Heterogeneity of myocardial perfusion provides the physiological basis of perfusable tissue index.

UNLABELLED: Assessment of viable from nonviable myocardium is critical for the care of patients being considered for revascularization procedures. Recently, the perfusable tissue index (PTI) has been proposed as an index of myocardial viability. METHODS: Computer simulations were performed for homogeneously and heterogeneously perfused tissue over a wide range of flows (0.04-6.4 ml/g/min) using both bolus and infusion inputs. RESULTS: PTI estimated from simulated homogeneously perfused tissue did reflect the amount of tissue being perfused independent of absolute level of flow, type of input or model configuration, whereas PTI obtained from simulated heterogeneously perfused tissue was consistently lower than the simulated "true" PTI and varied with flow, type of input function and model configuration. Flow estimated with 15O-water was not significantly different from that measured with radio labeled microspheres. CONCLUSION: Oxygen-15-water can diffuse into both acutely and chronically ischemic myocardium irrespective of its functional status. The results suggest that PTI is most likely an index of the heterogeneity of myocardial flow rather than an index of the amount of tissue being perfused. Its utility for delineating myocardial viability is thus related to the amount of tissue perfused that has low absolute levels of perfusion or high degrees of flow heterogeneity.

Blunt cardiac trauma: atrioventricular valve disruption and ventricular septal defect.

Nonpenetrating cardiac trauma resulting in cardiac chamber or valvar rupture is uncommon, requiring a high degree of suspicion for diagnosis. A case involving avulsion of the tricuspid and mitral papillary muscles with resultant interventricular septal rupture is reported. This case illustrates the importance of transesophageal echocardiography in the rapid diagnosis of blunt cardiac trauma. Surgical treatment of this condition is also discussed.

Mermithid parasitism of Simulium damnosum s.l. and the transmission of human onchocerciasis.

Dissection data from a Simulium damnosum s.l. population in northern Ghana, heavily parasitized by the mermithid Isomermis lairdi, are presented. A simple calculation gives reason to suppose that this parasitism may significantly reduce the transmission of onchocerciasis at certain seasons.

Identification of two West African black flies (Diptera: Simuliidae) of the Simulium damnosum species complex by analysis of cuticular paraffins.

Simulium damnosum is known to be a sibling species complex with at least 24 cytotaxonomically distinct forms in Africa. Of these, six occur in the area of West Africa covered by the World Health Organization Onchocerciasis Control Programme. They are all vectors of Onchocerca volvulus, and several are capable of migrating great distances. We report here a comparatively simple chemical method of species identification using individual adult females of pooled samples that have been collected and stored dry in glass vials. Females of two species, S. sirbanum and S. squamosum, were identified by extraction and analysis of cuticular components using gas chromatography. Statistically significant differences were seen between these two species for each of five sets of consistently appearing peaks that were quantitated and compared. The technique has considerable potential for use in the field since extracts or specimens may be stored indefinitely at ambient temperature before analysis.

The impact of burn injury: a preliminary investigation.

Thirty-eight individuals who had been previously hospitalized for burn injuries were interviewed about the problems that they had experienced as a result of their injuries, their rehabilitation goals, and factors that they believed had influenced either the rate or extent of their recovery. The problems that were most frequently mentioned by participants were compared with problem areas that are covered by the Burn-Specific Health scale, which is a standardized measure designed to assess the impact of burn injury. Our findings suggest that although many problem areas are well covered by the Burn-Specific Health scale, other areas are covered less well. Thus more work is needed to refine the scale to capture more fully the wide variety of problems that are experienced by survivors of burn injuries. In general, patients' rehabilitation goals reflected the types of problems they experienced. Support from health care providers was the most frequently mentioned facilitator to recovery, which emphasizes the importance of the patient-provider relationship.

Date and acquaintance rape. Development and validation of a set of scales.

