The polymorphism of HLA-DR3 in South African populations

The polymorphism of HLA-DR3 was investigated in families and unrelated individuals of three population groups: South African (SA) Negroes, Cape Coloureds and SA Caucasoids. Serological and restriction fragment length polymorphism (RFLP) analysis indicated that DR3 could be subdivided into DRw17 (previously DR3.1) and DRw18 (previously DR3.2). In contrast, the two-dimensional (2-D) gel electrophoresis patterns could not distinguish between the DRB1 gene products of the HLA-DRw17 and DRw18 cells. Two DRB3 variants, correlating with the T-cell defined specificities Dw24 and Dw25 were identified at the genomic and product level. Of ten haplotypes studied with the newly defined HLA-DRw18 specificity, all had the DRB3 RFLP pattern associated with Dw24. HLA-DRw17 was found in all three population groups tested, although in the SA Negroes HLA-DRw18 was the prevalent DR3 subgroup. This subgroup was also present in the Cape Coloureds but was absent in the SA Caucasoid tested. HLA-DRw18 forms part of the most characteristic SA Negro haplotype, Bw42, DQw4, Dw“RSH,” while HLA-DRw17 is part of the classic Caucasoid haplotype, B8, DQw2, Dw3.     

Student's perceptions of a virtual PBL experience.

OBJECTIVE: Our purpose is to present findings regarding student attitudes towards a virtual PBL program used to standardize their pediatric clinical experience. DESCRIPTION: With funding provided by the Fund for the Improvement of Post-Secondary Education, we developed Project LIVE (Learning through Interactive Video Education), a CD-ROM/Web hybrid program that uses digital video cases to conduct "virtual" problem-based learning groups with students doing a clinical rotation in a remote setting. Cases were progressively disclosed by videos of patient/physician encounters on a CD-ROM. Groups of five students and a faculty facilitator collaborated, teaching each other within the discussion section of the program. We conducted a multifaceted evaluation of Project LIVE to study the impact of case modality or distance on student learning and attitudes. We placed students in one of three groups (1) a face-to-face group with a paper case (FFT), (2) a face-to-face group with a video case (FFV), and (3) a virtual group (VG) with the digital video case. We then studied student attitudes about the three teaching formats. Over a six-month period three education specialists, who were not a part of the development team, conducted eight focus groups lasting one hour to assess student attitudes about Project LIVE. No one from the project team was present during these groups, and an independent evaluator analyzed the notes taken by each focus group leader. DISCUSSION: Trends across the groups included the following: (1) Authenticity (video)-Students reported that the authenticity of the case was a critical feature and that, "seeing (videos) made learning more memorable." Virtual and FFV groups reported more confidence in their ability to recognize abnormal findings in their patients. "You can't expect to teach clinical exam skills with a piece of paper." (2) Use of time-Students from all groups believed the cases were a good use of their time and improved their ability to solve clinical problems. They said it gave them an opportunity to "get away from just doing and focus on learning." However, the virtual groups complained of the lack of "a barometer for how much is too much" time. Some students reported spending an average of eight to ten hours per case over the period of a week. (In contrast, face-to-face groups met for three hours.) (3) Modeling clinical reasoning-Students believed the cases were valuable in structuring their knowledge, conceptualizing how to handle difficult situations, distinguishing abnormal from normal physical examination findings, and collaborating with their peers and their mentor to develop critical thinking. "It forced us to be logical" and ". how to think through the process-it mimics the real setting." (4) Technical support-The responsiveness of the Project LIVE staff was essential in assisting students in troubleshooting problems. (5) Distance component-Students preferred to work through the cases in face-to-face groups but agreed that the virtual experience is "good if you are in the middle of nowhere." This program was enjoyed by students and gave us an approach to standardizing experiences across multiple clinical sites.     

Influence of age on iminodipropionitrile-induced vestibular and neurobehavioral toxicities in rats

A direct association between aging and drug-induced dyskinesia has been reported by several investigators. Iminiodipropionitrile (IDPN), a prototype nitrile compound produces a motor syndrome in rodents, which resembles neuroleptic drug induced dyskinesia. In this investigation attempt has been made to study the effect of age on IDPN induced vestibular hair cell degeneration and resulting dyskinetic syndrome. Male Wistar rats aged 3, 6 and 12 weeks received IDPN in the doses of 0, 200 and 400 mg/kg, intraperitoneally for 3 consecutive days. IDPN-induced dyskinesia was assessed using a behavioral testing battery on days 3, 4, 5, 6, 7, 14, 21 and 28. The rats were sacrificed on day 28; temporal bones were excised for vestibular histopathology and sera were collected for measuring the indices of oxidative stress (glutathione and conjugated dienes). IDPN in the dose of 200 mg/kg produced dyskinesia in 12 weeks old rats, but failed to do so in 3 and 6 weeks old rats. The high dose of IDPN (400 mg/kg) caused dyskinesia in all age groups, however, its onset and severity were age-dependent. Older rats showed an early onset and significantly high incidence of dyskinesia as compared to younger rats. The susceptibility of rats to IDPN-induced behavioral deficits was proportional to oxidative stress and degeneration of sensory hair cells in the crista ampullaris.     

HIV-1 p24 antigen testing in blood banks: results from Saudi Arabia

HIV-1 p24 antigen testing was introduced to increase sensitivity in the early detection of HIV infection in blood donors. Since the introduction of HIV-1 p24 antigen testing in Saudi Arabia, we have failed to detect a single positive case. Over a three-year period, only four indeterminates were detected out of 24,654 blood donors. All four proved negative by confirmatory testing. Based on this experience, we believe that resources would be better directed to pooled nucleic acid testing and that p24 serological testing should be abandoned.     

