The refractive group

Spherocylindrical optical elements can be decomposed into a sphere-equivalent component and two cross-cylinder components, oriented at 45 degrees to one another. These components in turn can be represented with a simple matrix formalism. This matrix formalism allows it to be seen that the components also form members of an eight element group, designated the refractive group. The structure of this group is developed including its algebra and its representation with Cayley diagrams. The group is identified as the eight element dihedral group, D4, and is compared to another well-known eight element group, the quaternion group. An example is given using the group formal algebra to develop the transfer equations for spherocylindrical wavefronts. Certain properties of propagating spherocylindrical wavefronts, such as nonrotation of cylinder axes, are seen to come directly as consequences of the group properties.

Cardiac allograft rejection: do trough cyclosporine levels correlate with the grade of histologic rejection?

BACKGROUND

The introduction of cyclosporine to heart transplantation immunosuppressive protocols has been associated with an improvement in the long- and short-term survival rates. The ideal dose of cyclosporine that maximizes its immunosuppressive properties and minimizes its toxicity has remained an enigma since its introduction. This study was undertaken to evaluate which range of cyclosporine levels provided the most effective protection against graft rejection.

METHODS

We studied the correlation between cyclosporine levels and histologic grade of rejection, cardiac function, and renal function by retrospectively analyzing the results of 1407 individual whole blood cyclosporine trough levels. One hundred seven heart transplant recipients were studied within 2 years of undergoing transplantation. As a historical comparison, we also studied 146 individual trough cyclosporine levels from a subgroup of patients (n = 14) who had acute cellular rejection with graft dysfunction or failure. We correlated trough cyclosporine levels with the histologic severity of cellular rejection, cardiac function (right cardiac catheterization), and serum creatinine in both groups. The correlation was performed within patient's own data rather than between patient groups to avoid interpatient variations.

RESULTS

The mean cyclosporine level was significantly higher (206 ng/ml) when the patients had grade 0 cellular rejection in comparison to grade 3A, with a mean cyclosporine level of 173 ng/ml (p = 0.005). Patients with graft dysfunction or failure had higher mean cyclosporine level (230 ng/ml) when they had no rejection compared with 3A rejection with a mean cyclosporine level of 153 ng/ml (p = 0.001). Furthermore, lower cyclosporine levels were associated with graft dysfunction. There was no correlation between serum creatinine and cyclosporine levels (r = 0.059, r2 = 0.351%).

CONCLUSION

We conclude that cyclosporine trough levels above 200 ng/ml in the first 2 years after heart transplantation are associated with reduced cellular rejection without deleterious effects on renal function.

Kinetics of splenocyte interleukin-4 production after injury and lethal endotoxin challenge

Cytokine aberrations may contribute to sepsis-associated mortality after trauma. We have previously documented that IL-10 (a Th-2 cytokine) is downregulated after tissue trauma, and the administration of exogenous IL-10 improved survival and anti-IL-10 antibody increased lethality in a murine injury-lethal endotox-emia model. IL-4 activates the Th-2 subset of T cells, and functions in a paracrine manner to inhibit proinflammatory cytokine synthesis. The purpose of this study was to investigate the kinetics of IL-4 production in this murine trauma-sepsis model. Mice (n = 50) were randomized to five groups: Control, Femur Fracture (FFx), FFx-lipopolysaccharide (LPS), FFx-LPS-IL10, and FFx-LPS-Anti-IL10. LPS (400 micrograms ip) was administered 4 days after FFx to induce lethal sepsis. IL-10 (0.5 microgram ip) or anti-IL-10 (100 micrograms IP) was administered at resuscitation, 30 min after LPS. IL-4 production was measured in ex vivo splenocyte culture supernatants at 24-hr intervals. Splenocyte IL-4 production was significantly upregulated in the FFx-LPS group that received anti-IL-10; maximal IL-4 production was on Day 5, with a greater than sevenfold increase compared to all other groups. A transient early rise in IL-4 production was noted in the FFx-LPS group that received exogenous IL-10; however, a subsequent rapid decline was documented. Treatment with anti-IL-10 antibody after FFx injury and septic challenge with LPS is associated with an upregulation of splenocyte IL-4 synthesis, as well as an increase in mortality in this murine model. IL-4 and IL-10 interaction postinjury may profoundly influence monocyte activation, cell-mediated immunity, and the subsequent host immune response to infection.