PIP: Increasing recognition of the prevalence of date/acquaintance rape (DAR) in the US, especially among college women, has led to an understanding that the techniques needed to fend off attacks from friends and acquaintances differ from those used to prevent rape by strangers. This study developed and tested the reliability and validity of the following DAR constructs: perceived vulnerability (underestimation of vulnerability discourages adequate self-protection), self-efficacy, relational priority (neglecting self-interest to save a relationship), rape myth acceptance (subscribing to myths about rape allows women to avoid facing their own vulnerability), and commitment to self-defense. These constructs were also correlated with scales measuring masculinity, self-esteem, and degree of belief in a "just world." Data were gathered to test these constructs via a questionnaire administered to 800 female undergraduate dormitory residents (47% response rate). Analysis of the data allowed refinement of 50 items into 25 items that constitute reliable scales of perceived vulnerability, self-efficacy, and self-determination and a marginally reliable scale of victim-blaming (rape myth). Support was found for 5/6 predicted correlates between DAR scales and 3/5 hypothesized correlations between DAR scales and convergent/discrimination validity scales. Research into this rape prevention tool will continue.^ieng

Elimination of the Djodji form of the blackfly Simulium sanctipauli sensu stricto as a result of larviciding by the WHO Onchocerciasis Control Programme in West Africa.

Cytotaxonomic identifications of larvae of members of the Simulium damnosum Theobald (Diptera: Simuliidae) complex collected in forest zones of southeast Ghana and southwest Togo between 1977 and 1996 showed that the Djodji form of Simulium sanctipauli Vajime & Dunbar, a vector of onchocerciasis, was eliminated in 1988 by larvicide operations conducted by the World Health Organization (WHO) Onchocerciasis Control Programme (OCP) in West Africa. No members of the form were identified amongst 997 larvae collected up to 8 years after systematic control operations began in February 1988. The results are discussed in relation to estimates of the numbers of samples required to certify elimination and the possibility that other members of the S. damnosum complex were also eliminated by the OCP.

Review of vector control prior to the OCP.

It is a little over 60 years since Blacklock, in an elegant study, demonstrated that in Sierra Leone human onchocerciasis was transmitted by a Simulium fly. Amazingly within 6 years of Blacklock's discovery an attempt was made, mainly using environmental management, to control Simulium in the Chiapas focus of Mexico, though this was not successful. Later Buckley was successful in eradicating Simulium neavei from the small Riana focus in Kenya by clearing riverine forest. However, it was not until DDT became widely available that Simulium control entered its heroic phase with campaigns in Kenya, Uganda and Zaire, some of which were highly successful. This led to an interest in controlling the vector in West Africa. The very different pattern of disease with very large foci virtually contiguous across tens of thousands of square kilometers suggested a difficult proposition and early attempts were not very successful. There is much of interest in the East and Central African schemes and in the West African forerunners of the OCP. In this talk an attempt will be made to capture something of the flavour of these pioneering efforts, to give credit to the men involved, and to highlight the successes against both the S. neavei and S. damnosum complex, and the advances which contributed to the successful planning of the OCP.

Training for day-case dental anaesthesia. Oxygen saturation during general anaesthesia administered by dental undergraduates.

Sixty-seven patients undergoing general anaesthesia for exodontia as outpatients were studied in order to measure the levels of oxygen saturation. Both the anaesthesia and extractions were performed by fourth year dental undergraduates working under direct supervision. Falls in oxygen saturation in excess of 5% were found in three groups of patients receiving 20%, 25%, and 30% oxygen in the inspired mixture.

Sticky trap studies on Simulium damnosum s.l. in northern Ghana.

The results of sticky trapping S. damnosum s.l. at several sites in northern Ghana are given. Yields were always very much lower than those which could be obtained by human bait catches, and caught flies tended to disappear from traps which were not emptied at least daily. Thus the technique offered little promise as a means of monitoring population fluctuations. Nevertheless some valuable information was obtained. Colour choice studies showed that hunting flies were attracted to dark blue substrates. In all situations the most shaded surfaces of the traps were preferred by alighting flies. The presence of S. damnosum in the canopies of trees was demonstrated for the first time. Flies were caught at heights above 6 m at three sites, the maximum height being 9.2 m, the height of the topmost trap. Among flies caught in the canopy of trees were nulliparous, parous and gravid females as well as males. Only in one catch, at relatively low levels in riverine trees, were blood engorged flies a noteworthy proportion of the catch.

Light trap studies on Simulium damnosum s.l. in Northern Ghana.

The results of light trapping S. damnosum s.l. in northern Ghana during both the wet and dry season are given. It is considered that some flight activity takes place throughtout the night at both seasons. Flies in different physiological states behave differently and gravid females and newly emerged flies appear to be strongly phototactic. There is little evidence to suggest that light trapping is likely to be useful for the capture of blood engorged flies and for the routine monitoring of S. damnosum populations. Further work on the use of light traps in Stimulium studies is required.