Parameters influencing piezoelectric shock wave lithotripsy of biliary calculi

A total of 225 human gallbladder stones were divided into sets of two, three, or four identical calculi (with maximum diameters of 6-26 mm) and submitted to piezoelectric shock wave lithotripsy in vitro in order to investigate the influence of the following parameters on stone disintegration: shock wave intensity, pulse frequency, and various physicochemical parameters such as the volume and viscosity of the fluid surrounding the stone, the hardness of the calculus, and its chemical composition. The fragmentation efficacy increased with enhanced shock wave energy (P less than 0.01). If the volume of the fluid (30 mL) surrounding the calculus was small, the disintegration end-point (defined by maximum fragment diameters less than or equal to 4 mm) was achieved after a lower number of pulses (median: 250 pulses) than in the case of a large fluid volume (80 mL) (500 pulses; P less than 0.01). On the other hand, however, factors such as the shock wave pulse rate (0.9 Hz vs 1.6 Hz), variations in viscosity of a water-jelly mixture surrounding the stone, the chemical composition of the stones as determined by X-ray diffractometry, and stone hardness were found to have no significant influence on the fragmentation efficacy.     

Spatial games and the maintenance of cooperation.

The Prisoner's Dilemma (PD) is a widely employed metaphor for problems associated with the evolution of cooperative behavior. We have recently proposed an alternative approach to the PD, by exploring "spatial games" in which players--who are either pure cooperators, C, or pure defectors, D--interact with neighbors in some spatial array; in each generation, players add up the scores from all encounters, and in the next generation a given cell is retained by its previous owner or taken over by a neighbor, depending on who has the largest score. Over a wide range of the relevant parameters, we find that C and D persist together indefinitely (without any of the complex strategies that remember past encounters, and anticipate future ones, which characterize essentially all previous work on the iterated PD). Our earlier work, however, dealt with symmetric spatial lattices in two dimensions, deterministic winning and discrete time. We show here that the essential results remain valid in more realistic situations where the spatial distributions of cells are random in two or three dimensions, and where winning is partly probabilistic (rather than being determined by the largest local total). The essential results also remain valid (pace Huberman and Glance [Huberman, B. A. & Glance, N. S. (1993) Proc. Natl. Acad. Sci. USA 90, 7716-7718]) when interactions occur in continuous rather than discrete time.     

Fly me, I'm tropical

Leprosy, malaria and jigger fleas are all in a week's work for London's Hospital for Tropical Diseases. But some fear that the internal market could bring its 170-year history to a close, reports Annabelle May.     

Partnership to engage St. Louis high school students in investigative genetics.

The authors describe the Modern Genetics Project, based on a successful hands-on science implementation model that was developed and field-tested in St. Louis area high schools between 1992 and 1998. The project, begun in 1991, features a curriculum enhancement unit, "Modern Genetics for All Students," that combines strong scientific content, hands-on investigations, and human health applications, with reference to developing national and state science-teaching standards for this topic. The unit provides a significantly higher level of hands-on involvement throughout the school year for students than is found in traditional biology classrooms. This project aims to enhance scientific literacy among St. Louis high school students (all grades) of all learning levels and all socioeconomic, racial, and ethnic backgrounds; many of the students using the curriculum are from underrepresented minorities. This long-term project is carried out by a strong partnership among scientists at Washington University, implementation specialists from the Mathematics and Science Education Center of the Cooperating School Districts of St. Louis, project evaluators from Southern Illinois University at Edwardsville, and biology teachers at local high schools. Funding was originally from the National Institutes of Health and is now from the Howard Hughes Medical Institute. In 1998, there were 31 teachers and approximately 3,200 students participating in the project. Both quantitative and qualitative evaluations of the project during the 1995-96 and 1996-97 school years indicate that there were significant gains in knowledge and attitudes among the students of all racial, ethnic, and socioeconomic groups represented, and among both boys and girls.     

Surgical subspecialty block utilization and capacity planning: a minimal cost analysis model

BACKGROUND: Operational inefficiencies in the use of operating rooms (ORs) are hidden by traditional measures of OR utilization. To better detect these inefficiencies, the authors defined two new terms, underutilization and overutilization, and illustrated how these measures might be used to evaluate the use of surgical subspecialty ORs. The authors also described capacity planning (optimizing surgical subspecialty block time allotments) using a minimal cost analysis (MCA) model. METHODS: The authors evaluated post hoc all surgeries performed over 6 yr at a large teaching hospital. To prepare utilization estimates, surgical records were categorized relative to budgeted OR block time for each subspecialty. Surgical cases beginning and ending during budgeted OR block time were categorized as budgeted utilization, budgeted time not used for surgery was underutilization, and cases beginning before/after budgeted block time were classified as overutilization. Cases that overlapped budgeted and nonbudgeted OR block time were parsed and the portions were assigned appropriately. Probability distributions were fitted to the historical patterns of surgical demand, and MCA block time budgets were estimated that minimized the costs of underutilization and overutilization for each subspecialty. To illustrate the potential savings if these MCA budgets were implemented, the authors compared actual operational costs to the estimated MCA budget costs and expressed the savings as a percentage of actual costs. RESULTS: The authors analyzed data from 58,251 surgical cases and 10 surgical subspecialty blocks. Classic utilization for each block-day by surgical subspecialty ranged from 44-113%. Average daily block-specific underutilization ranged from 16 to 60%, whereas overutilization ranged from 4 to 49%. CONCLUSIONS: Underutilization and overutilization are important measures because they may be used to evaluate the quality of OR schedules and the efficiency of OR utilization. Overutilization and underutilization also allow capacity planning using an MCA model This study indicated that the potential savings, if the MCA budgets were to be implemented, would be significant.