Blockade of CD28/B7 co-stimulation by mCTLA4-Hgamma1 inhibits antigen-induced lung eosinophilia but not Th2 cell development or recruitment in the lung

We have studied the role of the CD28/B7 co-stimulatory pathway in the development of a Th2-type lung immune response. Mice injected two or three times intraperitoneally with ovalbumin in alum adjuvant and then re-exposed to the same antigen by intranasal (i.n.) inoculation show infiltration of the lung tissue and appearance in the broncho-alveolar lavage (BAL) fluid of significant numbers of eosinophils and lymphocytes, in a pattern which is reminiscent of asthmatic inflammation. The accumulation of eosinophils in the airways is completely dependent on interleukin (IL)-5 secretion by CD4+ T cells. We have used mice transgenic for a soluble form of murine CTLA-4 (mCTLA4-Hgamma1) which binds to B7 molecules on antigen-presenting cells, thereby preventing their interaction with T cell-expressed CD28. mCTLA4-Hgamma1-transgenic mice immunized intraperitoneally and challenged i.n. with ovalbumin failed to generate any eosinophil infiltration, suggesting that little or no IL-5 was secreted in the lungs of these mice. In contrast with the complete lack of eosinophils, the numbers and phenotypes of infiltrating lymphocytes were comparable in the lungs of mCTLA4-Hgamma1-transgenic and normal mice. Also, lung lymphocytes from immunized mCTLA4-Hgamma1-transgenic and normal mice could be shown to secrete comparable amounts of IL-4 and IL-5 when stimulated in culture in the absence of mCTLA4-Hgamma1. We conclude that mCTLA4-Hgamma1 can efficiently block the production of IL-5 during in vivo responses and inhibit eosinophil recruitment, but that it does not block the development of CD4+ T cells into Th2 cells with the potential to secrete IL-5.

Spinal osteomyelitis presenting with a life-threatening pleural empyema

STUDY DESIGN

This case report illustrates a rare presentation of spinal osteomyelitis that initially manifested as a life-threatening pleural empyema leading to misdiagnosis.

OBJECTIVES

A high index of suspicion is required to make the correct diagnosis of spinal osteomyelitis, especially with unusual presentations. Appropriate antibiotic management should be commenced immediately the diagnosis is made.

SUMMARY OF BACKGROUND DATA

A review of the literature reveals five previous cases of vertebral osteomyelitis associated with pleural effusions. In three of these, the effusions were reactive and sterile. There is only one previous case of a pleural empyema related to primary spinal osteomyelitis. There also is one case report of vertebral osteomyelitis presenting as a mediastinal abscess.

METHODS

A case is presented of a man thought to have bronchogenic carcinoma with a destructive vertebral metastasis who was sent for palliative radiation therapy. A life-threatening pleural effusion subsequently developed, and after additional investigation, he was found to have spinal osteomyelitis with a pleural empyema.

RESULTS

The empyema was drained through an indwelling chest tube, and the patient was administered appropriate antibiotics. He made a complete and uneventful recovery.

CONCLUSIONS

The case illustrates a rare presentation of spinal osteomyelitis. It exemplifies the dictum that if a malignant disease is suspected, every effort has to be made to establish a histologic diagnosis to prevent inappropriate management and the potentially devastating consequences of an incorrect diagnosis. It also high-lights the difficulties in diagnosis of vertebral osteomyelitis with empyema. With correct management, the prognosis is excellent.

