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Biomedical subjects

S R Wilson

Publications and source records attributed to S R Wilson.

At least 19 recordsLinked to original sources
PubMed1992

Predicting AIDS deaths and prevalence in Australia.

OBJECTIVE: To describe a method for predicting deaths from, and the prevalence of, the acquired immunodeficiency syndrome (AIDS) in Australia and to obtain ranges of projections for the next five years based on data observed to 30 September 1989 and reported by January 1990. The projections are important components of planning for future health-care needs. PATIENTS: All patients with AIDS in Australia who were known to the National Centre in HIV Epidemiology and Clinical Research. The data used in the analysis were date of diagnosis of AIDS, date of death if the patient had died, and State or Territory of diagnosis. RESULTS: For Australia as a whole, the doubling time of AIDS incidence changed from 0.83 years before mid 1987 to 4.34 years after that time. Five hundred and seventy patients were diagnosed with AIDS to 30 June 1987 of whom 487 had died by 30 September 1989 and the estimated mean survival time was 1.36 years. Of 1037 patients diagnosed with AIDS after June 1987, 352 had died and the estimated mean survival time was 2.42 years. Combining the estimated survival distribution with the projected new cases of AIDS, we forecast that there will be between 530 and 680 deaths from AIDS in Australia in the year mid 1991 to mid 1992. Estimated cumulative deaths to mid 1994 range from 3390 to 4250. We predict that there will be between 1370 and 1850 people living with AIDS during the year ending mid 1992, and that this number will increase to between 1760 and 2830 for the year ending mid 1994. We also predict that the prevalence of AIDS in New South Wales will lie between 820 and 1620 for the year ending mid 1994, and that the prevalence in Victoria will lie between 270 and 740 in the same year. CONCLUSIONS: Any value in the range of predictions for AIDS incidence we give is equally likely and there is good agreement with the data now observed from mid 1989 to mid 1990. The dramatic increase in the doubling time is the result of a number of factors predicted by epidemic theory and the availability of treatment, zidovudine in particular. Our estimates of deaths and prevalence have been influenced by the quality of the available death data. The observed number of deaths in the year mid 1989 to mid 1990 has exceeded the number forecast for that year. Substantial improvements in survival were associated with the introduction of zidovudine into clinical practice in mid 1987 but the death rate has risen rapidly again in the very recent past, possibly due to patients becoming increasingly refractory to treatment with zidovudine (before or after a diagnosis of AIDS). Our approach to forecasting can be adjusted to accommodate a transient effect of treatment as further data accumulate.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Structures of methyl 7-phenyldibenz[a,j]anthracene-14-carboxylate and methyl 7-phenylbenzo[1,2-h:5,4-h']diquinoline-14-carboxylate: twisted aromatic spacers containing bay-region esters.

C30H20O2, (1), Mr = 412.49, triclinic, P1 (Ci1), a = 11.301 (7), b = 12.069 (3), c = 9.777 (2) A, alpha = 96.12 (2), beta = 111.59 (4), gamma = 114.68 (3) degrees, V = 1072 (2) A3, Z = 2, Dx = 1.278 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.73 cm-1, F(000) = 432, T = 299 K, final R = 0.065 for 1231 observed reflections. C28H18N2O2, (2), Mr = 414.46, monoclinic, I2/a (C2h6), a = 20.039 (10), b = 11.762 (8), c = 19.850 (5) A, beta = 117.61 (3) degrees, V = 4146 (8) A3, Z = 8, Dx = 1.328 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.79 cm-1, F(000) = 1728, T = 298 K, final R = 0.048 for 1924 observed reflections. Aromatic system (1) is highly twisted (43 degrees from end to end) in a helical sense. Half of aromatic system (2) is nearly planar with the ester C atom, whereas the other half is twisted by ca 27 degrees for planarity.

Benz(a)Anthracenes↗
PubMed1992

Non-Hodgkin lymphoma in the porta hepatis after orthotopic liver transplantation: sonographic findings.

The sonographic appearances of primary non-Hodgkin lymphoma developing in the porta hepatis in three patients soon after hepatic transplantation were reviewed. The lymphomas appeared as large hypoechoic masses encasing vital portal structures--the hepatic artery and the common bile duct--in all three cases and displacing the portal vein in two. The liver was only locally involved. All patients presented with jaundice soon after transplantation (average interval, 6.3 months). Rapid tumor progression caused hepatic infarction, necessitating retransplantation in two patients. The third patient died shortly after diagnosis. The authors believe this complication will be seen increasingly as liver transplantation becomes more common. Non-Hodgkin lymphoma should be considered when an obstructing mass is found in the porta hepatis, even when the time interval since transplantation is short.

