Direct detection of nucleic acid hybridization on the surface of a charge coupled device

A method is described for the detection of DNA hybrids formed on a solid support, based upon the pairing of oligonucleotide chemistry and the technologies of electronic microdevice design. Surface matrices have been created in which oligonucleotide probes are covalently linked to a thin SiO2 film. 32P labeled target nucleic acid is then hybridized to this probe matrix under conditions of high stringency. The salient feature of the method is that to achieve the highest possible collection efficiency, the hybridization matrix is placed directly on the surface of a charge coupled device (CCD), which is used to detect 32P decay from hybridized target molecules (1, Eggers, M.D., Hogan, M.E., Reich, R.K., Lamture, J.B., Beattie, K.L., Hollis, M.A., Ehrilich, D.J., Kosicki, B.B., Shumaker, J.M., Varma, R.S., Burke, B.E., Murphy, A., and Rathman, D.D., (1993), Advances in DNA Sequencing Technology, Proc. SPIE, 1891, 13-26). Two implementations of the technology have been employed. The first involves direct attachment of the matrix to the surface of a CCD. The second involves attachment of the matrix to a disposible SiO2 coated chip, which is then placed face to face upon the CCD surface. As can be predicted from this favorable collection geometry and the known characteristics of a CCD, it is found that as measured by the time required to obtain equivalent signal to noise ratios, 32P detection speed by the direct CCD approach is at least 10 fold greater than can be obtained with a commercial gas phase array detector, and at least 100 fold greater than when X-ray film is used for 32P detection. Thus, it is shown that excellent quality hybridization signals can be obtained from a standard hybridization reaction, after only 1 second of CCD data acquisition.

The cooperative effects of TNF-alpha and IFN-gamma are determining factors in the ability of IL-10 to protect mice from lethal endotoxemia

Recent studies have demonstrated that interleukin-10 (IL-10) has the capacity to protect mice from the lethal effects of endotoxin. In this investigation, we have examined the ability of IL-10 to protect both normal mice and Corynebacterium parvum-primed mice against endotoxin lethality. In the overwhelming majority of experiments, recombinant murine IL-10 (rMuIL-10) and recombinant human IL-10 (rHuIL-10) did not protect normal BALB/cJ mice from lipopolysaccharide (LPS)-induced lethality at doses up to 10 micrograms/mouse. Despite their inability to protect, both IL-10 preparations were highly effective in preventing the increase in serum tumor necrosis factor alpha (TNF-alpha) that occurred in response to the lethal dose of LPS. Moreover, a neutralizing antibody against TNF-alpha gave only partial protection when administered alone to BALB/cJ mice. Treatment with a combination of neutralizing antibodies against TNF-alpha and interferon-gamma (IFN-gamma) resulted in complete protection. In contrast to BALB/cJ mice, normal BDF1 mice were protected from lethal endotoxemia by treatment with both rMuIL-10 and rHuIL-10. However, IL-10 did not protect C. parvum-primed BDF1 against LPS lethality even though it caused a reduction in the LPS-induced serum TNF-alpha response in C. parvum-primed mice as well as in normal BDF1 mice. Neutralizing antibodies against TNF-alpha and IFN-gamma were protective when administered alone to normal BDF1 mice, as previously demonstrated in C. parvum-primed mice. These findings suggest that lethal endotoxemia is a result of the cooperative activities of TNF-alpha and IFN-gamma in normal mice of the BALB/cJ and BDF1 strains as well as in C. parvum-primed BDF1 mice. IL-10 appears to be less effective in protecting mice from lethal endotoxemia when cooperation between IFN-gamma and TNF-alpha is facilitated by high-level production of the cytokines as in C. parvum-primed mice or when there is evidence of strong synergy between them as in normal BALB/cJ mice.

Performance-based assessment of moral reasoning and ethical judgment among medical students

BACKGROUND

An assessment technique was developed to measure the abilities of medical students to deal with moral and ethical issues.

METHOD

Assessments of ability in moral reasoning and ethical judgement were administered in July and August of 1991 and 1992 to 511 fourth-year students from five northeastern U.S. medical schools. Five behavioral parameters were measured during each student's encounter with a standardized patient (SP), who graded the student's performance. Immediately following the encounter, each student was asked to describe at least two moral conflicts in a short essay, which was graded by the authors of the study. Statistical analysis used chi-square, Fisher's exact test, and Spearman rank correlation.