Mammalian mitochondria possess homologous DNA recombination activity

Mitochondrial protein extracts from normal and immortalized mammalian somatic cells catalyze homologous recombination of plasmid DNA substrates. Mitochondrial homologous recombination activity required exogenous adenosine triphosphate, although substantial activity remained when non-hydrolyzable analogs were used instead. There was no requirement for added nucleoside triphosphates, and the reaction was not inhibited by dideoxyadenosine triphosphate or aphidicolin. The majority of recombinant plasmid molecules result from a conservative process, indicating that nuclease-mediated strand-annealing is not responsible for the mitochondrial homologous recombination activity. Affinity-purified anti-recA antibodies inhibited the reaction, suggesting that activity is dependent on a mammalian mitochondrial homolog of the bacterial strand-transferase protein. The presence of homologous recombination activity within mammalian mitochondrial extracts suggests that this process is involved in mitochondrial DNA repair.

A phase III, multicenter, open-label, randomized, comparative study evaluating the effect of sevoflurane versus isoflurane on the maintenance of anesthesia in adult ASA class I, II, and III inpatients

STUDY OBJECTIVE

To compare the clinical efficacy and safety of sevoflurane and isoflurane when used for the maintenance of anesthesia in adult ASA I, II, and III inpatients undergoing surgical procedures of at least 1 hour's duration.

DESIGN

Phase III, randomized, open-label clinical trial.

SETTING

12 international surgical units.

PATIENTS

555 consenting inpatients undergoing surgeries of intermediate duration.

INTERVENTIONS

Subjects received either sevoflurane (n = 272) or isoflurane (n = 283) as their primary anesthetic drug, each administered in nitrous oxide (N2O) (up to 70%) and oxygen (O2) after an intravenous induction using thiopental and low-dose fentanyl. The concentration of volatile drug was kept relatively constant but some titration in response to clinical variable was permitted. Comparison of efficacy was based on observations made of the rapidly and ease of recovery from anesthesia and the frequency of untoward effects for the duration of anesthesia in the return of orientation. Safety was evaluated by monitoring adverse experiences, hematologic and non-laboratory testing, and physical assessments. In 25% of patients (all patients 171 both treatment groups at selected investigational sites), plasma inorganic fluoride concentrations were determined preoperatively, every 2 hours during maintenance, at the end of anesthesia, and at 1, 2, 4, 8, 12, 24, 48, and 72 hours postoperatively.

MEASUREMENTS AND MAIN RESULTS

Emergence, response to commands, orientation, and the first request for postoperative analgesia were all more rapid following discontinuation of sevoflurane than following discontinuation of isoflurane (sevoflurane, 11.0 +/- 0.6, 12.8 +/- 0.7, 17.2 +/- 0.9, 46.1 +/- 3.0 minutes, respectively, versus isoflurane, 16.4 +/- 0.6, 18.4 +/- 0.7, 24.7 +/- 0.9, 55.4 +/- 3.2 minutes). The incidence of adverse experiences was similar for sevoflurane and isoflurane patients. Forty-eight percent of patients on the sevoflurane group had no untoward effect versus 39% in the isoflurane group. Three patients who received sevoflurane had serum inorganic fluoride levels 50 microM/I. or greater though standard tests indicated no evidence of associated renal dysfunction.

CONCLUSION

Sevoflurane anesthesia, as compared with isoflurane, may be advantageous in providing a smoother clinical course with a more rapid recover.

Characterization of homologous DNA recombination activity in normal and immortal mammalian cells

Homologous DNA recombination levels were measured in normal and spontaneously immortalized murine and human fibroblasts, and in a number of primate and murine established fibroblast cell lines. Immortal cell lines and tumor-derived clones homologously recombined extrachromosomal plasmid substrates at frequencies approximately 100-fold higher than did normal cells. To further explore the mechanism responsible for this phenotype, homologous recombination frequency was measured using nuclear extracts derived from normal and immortalized murine and human fibroblasts. Extracts prepared from immortal cells catalyzed high levels of homologous recombination, whereas very little recombination activity was detected in extracts prepared from normal fibroblasts. Similarly, only extracts derived from immortal cells contained strand-transferase activity as measured by the recently described pairing-on-membrane assay. Mixing experiments indicated that a recombination enhancing factor or factors present in immortal cells, rather than a recombination inhibitor in normal cells, was responsible for the enhanced homologous recombination activity observed using extracts derived from the former.