Common Bile Duct↗
PubMed1992

Gastrointestinal sonography.

The contribution of routine gray-scale sonography in the gastrointestinal tract has been augmented by the addition of duplex Doppler and, more recently, color Doppler imaging. Many recent reports focus on the deep abdominal applications of these modalities. Although duplex tracing remains the basis of most diagnoses, the use of color Doppler imaging has facilitated the performance of these examinations. Endosonography performed with high-resolution transducers in the lumen of the gut is another exciting and expanding area. Staging of gastrointestinal tumors is the major application of this modality. Future sonographic developments include the promise of contrast agents.

Digestive System Diseases↗
PubMed1992

Sensitivity analyses for the backcalculation method of AIDS projections.

In Australia, AIDS is a notifiable disease and the data have been of a relatively high quality. In this article, the cases among Australian residents diagnosed by mid-1989 and reported by January 1990 are used to evaluate the sensitivity of estimates of numbers infected with the human immunodeficiency virus (HIV) and of projections of numbers of new AIDS diagnoses to major uncertainties in the method of backcalculation. We find that the estimates and long-term projections are sensitive to all uncertainties, including the incubation period distribution, the new infection intensity distribution, and the level of data aggregation chosen for analysis. Further, we find the projection that is least sensitive to all uncertainties, namely AIDS diagnoses for the next year (mid-1989 to mid-1990), falls in a relatively narrow range that encompasses the number that had been reported by April 1991.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The evolution and impact of the national AHEC program over two decades.

The national Area Health Education Center (AHEC) program began in 1972 with the purpose of addressing problems of the shortage of physicians and the maldistribution of health professionals. The 40 projects of the program have involved 37 states, 55 medical schools, numerous other health professions schools, and 117 local community AHECs. This 19-month study (1988-1990) was undertaken to systematically assess and clarify the organization, functions, activities, and effects of the national AHEC program over two decades. Data sources were mainly 263 interviews of persons representing the full spectrum of those associated with and participating in AHECs. The findings describe a national network of school and community partnerships that were engaged in planning and implementing educational activities and were responsive to changing needs of health care. The individual AHECs differ in structure and activities as a function of the era in which each began, legislative requirements, and the specific community's needs for health professionals. As organizations, AHECs have unique functions that appear to have benefited the target communities or regions, participating schools, students, and medical school residents. Viability of AHECs in the future will depend on their ability to maintain a focus on health professions education in spite of state or community pressure to provide direct services--both clinical services and public education. At the same time, success will depend on the AHECs' capacity to respond effectively to changing needs of the community and the health care delivery system.

Area Health Education Centers↗
PubMed1991

Pseudomembranous colitis: sonographic features.

The sonographic features of pseudomembranous colitis (PMC) are described in 13 patients and correlated with clinical, radiologic, and pathologic findings. At sonography, the wall of the entire colon was moderately to markedly thickened in all patients. The enlarged colon wall was most commonly shown as a wide band of heterogeneous medium echogenicity surrounded by a narrow hypoechoic layer. Pathologic correlations proved that the wide inner stratum represented severely edematous submucosa and mucosa, while the outer layer depicted the muscularis propria. Almost complete effacement of the lumen of the colon occurred secondary to the mural edema in 69% of the cases. The dearth of intraluminal gas combined with thickening of the colon wall and ascites facilitated excellent sonographic evaluation. The diagnosis of PMC is strongly suggested by the presence of these sonographic features in a patient with watery diarrhea and a history of antibiotic therapy.

Adult↗
PubMed1991

Cecal diverticulitis mimicking appendicitis on ultrasonography.

The authors describe a case of acute cecal diverticulitis in which the ultrasonographic features, as well as the clinical features, mimicked those of acute appendicitis. Though rare, acute cecal diverticulitis is an important differential diagnosis when ultrasonographic features suggest acute appendicitis, because the condition can be managed initially without surgery.

Adult↗
PubMed1990

Predicting the course of AIDS in Australia.