RESULTS

Poor performance on the interactive tasks with the SP was observed among 11% of the students; on the written (analytical) tasks, among 14.1%; and on both portions of the assessment, among 2.3%. Little relationship existed between performances on the interactive and written portions.

CONCLUSION

That a low degree of relationship was found between the students' performances on the interactive and written portions of the assessment suggests that the two portions measure different skills. To address student differences, the authors formulated a model for categorizing students that would be useful in individualizing remedial strategies.

Medicaid policies for HIV-related drug therapies: perspectives of the state affiliates of the American Pharmaceutical Association

OBJECTIVES

To determine how Medicaid prescription drug policies differ by state, and to assess how these policies affect pharmacies and the drug therapies available to Medicaid patients with HIV infection or tuberculosis. EVALUATION PROCESS: The state affiliates of the American Pharmaceutical Association (APhA) were surveyed to learn how state Medicaid policies impact the provision of prescription drugs to Medicaid patients within their state. The survey focused on Medicaid payment level incentives, Medicaid payments compared with private payments, Medicaid utilization policies, and incentives and disincentives in each state's Medicaid payment system.

RESULTS

Approximately two-thirds of the APhA affiliates reported that the Medicaid payment levels in their states for drugs used to treat HIV-related illnesses were at least moderately below private payment levels; in 11 states these Medicaid payments were substantially below those of private payers. Many APhA affiliates responding to the survey stated that the Medicaid program in their state limited the number of reimbursed drugs that Medicaid patients can receive. Eight APhA affiliates reporting that these utilization limits created restrictions on the ability of Medicaid patients with AIDS and HIV-related infections to receive needed medications.

CONCLUSIONS

With Medicaid programs becoming the major payers of AIDS-related healthcare, federal policies should standardize Medicaid coverage, payment, and utilization policies for prescription drugs needed by Medicaid recipients with HIV-related conditions. This would enable Medicaid patients to receive necessary and adequate drug therapies regardless of their state of residence. These federally mandated policies also would require an increased federal role in financing this expanded Medicaid drug coverage.

Liability and mental health services

Under the current tort-malpractice system, mental health malpractice claims often harm defendants' reputations, disrupt relationships among providers, and breach patient confidentiality. Common areas of malpractice, together with difficulties in defining the standard of care and proving causation, are examined. Reform proposals involving the options of interdisciplinary compensation panels or binding arbitration are designed to protect plaintiff privacy, reduce time and cost of litigation, and increase satisfaction with the dispute resolution process.

Results of uncemented porous-coated anatomic total hip replacement

We reviewed a consecutive series of 241 uncemented, porous-coated anatomic (PCA) hip replacements at an average follow-up of five years (2 to 9). Of these, 32 had failed (13%), 26 at the acetabular component (11%) and six at the femoral component (2%). Acetabular failure was associated with local osteolysis and excessive polyethylene wear in 20 cases: in these histological examination showed giant macrophages incorporating numerous particles of high-density polyethylene. The femoral failures were related to a poor intramedullary fit with subsequent subsidence. Using the recommendation for revision as the end point, the cumulative survival rate for prostheses was 91% at six years (95% CI +/- 6%), 73% (+/- 11%) at seven years, and 57% (+/- 20%) at eight years. The result of uncemented PCA hip replacement is satisfactory up to six years, but then increasing failure of the acetabular component appears to be due to polyethylene wear, leading to osteolysis, loosening and component migration. At first, failure is often asymptomatic; routine follow-up of uncemented hip replacement is essential, especially after five years.

Medicaid policies for HIV-related prescription drugs

As State Medicaid programs become increasingly important sources of payment for acquired immunodeficiency syndrome (AIDS)-related care, and drug regimens the major weapons available to fight human immunodeficiency virus (HIV)-related illnesses, Medicaid drug policies will have a substantial impact. State Medicaid programs were surveyed to identify policies on a range of prescription drug policies affecting these recipients. All Medicaid programs provide prescription drug benefits to all categorically needy recipients, and about three-fourths of the States provide these benefits to medically needy recipients. However, utilization limits, copayments, and off-label-use and prior-authorization policies in many States weaken the drug benefit available.