Breastfeeding and health in the Western world

Considerable evidence suggests that infant feeding practices are associated with variations in health. This paper reviews research relating to the health of infants who receive breast milk, and of women who breastfeed, in the developed world. Obstacles to breastfeeding are examined, and current initiatives to increase breastfeeding levels are discussed.

Prevalence and impact of exposure to interpersonal violence among suburban and urban middle school students

OBJECTIVE

The purpose of this study was to determine the prevalence of exposure to violence in preadolescent children in communities that vary by family income and to determine patterns of physical symptomatology and communication after exposure to a traumatic event.

METHODS

Two hundred twenty-eight sixth-grade students from a suburban middle school (school A) and 209 sixth-grade students from an urban middle school (school B) in the Philadelphia metropolitan area were surveyed by a group-administered anonymous questionnaire.

RESULTS

Two hundred two students (89%) from school A and 200 students (96%) from school B reported knowing someone who had been robbed, beaten, stabbed, shot, or murdered. One hundred twenty-nine students (57%) and 183 students (88%), respectively, witnessed a robbing, beating, stabbing, shooting, or murder. Ninety-one students (40%) and 141 students (67%) had been personally robbed, beaten up, stabbed, shot, or caught in gun cross fire. One hundred thirty-four (59%) and 152 (73%) reported hearing gunfire in their neighborhood. One hundred eighty-eight (82%) and 202 (97%) had at least one positive response in all three categories: knowing a victim, witnessing an event, and being a victim of violence. The proportion of positive responses from school B was significantly greater than the proportion from school A for all of these results. Many students reported symptoms associated with somatization syndromes, depression, and posttraumatic stress disorder; the school B group had significantly more symptoms than the school A group. Both student groups had discussed episodes of witnessing an event or victimization with others, mostly family members and friends, and expressed feelings of fear, anger, sadness, and frustration about these episodes. A very low percentage of the students (from 1% to 8% in the different analyses) consulted a medical or mental health professional.

CONCLUSIONS

These data support a substantial prevalence or exposure to violence for suburban and, even more dramatically, for urban middle school-aged children. The higher-prevalence group reported a higher incidence of symptoms sometimes seen after traumatic stress. Many students in both groups expressed multiple feelings about their exposure to violence, and most talked to someone about their exposure; rarely was this person a health professional.

Use of sodium hetastarch (Hespan) solution for reduction of postoperative adhesion formation in rabbits

A study was conducted to determine the effect of sodium hydroxy ethyl starch (Hespan) on primary adhesion formation in a rabbit model. Hespan is a readily available volume expander. This was a randomized, double-blinded animal model in which New Zealand white rabbits were subjected to midline celiotomy. Adhesions were created by abrasion in both uterine horns, adjacent bowel, and peritoneum. Necropsies were performed at the 2-week interval and adhesions were graded. Significant decreases in type II and type III adhesions (p = .032 and p = .020, respectively) were demonstrated in Hespan-treated animals. Sodium hetastarch appears to decrease significant adhesion formation in treated animals and may have a role as an adjunct for postsurgical prevention.

Assessment of clinical decision-making ability of critical care nurses

What are nurse administrators to do when their institution is in need of competent nurses to staff the ICU and the majority of applicants are either inexperienced or new graduates? Nurses from one institution grappled with this question. They decided that it was their job to teach novice nurses to make sound clinical judgments in life-threatening situations. As part of this process, they developed a Clinical Decision-Making Assessment (CDMA) tool. This article describes the CDMA and provides suggestions for classroom and clinical teaching.