There have been urgent demands for knowledge about the epidemic of the acquired immunodeficiency syndrome (AIDS) in Australia. Accurate predictions are important for efficient allocation and planning of limited health-care resources. Ideal data for this purpose would be reliable knowledge of the past and present incidence of human immunodeficiency virus (HIV) infection. However, since the incidence of the infection is unknown predictions can only be based on historical data of the incidence of AIDS. In this article, we show the limitations of such predictions by examining a broad range of mathematical models that successfully track the observed data (1187 cases diagnosed to December 31, 1988). In addition, we describe a simple method for prediction in subgroups where the numbers of cases observed so far are small. Four models representing different forms of departure from the simple exponential model provide the best fits to the Australian AIDS data. Regional variability and a possible effect resulting from the introduction of zidovudine were incorporated into the models. Significant regional variability in the course of the epidemic was observed between New South Wales, Victoria and the rest of the country. For Australia as a whole, the doubling time changed from less than one year before mid 1987 to more than two years after this time. Model fits were improved by fitting the models to just the four years of data from 1985. The models give comparable predictions for the first year (1989) of around 600 new cases. However, by 1993 the predictions vary considerably, ranging from 500 to 2300 new cases. It is predicted that between 3100 and 6700 cases are likely to be diagnosed in Australia between 1989 and 1993. The results from the subgroup prediction demonstrate that when the observed number of cases is small, then the range of predictions for a future time interval is very wide. For reliable long-term predictions that are necessary for public health planning, basic information on the past and present incidence of HIV infection is urgently needed.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Effect of zidovudine on survival of patients with AIDS in Australia.

Since the first case of AIDS in Australia was diagnosed in December 1982, there have been substantial improvements in the treatment of AIDS-related conditions. In particular, zidovudine was widely introduced into clinical practice in Australia in June 1987. In order to evaluate its effect, we compared the survival of patients diagnosed before and after July 31, 1987 using data available in early 1989. Survival distributions were compared by means of Kaplan-Meier curves and by fitting exponential survival models incorporating a special feature of the data. Before August 1, 1987 the overall distribution of survival times for patients with AIDS in Australia is well described by an exponential distribution with a mean of 1.04 years. The corresponding median survival time for this period was 8.8 months. For patients diagnosed with AIDS after July 31, 1987 the median survival time had not been attained by December 31, 1988. However, the estimated mean survival time increased to 2.7 years. Survival times were found to be remarkably stable over the different regions of Australia. We have shown that substantial improvements in survival of patients diagnosed with AIDS in Australia are associated with the widespread availability of zidovudine from mid 1987. To the best of our knowledge this study is the first of its kind to show a major shift in the distribution of survival associated with the introduction of antiviral therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Intense personal experiences: subjective effects, interpretations, and after-effects.

Following leads by Maslow (1964, 1968) and others who described peak experiences, this study was designed to learn more about the (1) subjective effects; (2) after-effects; and (3) interpretations of intense positive and negative experiences. Comparisons were made between respondents' "most positive" and "most negative" experiences and between these positive experiences and those of members of a yoga ashram. It was found that except for the differences in affect, positive and negative experiences were similar in subjective effects and impact on later life. The most positive experience of most respondents fell short of peak experience as described by Maslow. On the other hand, the most positive experience of ashram respondents showed evidence of a genuine alternation of consciousness and lasting life change afterward. The results suggest that only in rare instances is therapeutic change or self-actualization initiated by peak experiences. Implications are discussed.

Adaptation, Psychological↗
PubMed1990

Applications of simulated annealing to peptides.

We report the application of a new conformation searching algorithm called simulated annealing to the location of the global minimum energy conformation of peptides. Simulated annealing is a Metropolis Monte Carlo approach to conformation generation in which both the energy and temperature dependence of the Boltzmann distribution guides the search for the global minimum. Both uphill and downhill moves are possible, which allows the molecule to escape from local minima. Applications to the 20 natural amino acid "dipeptide models" as well as to polyalanines up to Ala80 are very successful in finding the lowest energy conformation. A history file of the simulated annealing process allows reconstruction and examination of the random walk around conformation space. A separate program, Conf-Gen, reads the history file and extracts all low-energy conformations visited during the run.

Algorithms↗
PubMed1990

Torsionally and hydrophobically modified 2,3-diarylindenes as estrogen receptor ligands.