The effect of using a pre-brushing mouthwash (Plax) on removal of tooth stain in vivo and in vitro

The aim of this study was to determine whether the use of a pre-brushing mouthwash Plax reduced extrinsic tooth-staining in vivo and in vitro. Firstly, in a double-blind placebo controlled cross-over study, 20 subjects with tooth staining used Plax or a placebo for 14-day periods separated by a 1-month wash-out period. The area of stain was assessed before and after each mouthwash had been used from clinical photographs. Secondly, extracted 3rd molar teeth were stained with tea and chlorhexidine. After exposure to either Plax or placebo, the teeth were brushed in a standardized manner. The area and intensity of stain were assessed before and after rinsing and brushing. Results of the study in vivo showed that the mean % stained area for any of the surfaces studied changed very little throughout the study. No statistically significant changes were detected (Student t-test, p > 0.05). Results of the study in vitro showed that the mean area of stain fell by 19% after exposure to Plax and by 17% after exposure to placebo. No statistically significant changes were detected (Student t-test, p > 0.05). There were also no significant changes in intensity (Wilcoxon signed rank sum test p > 0.1).

Effect of soil pH on availability to crops of metals in sewage sludge-treated soils. II. Cadmium uptake by crops and implications for human dietary intake

Appropriate pH-related permissible soil-limit concentrations for cadmium in sewage sludge-treated agricultural soils were estimated from the proportional changes in concentrations of cadmium in potatoes, oats and ryegrass grown on two sludge-amended soils and at different pH values. Implications for potential human dietary intake of cadmium were also assessed. Yields of crops increased with increasing soil pH, probably in response to decreasing uptake of zinc as soil pH value was raised. In general, cadmium concentrations in peeled potato tubers, potato peelings, oat straw and ryegrass decreased as simple linear functions of increasing soil pH over the range of pH values measured (pH 3.9-7.6). Cadmium concentrations in potato peel were particularly sensitive to changing pH conditions, whereas cadmium levels in oat grain were independent of soil pH. On the basis that a highly precautionary approach is adopted in setting soil standards for heavy metals, appropriate permissible concentrations of cadmium in sludge-treated agricultural soil which protect the human food chain were determined as 2.0 and 2.5 mg Cd Kg(-1) for banded pH ranges of 5.0-5.5 and 5.5-6.0, respectively.

Comparative mutagenicity of plant-activated aromatic amines using Salmonella strains with different acetyltransferase activities

Plant systems can activate aromatic amines into mutagens. In the plant cell/microbe coincubation assay, we earlier demonstrated that 2-aminofluorene and m-phenylenediamine were activated by plant cells into mutagens with reversion at the hisD3052 allele in Salmonella typhimurium strain TA98 as the genetic endpoint. New derivatives have been developed which possess elevated levels of acetyl-CoA:N-hydroxyarylamine O-acetyltransferase which are very sensitive to N-hydroxylated amines [Watanabe et al., 1990: Mutat Res 234:337-348]. The objectives of this research were to examine Salmonella strains with different acetyltransferase activities in the plant cell/microbe coincubation assay with a series of structurally related aromatic amines. The hypothesis tested was whether and to what degree a plant-activated metabolite of these aromatic amines could serve as a substrate for bacterial O-acetyltransferase and induce mutation in Salmonella. Every aromatic amine examined was activated by plant cells with YG1024 (the strain with elevated O-acetyltransferase activity) as the genetic indicator organism. The rank order of the mutagenic responses of YG1024 to the plant-activated aromatic amines was 2-aminofluorene > benzidine > m-phenylenediamine > 4-aminobiphenyl > 2,4-diaminotoluene > 2-naphthylamine. This rank order was expressed by TA98 but to a much lower degree. There was a very slight mutagenic response observed in TA98/1,8-DNP6 (a strain lacking O-acetyltransferase activity) with the plant-activated metabolites of benzidine and 4-aminobiphenyl. We conclude that the plant-activated aromatic amines are substrates for bacterial O-acetyltransferases.