Anabolic-androgenic steroid use among 133 prisoners

We performed a forensic evaluation of a 16-year-old boy convicted of murdering his 14-year-old girlfriend while he was taking anabolic steroids. Prior to steroid use, he had displayed no features of antisocial personality disorder and no criminal record. Prompted by this index case, we interviewed 133 consecutive male convicts at the same facility where this boy was incarcerated to assess whether steroid use frequently contributed to criminal acts. Two other cases of apparent steroid-induced crimes were found in this cohort, suggesting that steroid use is an uncommon, though occasionally significant, factor in criminal behavior.

Elevated levels of recombinational DNA repair in human somatic cells expressing the Saccharomyces cerevisiae RAD52 gene

The Saccharomyces cerevisiae RAD52 gene was introduced into the human fibrosarcoma-derived cell line HT1080. Transfected cell lines that expressed the yeast transgene catalyzed inter-plasmid homologous DNA recombination at frequencies approx. 12-fold higher than did control cells. Additional experiments revealed that yeast RAD52 gene expression increased the level of resistance to the DNA damaging agents diepoxybutane, and methyl methanesulfonate, but did not alter sensitivity to ultraviolet radiation. These results indicate that the S. cerevisiae Rad52 protein can function in a human somatic cell background and provide support for the idea that a homologous recombination-based DNA repair process functions in mammalian somatic cells.

Financial performance of safety-net hospitals in a changing health care environment

Safety-net hospitals serving the poor and indigent in inner-cities have received inadequate research attention regarding the determinants of their financial performance in the changing health care environment. We analyze how the 1990-92 financial performance of 275 such hospitals is related to exogenous and endogenous factors such as payer mix, service mix, staffing and ownership. Models of hospital financial performance are developed using operating margin, cost per discharge and revenue per discharge as measures of performance. Stepwise regression is used to test the model with data from the American Hospital Association (AHA) and Health Care Investment Analysts (HCIA). Results suggest that: 1) The profitability of inner-city hospitals appears positively related with technical complexity of care; 2) High interest and low operating surplus may constrain the addition of technically sophisticated services to enhance profitability; 3) There is some evidence that new governmental programs, e.g. Medicaid managed care and Medicaid Diagnosis Related Groups (DRGs), may not have improved operating margins, though Medicaid DRGs appear to have contained costs. Follow-up research is needed on this issue; 4) Given external fiscal realities, internal management strategies for inner-city hospitals require research, e.g. developing appropriate managed care systems and timely expansion of sub-acute services and; 5) Services such as AIDS treatment and community health education represent opportunities to respond to community needs, especially since unit cost of such services will decline with high volume.

[Initial experience with the PCDiary: software for physicians for documenting and evaluating individual learning]

A computer diary was developed for physicians to create a portfolio of their self-directed learning. Each item of learning is recorded in the form of a question along with the stimulus, the learning resources used and the outcome planned for the learning. The records of 123 physicians which volunteered to use the diary were analyzed. Their response to the software, elicited by survey, is described. Items of learning were most often stimulated by scanning the literature and while seeking information to manage a patient. The physicians recorded their intent to change their practice as the outcome to learning most often when the learning was stimulated while managing a patient. One-half of the physicians reported that keeping the diary made them think about their patient care.

Effects of a child abuse prevention unit in health classes in four schools

The purpose of this study was to assess changes in parenting attitudes among high school students as an effect of a child abuse prevention unit taught in a required health class. Attitudes were measured using the Adult-Adolescent Parenting Inventory (AAPI), which was administered as a pretest-posttest. This was a primary prevention approach targeting students before they become parents. The unit consisted of an overview of child abuse, normal developmental expectations of children, anger management, and positive parenting techniques. Students from 4 schools participated in the study, and most students in the sample (N = 585) demonstrated healthy parenting attitudes. Low scores on multiple scales at pretest were recorded for 3.6% of the sample. Effect of intervention was measured using paired t tests, and a positive and statistically significant effect of intervention was noted, especially in 2 of 4 schools. Low-scoring students increased scores significantly although not up to mean pretest levels for the whole sample. Recommendations for further community health nursing research and educational initiatives are supported by these findings.