2,3-Diarylindenes are ligands for the estrogen receptor which display intrinsic fluorescence. In order to optimize the receptor binding affinity of these compounds while preserving their desirable fluorescence properties, a series of torsionally modified analogues were prepared. A fluorine or methyl group was introduced on either of the two phenyl substituents ortho to their attachment site to the indene nucleus, in order to increase the out-of-plane twist of the appended rings. The analogues were prepared by the benzylation of appropriate deoxybenzoins, followed by Friedel-Crafts cyclic alkylation-dehydration. Comparison of the X-ray crystal structure of one analogue with unsubstituted analogues confirms the torsional perturbation effected by the ortho substituent. The torsional disposition of the C-2 aryl group in the substituted diphenylindenes is further investigated by UV (absorbance maxima and molar absorptivities), fluorescence (Stokes' shift), and NMR (chemical shifts). These spectroscopic measurements indicate increasing twisting between the C-2 aryl substituent and the indene system according to the following order: 3-ring o-Me-indene 9f less than diphenylindene 15 = 20 degrees less than 3-ring o-F-indene 9c less than 1-Me-indene 16 less than 2-ring o-F-indene 9b less than 2-ring o-Me-indene 9e = 63 degrees. The binding affinity of these analogues to the estrogen receptor was evaluated by a competitive radiometric receptor binding assay. While o-fluoro or o-methyl substitution on the 3-ring increases binding only slightly, binding of the o-fluoro 2-ring analogue is increased ca. 6-fold and the o-methyl analogue 11-fold, giving, in the latter case, a compound with an affinity equivalent to that of estradiol. The increase in binding affinity afforded by ortho substitution correlates with the increase in the torsion angle of the C-2 aryl ring. A thermodynamic evaluation of the receptor fit (Andrews, P. R.; Craik, D. J.; Martin, J. L. J. Med. Chem. 1984, 27, 1648) indicates that, for the o-methyl 2-ring analogue, the effect of the ortho substitution on increasing receptor binding appears to be a combination of increased surface area due to the substituent itself, together with a change in surface area of the ligand that results from the increased torsion of the two aryl rings. An o-fluoro substituent on the 2-ring provides a compromise between the relative planarity required for high fluorescence intensity and the molecular shape needed for increased estrogen receptor binding affinity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

A comparison of aztreonam/metronidazole and cefotaxime/metronidazole in elective colorectal surgery: antimicrobial prophylaxis must include gram-positive cover.

Aztreonam/metronidazole and cefotaxime/metronidazole were compared in a prospective trial in 154 patients undergoing elective colorectal surgery. Three antibiotic doses were given over 16 hours. A significant excess of wound sepsis in the aztreonam group was seen (23/71 vs 9/70 chi 2 6.60; P less than 0.01). Sepsis was almost invariably due to Gram-positive organisms and, in particular, Staphylococcus aureus.

Aztreonam↗
PubMed1990

The value of sonography in the diagnosis of acute diverticulitis of the colon.

To assess the value of sonography as the initial imaging procedure in patients suspected of having acute diverticulitis of the colon, we evaluated the sonograms of 71 patients who had clinical signs and symptoms of the disease. Identification of diverticula on sonograms was taken as evidence of acute diverticulitis. Fifty-four patients had sonographic findings consistent with this diagnosis. These included gut wall thickening (53), diverticula (34), pericolic (21) and intramural (two) fluid collections, edema of the pericolic fat (22), and intramural sinus tract (one). The final diagnosis was based on the clinical impression (all cases); pathologic interpretation of a surgical specimen (33 cases); findings on contrast enema (40 cases), CT scan (14 cases), and colonoscopy (18 cases); and a favorable clinical outcome in the absence of therapy (17 cases). Forty-six of the 54 patients with positive sonograms had acute diverticulitis, six had pericolic inflammatory masses caused by other colonic diseases, and two had surgically confirmed diverticulosis without active inflammation. All 17 patients with normal sonograms were treated conservatively. Diverticulitis was not confirmed in any of these patients. Our study suggests that sonography is a valuable imaging technique in the patient with signs and symptoms of acute diverticulitis.

Acute Disease↗
PubMed1990

Sonography accurately detects biliary obstruction in patients with surgically created biliary-enteric anastomosis.

The use of sonography to determine the patency of surgically created biliary-enteric anastomoses has been questioned by authors who favor use of cholescintigraphy and percutaneous transhepatic cholangiography for this purpose. We retrospectively reviewed the sonographic findings in 35 patients with such anastomoses: 16 choledochojejunostomies, 11 choledochoduodenostomies, five intrahepatic cholangiojejunostomies, and three cholecystoenterostomies. The anastomosis was patent in 25 patients, completely obstructed in four, and partially obstructed in six. Five of the 25 patients with patent anastomoses had nonanastomotic complications with biliary stasis and cholangitis. In the 20 patients with patent anastomoses and no complication, sonography showed bile ducts ranging from 2 to 9 mm in diameter filled with bile (six), gas (two), or both (12). No patient with a normally functioning anastomosis had evidence of a dilated bile-filled duct in the upright position. In four patients with complete obstruction of the anastomosis, sonography showed dilated, bile-filled ducts ranging from 6 to 14 mm in diameter proximal to the anastomosis. Sonograms in all six patients with partial obstruction showed both gas and bile in dilated bile ducts with superficial gas-filled ducts and dependent bile-filled ducts creating gas/fluid interfaces, which were persistent in the upright position. The 15 patients with anastomotic obstruction or other complication had confirmatory percutaneous transhepatic cholangiography (nine patients), scintigraphy (five patients), CT (four patients), and surgery (eight patients). Our experience suggests that sonography can be used to accurately assess surgically created biliary-enteric anastomoses for both anastomotic patency and for other complications.

Adult↗