significantly reduced frequency of interactions of KIR2DL1 with C2+ HLA-C in the Malaysian Chinese group, caused by the low frequency of C2+ HLA. One likely implication is a greater protection from preeclampsia, a pregnancy disorder associated with KIR2DL1, which shows higher incidence in the Malay than in the Malaysian Chinese. This first complete, high-resolution, characterization of combinatorial diversity of KIR and HLA in Malaysians will form a valuable reference for future clinical and population studies.

Isolation of a natural DNA virus of Drosophila melanogaster, and characterisation of host resistance and immune responses

Drosophila melanogaster has played a key role in our understanding of invertebrate immunity. However, both functional and evolutionary studies of host-virus interaction in Drosophila have been limited by a dearth of native virus isolates. In particular, despite a long history of virus research, DNA viruses of D. melanogaster have only recently been described, and none have been available for experimental study. Here we report the isolation and comprehensive characterisation of Kallithea virus, a large double-stranded DNA virus, and the first DNA virus to have been reported from wild populations of D. melanogaster. We find that Kallithea virus infection is costly for adult flies, reaching high titres in both sexes and disproportionately reducing survival in males, and movement and late fecundity in females. Using the Drosophila Genetic Reference Panel, we quantify host genetic variance for virus-induced mortality and viral titre and identify candidate host genes that may underlie this variation, including Cdc42-interacting protein 4. Using full transcriptome sequencing of infected males and females, we examine the transcriptional response of flies to Kallithea virus infection and describe differential regulation of virus-responsive genes. This work establishes Kallithea virus as a new tractable model to study the natural interaction between D. melanogaster and DNA viruses, and we hope it will serve as a basis for future studies of immune responses to DNA viruses in insects.

Natural Variation in Resistance to Virus Infection in Dipteran Insects

The power and ease of Drosophila genetics and the medical relevance of mosquito-transmitted viruses have made dipterans important model organisms in antiviral immunology. Studies of virus-host interactions at the molecular and population levels have illuminated determinants of resistance to virus infection. Here, we review the sources and nature of variation in antiviral immunity and virus susceptibility in model dipteran insects, specifically the fruit fly Drosophila melanogaster and vector mosquitoes of the genera Aedes and Culex. We first discuss antiviral immune mechanisms and describe the virus-specificity of these responses. In the following sections, we review genetic and microbiota-dependent variation in antiviral immunity. In the final sections, we explore less well-studied sources of variation, including abiotic factors, sexual dimorphism, infection history, and endogenous viral elements. We borrow from work on other pathogen types and non-dipteran species when it parallels or complements studies in dipterans. Understanding natural variation in virus-host interactions may lead to the identification of novel restriction factors and immune mechanisms and shed light on the molecular determinants of vector competence.

Systematic analysis reveals tumor-enhancing and -suppressing microRNAs in Drosophila epithelial tumors

Despite their emergence as an important class of noncoding RNAs involved in cancer cell transformation, invasion, and migration, the precise role of microRNAs (miRNAs) in tumorigenesis remains elusive. To gain insights into how miRNAs contribute to primary tumor formation, we conducted an RNA sequencing (RNA-Seq) analysis of Drosophila wing disc epithelial tumors induced by knockdown of a neoplastic tumor-suppressor gene (nTSG) lethal giant larvae (lgl), combined with overexpression of an active form of oncogene Ras (Ras^V12 ), and identified 51 mature miRNAs that changed significantly in tumorous discs. Followed by in vivo tumor enhancer and suppressor screens in sensitized genetic backgrounds, we identified 10 tumor-enhancing (TE) miRNAs and 11 tumor-suppressing (TS) miRNAs that contributed to the nTSG defect-induced tumorigenesis. Among these, four TE and three TS miRNAs have human homologs. From this study, we also identified 29 miRNAs that individually had no obvious role in enhancing or alleviating tumorigenesis despite their changed expression levels in nTSG tumors. This systematic analysis, which includes both RNA-Seq and in vivo functional studies, helps to categorize miRNAs into different groups based on their expression profile and functional relevance in epithelial tumorigenesis, whereas the evolutionarily conserved TE and TS miRNAs provide potential therapeutic targets for epithelial tumor treatment.