Effect of soil pH on availability to crops of metals in sewage sludge-treated soils. I. Nickel, copper and zinc uptake and toxicity to ryegrass

The effect of soil pH value on concentrations of Ni, Cu and Zn in ryegrass grown on two sludge-treated soils was examined under field conditions and the maximum permissible soil limit values for these elements were determined which prevent phytotoxicity in crops where sewage sludge is applied to agricultural soils with pH <6.0. Concentrations of all the elements in ryegrass decreased as simple linear functions of increasing soil pH and this response was consistent across the range of pH values measured (pH 4.2-7.0). The response of individual elements tended to differ though, with Cu being less sensitive to changing pH conditions compared with Zn and Ni which responded in a similar manner. The yield of ryegrass also increased with increasing soil pH value probably due to the effects on Zn uptake as the crop content of Zn exceeded known upper critical tissue concentrations for this element at both sites. The proportional change in metal content of ryegrass at pH 5.0, 5.5 and 7.0 from tissue concentrations at pH 6.0 was calculated to determine the permissible soil concentration values on the basis of current maximum limits set by the Sludge Regulations in the UK for sludge-treated agricultural land at pH 6.0-7.0. The estimated permissible concentrations of Ni and Zn in soil corresponded with the regulatory values at the low pH ranges, but were substantially above the current soil limits at pH 7.0 indicating larger quantities of these elements could be safely applied under alkaline soil conditions. The estimated soil limits for Cu implied that the current Regulations were highly precautionary for this element.

Chronic thromboxane synthase inhibition with CGS 12970 in human cyclosporine nephrotoxicity

CsA nephrotoxicity in rats is associated with an increase in renal thromboxane production. Treatment with selective thromboxane synthase inhibitors or receptor antagonists improves renal function in these animal models. In humans, it is unclear whether intervention aimed at reducing the effects of thromboxane on the kidney will be clinically useful. However, we reported previously that thromboxane metabolite excretion is increased in CsA-treated renal allograft recipients with evidence of CsA toxicity and that 48-hr intravenous infusion of the selective thromboxane synthase inhibitor CGS 13080 improves renal function in such patients. We undertook the present study to determine the effect of more prolonged treatment with an oral thromboxane synthase inhibitor, CGS 12970, in renal transplant recipients taking CsA. We measured glomerular filtration rate and p-aminohippurate clearance before and after 4 weeks of treatment with CGS 12970 in 13 patients with renal allografts who had been treated with CsA for a mean 6.3 months and had mild renal insufficiency. Baseline serum creatinine was 1.8 +/- 0.3. Treatment with CGS 12970 resulted in 83% inhibition of urinary thromboxane B2 (TXB2), 93% inhibition of 2,3-dinor-TXB2, and 89% inhibition of 11-dehydro-TXB2, but no change in the urinary excretion of prostacyclin metabolites. However, suppression of urinary thromboxane metabolites to these levels did not significantly affect renal function. Glomerular filtration rate was 45 +/- 4 ml/min/1.73 m2 at baseline and 43 +/- 4 ml/min/1.73 m2 after 4 weeks of treatment with CGS 12970. Estimated renal plasma flow was 272 +/- 21 ml/min/1.73 m2 at baseline and 251 +/- 38 ml/min/1.73 m2 with thromboxane synthase inhibition. Thus, substantial suppression of thromboxane production with CGS 12970 did not improve renal function in CsA-treated renal allograft recipients.

Effect of low-dose aspirin on thromboxane production and the antihypertensive effect of captopril