Cloning and characterization of HuR, a ubiquitously expressed Elav-like protein

The neuronal-specific Elav-like proteins (HuD, Hel-N, and HuC) contain three RNP-type concensus motifs and bind to AU-rich elements. We have identified and cloned a fourth member of this family (HuR) that is expressed in a wide variety of cell types. The purified recombinant protein binds avidly to the AU-rich element in c-fos and interleukin-3 mRNAs. In the case of the c-fos AU-rich element, HuR binds to a core element of 27 nucleotides that contain AUUUA, AUUUUA, and AUUUUUA motifs. Mutational analysis has shown that all three AU motifs are required for maximal binding.

Phase I/II trial of biweekly paclitaxel and cisplatin in the treatment of metastatic breast cancer

PURPOSE

To determine the maximum-tolerated dose of escalating doses of paclitaxel (Taxol; Bristol-Myers Squibb, Princeton, NJ) administered biweekly with a fixed dose of cisplatin, to assess the toxicity, and to evaluate the activity of this combination in a phase I/II trial in metastatic breast cancer.

PATIENTS AND METHODS

Twenty-nine women with metastatic breast cancer were enrolled; 27 were assessable for response and 29 for toxicity. All but two of the women had received prior adjuvant chemotherapy, with 23 receiving anthracyclines and six previous cisplatin.

RESULTS

The initial starting dose of paclitxel 90 mg/m2 and cisplatin 60 mg/m2 became the phase II dose due to dose-limiting neutropenia. Responses were seen in 85% of assessable patients, with three patients (11%) achieving a complete response (CR) and 20 patients (14%) a partial response (PR), for an overall response rate of 85% (95% confidence interval [CI], 66% to 96%). The time to disease progression for patients who achieved a CR was 110 to 200 days, and for those with a PR, it was 96 to 377+ days, with a median time to progression of 7.1 months and a median response duration of 7.9 months. Sites of CR were skin, soft tissue, and lung, and all occurred in women with previous exposure to anthracyclines. Septic events were rare, with two grade 3 infections (7%), only one of which required hospital admission. There were no grade 4 nonhematologic toxicity and minimal grade 3 toxicity. A total of 251 chemotherapy cycles were given -- 16 with paclitaxel alone in five patients. Forty-five percent of patients required dose reductions, while 52% had delays due to neutropenia.

CONCLUSION

Biweekly paclitaxel and cisplatin is an active combination in the treatment of metastatic breast cancer, including for patients with previous exposure to anthracyclines.

Identification of a human RAD52 pseudogene located on chromosome 2

A human testis cDNA library was screened with a hybridization probe encoding the mouse RAD52 gene. Two classes of clones were identified, one derived from the human RAD52 homolog (hRAD52), the other derived from a pseudogene. In addition to many point mutations, several of which encode stop codons, the pseudogene contains a number of frame shifts and a 103-bp deletion. We further determined that the pseudogene is processed and is located on human chromosome 2, in contrast to hRAD52 which is found on chromosome 12. Reverse transcription-PCR analysis of cultured human diploid fibroblasts, as well as fibrosarcoma cells, revealed that while hRAD52 is expressed at low, but detectable levels in these cells, the pseudogene is not.

A death in the family: household structure and mortality in rural Liaoning: life-event and time-series analysis, 1792-1867

"Through a discrete-time life-event analysis of triennial household register data from a northeast Chinese village, Daoyi, between 1774 and 1873, we find that an individual's probability of dying, which we treat as an indicator of access to resources and the nature of household roles, was affected by the composition of their coresident kin.... Widows and widowers had higher mortality than the currently married. Orphans had higher mortality than children with at least one parent present. Reflecting the dependence of a wife's status on whether she had produced an heir for her husband, married women in young adulthood and middle age who had at least one son had substantially lower mortality than those without. Reflecting the strength of the claim that elderly males could make on household resources, children with coresident grandfathers had higher mortality than those without. Even though sons were supposed to be a form of old-age security, however, the death rate of the elderly was not reduced by the presence of sons and grandsons."