RNA helicase Belle/DDX3 regulates transgene expression in Drosophila

Belle (Bel), the Drosophila homolog of the yeast DEAD-box RNA helicase DED1 and human DDX3, has been shown to be required for oogenesis and female fertility. Here we report a novel role of Bel in regulating the expression of transgenes. Abrogation of Bel by mutations or RNAi induces silencing of a variety of P-element-derived transgenes. This silencing effect depends on downregulation of their RNA levels. Our genetic studies have revealed that the RNA helicase Spindle-E (Spn-E), a nuage RNA helicase that plays a crucial role in regulating RNA processing and PIWI-interacting RNA (piRNA) biogenesis in germline cells, is required for loss-of-bel-induced transgene silencing. Conversely, Bel abrogation alleviates the nuage-protein mislocalization phenotype in spn-E mutants, suggesting a competitive relationship between these two RNA helicases. Additionally, disruption of the chromatin remodeling factor Mod(mdg4) or the microRNA biogenesis enzyme Dicer-1 (Dcr-1) also alleviates the transgene-silencing phenotypes in bel mutants, suggesting the involvement of chromatin remodeling and microRNA biogenesis in loss-of-bel-induced transgene silencing. Finally we show that genetic inhibition of Bel function leads to de novo generation of piRNAs from the transgene region inserted in the genome, suggesting a potential piRNA-dependent mechanism that may mediate transgene silencing as Bel function is inhibited.

PCR-single-stranded confirmational polymorphism analysis for non-culture-based subtyping of meningococcal strains in clinical specimens

Subspecific typing of clinical meningococcal strains is important in the investigation of outbreaks and for disease surveillance. Serogrouping, typing, and subtyping of strains currently require isolation of a meningococcus from one or more clinical specimens. However, the increasing widespread practice of preadmission administration of parenteral antibiotics has resulted in a decrease in the frequency of positive cultures obtained from blood and cerebrospinal fluid. Confirmation of meningococcal disease can be obtained by meningococcus-specific PCR from both cerebrospinal fluid (H. Ni et al., Lancet 340:1432-1434, 1992) and peripheral blood (J. Newcombe et al., J. Clin. Microbiol. 34:1637-1640, 1996) specimens. However, current PCR protocols do not yield epidemiologically useful typing information. We report here the use of PCR-single-stranded confirmational polymorphism (PCR-SSCP) analysis to amplify and type meningococcal DNA present in clinical specimens. PCR-SSCP analysis with the VR1 region of the Neisseria meningitidis porA gene as the target produced unique banding patterns for each serosubtype. Direct PCR-SSCP of clinical specimens can therefore provide typing data that can be used to investigate the epidemiology of clusters of cases and outbreaks and for disease surveillance in situations in which culture of patient specimens proves negative.

PCR of peripheral blood for diagnosis of meningococcal disease

Meningococcal disease is normally suspected on clinical grounds and is confirmed by isolation of Neisseria meningitidis bacteria from blood or cerebrospinal fluid or, more recently, by serology or PCR of cerebrospinal fluid. Achieving confirmation of a clinical diagnosis of meningococcal disease has become more difficult in the last few years. The pre-hospitalization administration of parenteral benzylpenicillin normally renders blood cultures sterile, and lumbar puncture is undertaken less frequently, especially in young children. We evaluated PCR for the detection of meningococcal DNA in 80 blood samples taken from patients with known or suspected meningococcal disease or from patients with other diagnoses (negative controls). Both the sensitivity and the specificity of the test were 100% for patients with confirmed cases of meningococcal disease when the blood buffy coat was used (83 to 100% sensitivity and 87 to 100% specificity with 95% confidence limits). Positive PCR results could be obtained from both blood buffy coat and serum samples. Sensitivity was unaffected by prior antibiotic treatment. PCR is a rapid, sensitive test that may be used to confirm a diagnosis of meningococcal disease by using peripheral blood samples. Introduction of this test into clinical laboratories may in some cases obviate the need for lumbar puncture to be performed on patients with suspected meningococcal disease. Our results demonstrate that a substantial number of cases of meningococcal disease are not confirmed by conventional techniques and remain undiagnosed. If the PCR test described here was widely applied, the number of cases of meningococcal disease ascertained might rise by as much as 60% greater than that recognized at present. It is likely that we are in a prevaccination era for meningococcal disease. Better case ascertainment is urgently required to assess the need for vaccines, to determine their costs and benefits, and to monitor their efficacies.