Some of the antihypertensive effects of angiotensin-converting enzyme (ACE) inhibitors occur through nonangiotensin II-mediated mechanisms. One of these is through decreased kinin degradation, leading to enhanced production of vasodilator arachidonic acid metabolites. It was reasoned that if ACE inhibition also leads to an increase in the production of the potent vasoconstrictor thromboxane A2, then maneuvers that selectively inhibit thromboxane production without reducing prostaglandins (PG) E2 + PGI2 might enhance the antihypertensive effect of ACE inhibition. This double-blinded, randomized, crossover study was therefore undertaken to determine: (1) if captopril increases platelet and/or renal thromboxane production; and (2) if low-dose aspirin enhances the antihypertensive effect of captopril. Patients with mild essential hypertension and no other significant medical problems were studied. In a double-blinded, random order, patients took captopril alone (25 mg every 12 h) for 2 wk and captopril plus aspirin (75 mg/day) for another 2 wk. Active treatment periods were preceded by 2 wk of single-blind placebo. Fifteen patients with a mean age of 53 yr and an average mean arterial pressure (MAP) of 114 +/- 8 (+/- SD) mm Hg were studied. Serum thromboxane B2 was higher (P < 0.05) during treatment with captopril/placebo (600 +/- 46 (+/- SE) pg/mL) than during the two washout periods combined (420 +/- 57 and 553 +/- 78) and was lowest (P < 0.0005) during treatment with captopril/aspirin (302 +/- 36). Captopril treatment significantly increased the urinary excretion of PGE2 (P = 0.038). Captopril/placebo significantly lowered MAP (P < 0.05) to 105.0 +/- 3.7 mm Hg compared with the washout period. However, the addition of aspirin to captopril caused no additional lowering of MAP (105.2 +/- 2.8 mm Hg). It was concluded that treatment with captopril does increase platelet thromboxane production. However, lowering platelet thromboxane with low doses of aspirin may not enhance the antihypertensive effect of captopril.

Retroviral infection can abrogate the factor-dependency of hematopoietic cells by autocrine and non-autocrine mechanisms depending on the presence of a functional viral oncogene

The mechanisms responsible for abrogation of the growth factor-dependency of a hematopoietic cell line were investigated. FDC-P1 cells were infected with retroviral constructs containing the neo gene and either a wild-type or a temperature-sensitive v-src oncogene. v-srcwt abrogated the factor-dependency of these cells since each G418r colony gave rise to factor-independent cells and no autocrine growth factor activity was detected. Moreover, the vast majority (< 99%) of cells infected with the v-srcts mutant gave rise to conditional factor-independent cells. Therefore a functional v-src gene product was required for growth factor-independence which occurred by a non-autocrine mechanism. A minority of factor-independent cells which arose after v-srcts infection, grew at the non-permissive temperature and one-half secreted granulocyte/macrophage-colony stimulating factor (GM-CSF) which supports the growth of the parental cells. Since the v-srcts viral stock contained a helper virus, Murine Leukemia Virus (MuLV), the ability of this virus to relieve factor-dependency was examined. A low frequency of factor-independent transformants was recovered after MuLV infection and one-half secreted GM-CSF. Therefore, retroviruses such as MuLV which lack an oncogene, can transform cells by stimulating autocrine growth factor secretion. Subsequent experiments performed with helper-free v-src preparations indicated that they could abrogate factor-dependency directly by a non-autocrine mechanism. These results demonstrate that a hematopoietic cell line can be transformed by two different mechanisms after retroviral infection and may be relevant for understanding hematopoietic cell transformation after persistent viral infection.

The incidence of fatal pulmonary embolism after knee replacement with no prophylactic anticoagulation

We made a prospective study of the incidence of fatal pulmonary embolism in patients after total knee replacement with no prophylactic anticoagulation. There were 499 consecutive patients having 527 knee replacements. They all wore anti-thromboembolic stockings and were mobilised 48 hours after surgery. No patient was lost to follow-up. One patient died of pulmonary embolism 22 days after operation. There were no other deaths within three months of operation. The incidence of fatal pulmonary embolism was 0.19% (95% confidence interval: 0 to 0.6%). Fatal pulmonary embolism is rare after total knee replacement without prophylactic anticoagulation and the routine anticoagulation of these patients is of doubtful value.

Triple helix formation at distant sites: hybrid oligonucleotides containing a polymeric linker

An oligonucleotide hybrid is described which possesses two triple helix forming oligonucleotides which have been connected by a flexible polymeric linker chain. As a prototype, binding of this class of oligonucleotide to duplex DNA has been studied using a segment of the HSV-1 D-glycoprotein promoter, which possesses a pair of 12bp target sites for stable triple helix formation, separated by a duplex spacer region which is one helical turn long. Band shift and footprinting analysis show that such hybrids can bind to both 12bp elements simultaneously, if flexible linkers are included which are longer than 20-25 rotatable bonds. Molecular modeling confirms that a flexible polymeric linker as short as 22 rotatable bonds is enough to link the two distant segments of triple helix, providing that the linker element travels a path which is external to the helix grooves and parallel to the long helix axis.

Correlations between graduates' performances as first-year residents and their performances as medical students

PURPOSE

To correlate graduates' performances as first-year residents with their performances as medical students, particularly their performances as seniors on a clinical skills examination using standardized patients.

METHOD

Residency directors were asked to rate the first-year performances of the 232 graduates from the classes of 1989-1991 of the Brown University School of Medicine. Pearson correlation coefficients were calculated for the relationships between these ratings and the two scores (for data collection and interpersonal skills) that the graduates had received in their senior year on a clinical skills examination using standardized patients. Correlations were also calculated between the residency ratings and the graduates' preclinical and clinical course grades and scores on Parts I and II of the National Board of Medical Examiners (NBME) examination.

RESULTS

Ratings were returned and complete data were available for 203 (87.5%) of the graduates. Among all the parameters of medical school performance, the data-collection score on the clinical skills examination correlated best (.273) with performance as a first-year resident. The correlations between the residency ratings and scores on the NBME I and II were practically zero.

CONCLUSION

This comparatively strong correlation between the graduates' data-collection scores and their performance ratings as first-year residents suggests that performance-based assessments using standardized patients may be at least as good as--perhaps even better than--traditional methods of evaluating medical students in predicting their performances as first-year residents.

Retention of traditional premedical students in a medical career pathway compared with students in a combined baccalaureate-medical degree program

This study compared the retention in medical career pathways of students enrolled in a combined baccalaureate-medical degree program to traditional premedical students at Brown University. Whereas 84% of the combined-degree students went on to medical school, only 36% of the traditional premedical students did. Among underrepresented minority students, the proportions were 74% and 39%, respectively. Scholastic Aptitude Test (SAT) scores accounted for some of the difference, yet even when SAT scores were controlled using a multiple logistic regression model, students enrolled in the combined-degree program were more than eight times as likely to continue in a medical career pathway.

Pharmacist clinical intervention program

Our efforts have helped us demonstrate the positive impact of pharmaceutical care for patients. Our experience with the Clinical Notes section of our computer system leads us to recommend that such capabilities be sought in all pharmacy computer systems. A significant advantage to avoiding paper-based systems for documenting and collecting information relevant to clinical interventions, ADRs, DUE data, and patient outcomes has been proven in our institution. Various ways to categorize intervention data have been reported in the literature. We recommend clinical intervention categories be based on the eight categories of drug misadventuring so that data from different hospitals can be tabulated or compared. The success of our system is that it is one system rather than many systems. The importance of pharmacist documentation demands that it be simple, efficient, and painless, or it will be nonexistent.

Lipopolysaccharide-induced cytokine production and mortality in mice treated with Corynebacterium parvum

Tumor necrosis factor alpha (TNF-alpha) has been shown to be an important mediator of the lethal effects of endotoxin in several experimental models of septic shock. However, studies with a recombinant human interleukin-1 (IL-1) receptor antagonist protein (IL-1ra) suggest a role for IL-1 as a mediator of septic shock as well. In the present study, we show that mice treated in vivo with Corynebacterium parvum are primed for the production of interferon-gamma (IFN-gamma) and exhibit an enhanced capacity to produce serum IL-1 alpha, TNF-alpha, and IL-6 when challenged intravenously with lipopolysaccharide (LPS). The majority of C. parvum-treated mice die within 24 h of an LPS challenge. Pretreatment with a rat antimouse TNF-alpha monoclonal antibody (mAb) protected 90% of the animals against the lethal endotoxin challenge, while an anti-IFN-gamma mAb gave approximately 75% protection. The anti-IFN-gamma mAb also caused a reduction in LPS-induced serum TNF-alpha and IL-1 alpha. Anti-IL-1 alpha, anti-IL-1 beta, and anti-IL-6 neutralizing mAb did not protect against lethality when administered to mice prior to the LPS challenge. These results indicate that TNF-alpha and IFN-gamma are major mediators of endotoxin shock in C. parvum-treated mice. The results further suggest that the IFN-gamma produced by C. parvum-primed mice in response to an LPS challenge serves as a stimulus for enhanced production of TNF-alpha and IL-1 alpha. These findings are consistent with an increasing body of evidence suggesting a major role for IFN-gamma in lethal endotoxemia.