An international perspective on the cholesterol debate

For the past 5 years there has been an intensive debate and a number of conflicting guidelines suggesting what general practitioners (GPs) should do to screen and manage hyperlipidaemia. At a WONCA seminar in Vancouver in 1992, policies and guidelines from Canada, the UK, The Netherlands, New Zealand, Hong Kong and the USA were reviewed. It was concluded that cholesterol policy and guidelines tend to be influenced more by political and economic factors than by evidence of health benefit. International guidelines for cholesterol screening and management would be of minimal value, as GPs would have to interpret the epidemiological evidence of benefit from lipid screening and lipid lowering strategy in the context of each patient to arrive at optimum management.

Dissemination of guidelines on cholesterol. Effect on patterns of practice of general practitioners and family physicians in Ontario. Ontario Task Force on the Use and Provision of Medical Services

A telephone survey of a random sample of Ontario family physicians was conducted 6 to 8 months after disseminating evidence-based guidelines for screening and managing asymptomatic hypercholesterolemia. Seventy-eight percent of respondents stated they followed these guidelines. However, specific questions revealed as few as 5% of respondents actually followed the guidelines.

Polymerase chain reaction for diagnosis of meningococcal meningitis

Meningococcal disease is normally suspected on clinical grounds but confirmed by isolation of Neisseria meningitidis from blood or cerebrospinal fluid (CSF), or by detection of gram-negative diplococci in CSF. After parenteral antibiotics are started the isolation rate of meningococci from blood cultures drops from 50% to less than 5% and the chances of CSF being positive by culture or microscopy are also reduced. We used the polymerase chain reaction (PCR) in a blinded study to detect meningococcal DNA in 54 CSF samples from patients with meningococcal disease or from controls. The PCR primers were specific for the meningococcal insertion sequence IS1106. The sensitivity and specificity of this PCR for diagnosis of meningococcal meningitis were both 91%. Sensitivity was not affected by prior antibiotic treatment. The IS1106 PCR is a rapid and sensitive test for confirmation of the diagnosis of meningococcal meningitis.

Introducing a new drug into your practice

Many consultations in family practice end with a prescription for medication. The average market life of a new drug is only five years. Keeping up to date on therapeutic advances is an essential CME activity. Family physicians usually hear about new drugs from the pharmaceutical representatives. Before one changes well-established habits of practice it is necessary to evaluate non-commercial sources of data. A good understanding of the implications of clinical trials is required. The availability and accuracy of other sources of information are discussed.

Rehabilitation after myocardial infarction

The family physician plays an important role in rehabilitating a patient following a heart attack. Knowing the factors which influence the prognosis allows the therapeutic regimen to be individualized. Careful medical assessment is required throughout the program, and familiarity with medications to reduce the risk of complications is essential. The patient and his family should be educated to assist the patient to enjoy a lifestyle and attitude which should be healthier than it was before the acute cardiac event.

The Physician's Approach to Hypertension in the Office

The family physician must take a comprehensive approach to managing hypertension in the office, to prevent the cardiovascular complications of atherosclerosis. Many risk factors interact to produce the vascular damage which culminates in stroke, myocardial infarction and heart failure. With each patient all the risk factors must be assessed and a specific treatment plan developed. Reduction of elevated blood pressure alone has no consistent effect on the incidence of heart attacks. Pharmacological therapy is usually required for patients with persistently elevated diastolic pressure; this should not exclude the concurrent use of non-pharmacological interventions. As the side effects of hypotensive drugs are common and non-specific, step-down therapy should be considered in those patients whose blood pressure has been controlled for one year.

Lifestyle assessment: just asking makes a difference

A 10 minute assessment of 180 family practice patients showed that 11% indicated a problem with drinking alcohol, 20% with cigarette smoking, 36% with consumption of coffee or tea, and 3% with non-medical drug use, while 11% wanted to discuss their use of medications. Moreover, being asked questions resulted in a twofold or threefold increase in the patients' intentions of discussing such a problem with their doctor. Although there was good overall agreement in recognising a problem between the patient and doctor, in roughly 40% of instances where the patient indicated a problem the doctor was unaware of it. These patients tended to be young, well educated, and employed in professional occupations, and were on their first visit to the doctor. Such brief assessments of lifestyle should be routinely conducted in family practice for both case finding and prevention.

Lifestyle assessment: applying microcomputers in family practice

A randomised trial of assessment by computer was conducted with 180 patients in a family practice clinic. Histories of alcohol, tobacco, and drug use were obtained by computer (n = 60), interview (n = 60), or self completed questionnaire (n = 60). The results of previous research suggest that some patients may provide more accurate information about "sensitive" problems to a computer. No significant differences, however, in levels of consumption or problems were reported for the three methods of assessment. Patients gave differential ratings about the method of assessment, with the computer rated as more interesting but also more mechanical, cold, and impersonal. Although the interview was initially preferred by most, patients who completed the assessment by computer showed a significant increase (13% to 43%) in their preference for the computer after the assessment. The results of our study indicate that patients' acceptance of computers in family practice may be favourably influenced by direct experience with a microcomputer.

The evaluation of clinical competence

During a workshop on the evaluation of clinical competence, the participants identified the process skills that comprise clinical competence and examined the techniques available for evaluating these skills. No single technique allows satisfactory evaluation of all the process skills; the most commonly used methods (chart review and case presentation) evaluate few process skills. An adequate performance profile in all the process skills requires a combination of evaluation techniques. Medical evaluators should strive to define clinical competence in measurable terms, based on the clinical skills to be mastered and the spectrum of clinical situations to be managed.

Ventricular preexcitation syndrome. Accessory left atrioventricular connection and rhabdomyomatous myocardial fibers

A necropsy study of the heart of a 16-year-old girl with ventricular preexcitation syndrome and supraventricular tachycardia showed an accessory left atrioventricular connection partially within the mitral valve. Both the accessory pathway and the ventricular musculature showed multiple foci of cardiac muscle fibers with rhabdomyomatous features having the characteristic appearance of rhabdomyomatosis. The case is discussed in the context of a literature review of necropsy findings in cases of ventricular preexcitation.

The effect of coronary vasodilatation (dipyridamole-induced) on the myocardial distribution of tritiated water

The uptake of tritiated water in the left ventricle has been studied during constantly increasing concentrations of tritium in two groups of normal dogs, one of which received dipyridamole intravenously while the other acted as control. Dipyridamole administration was associated with a 1.6 times greater coronary flow and an appropriate reduction in arterial coronary sinus oxygen difference. As judged by the concentrations of indicator in different myocardial samples the perfusion of the myocardium of the normal dog is relatively homogeneous. No differences were detected between the inner and outer half of the ventricular wall or between the apical region and the free wall of the left ventricle. Comparison of myocardial and coronary sinus concentrations of tritium indicated that the increased coronary flow following dipyridamole was the result of an increase in the effective capillary flow rather than a shunting through diffusion-limited pathways, such as would occur in functional or anatomical arterio–venous shunts.

Influence of respiration on venous return in pulmonary emphysema

The influence of respiration on the flow of blood from the abdominal vena cava into the thorax was studied in 15 patients with pulmonary emphysema and in 10 control subjects without thoracic disease or heart failure. In control subjects, during quiet breathing blood flowed into the thorax throughout the respiratory cycle at a rate which was greatest during inspiration. Simultaneously the transmural pressure of the abdominal vena cava fell and transmural right atrial pressure increased. The same pattern of flow was observed in nine of the patients with emphysema. In the other six patients, however, flow was greatly reduced or completely arrested during inspiration, with simultaneous increase in transmural caval pressure and reduction in transmural atrial pressure. This inspiratory obstruction at the thoracic inlet was associated with gross hyperinflation of the lungs and a low diaphragmatic position. It probably was not the result of the high negative and positive intrathoracic pressures that develop during inspiration and expiration, respectively, in such subjects.

It is possible that this phenomenon may account for the peripheral edema that occurs in patients who have emphysema without associated pulmonary hypertension or cardiomegaly.