Fixation of Bovine Pericardium-Based Tissue Biomaterial with Irreversible Chemistry Improves Biochemical and Biomechanical Properties.

Bioprosthetic heart valves (BHVs), derived from glutaraldehyde crosslinked (GLUT) porcine aortic valve leaflets or bovine pericardium (BP), are used to replace defective heart valves. However, valve failure can occur within 12-15 years due to calcification and/or progressive structural degeneration. We present a novel fabrication method that utilizes carbodiimide, neomycin trisulfate, and pentagalloyl glucose crosslinking chemistry (TRI) to better stabilize the extracellular matrix of BP. We demonstrate that TRI-treated BP is more compliant than GLUT-treated BP. GLUT-treated BP exhibited permanent geometric deformation and complete alteration of apparent mechanical properties when subjected to induced static strain. TRI BP, on the other hand, did not exhibit such permanent geometric deformations or significant alterations of apparent mechanical properties. TRI BP also exhibited better resistance to enzymatic degradation in vitro and calcification in vivo when implanted subcutaneously in juvenile rats for up to 30 days.

A case-control study of Hodgkin's disease in Israel.

Jewish residents of Israel in 1960-72 with Hodgkin's disease (HD) were compared with controls drawn from the general population. The controls were individually matched by sex, age, origin, and date of immigration. The comparison showed a significant association between HD and parental consanguinity and pointed to the possible etiologic role of recessive inheritance. Females with HD tended to have a lower parity than did their controls. Associations between HD and a high educational level and the presence of a flush toilet in the childhood home were significant and gave limited support to the hypothesis that a high standard of living in childhood increases the risk of subsequent HD. Tonsillectomy and a history of work with wood or trees were significantly associated with mixed cellularity but not with other histologic subtypes. Differences between patients with HD and controls with respect to cigarette smoking, exposure to animals, marital status, previous blood transfusions or jaundice, contact with asbestos, residual or occupational mobility, or other characteristics were not significant.

In-vivo stretch of term human fetal membranes.

INTRODUCTION: Fetal membranes (FM) usually fail prior to delivery during term labor, but occasionally fail at preterm gestation, precipitating preterm birth. To understand the FM biomechanical properties underlying these events, study of the baseline in-vivo stretch experienced by the FM is required. This study's objective was to utilize high resolution MRI imaging to determine in-vivo FM stretch. METHODS: Eight pregnant women (38.4 ± 0.4wks) underwent abdominal-pelvic MRI prior to (2.88 ± 0.83d) caesarean delivery. Software was utilized to determine the total FM in-vivo surface area (SA) and that of its components: placental disc and reflected FM. At delivery, the SA of the disc and FM in the relaxed state were measured. In-vivo (stretched) to delivered SA ratios were calculated. FM fragments were then biaxially stretched to determine the force required to re-stretch the FM back to in-vivo SA. RESULTS: Total FM SA, in-vivo vs delivered, was 2135.51 ± 108.47 cm(2) vs 842.59 ± 35.86 cm(2); reflected FM was 1778.42 ± 107.39 cm(2) vs 545.41 ± 22.90 cm(2), and disc was 357.10 ± 28.08 cm(2) vs 297.18 ± 22.14 cm(2). The ratio (in-vivo to in-vitro SA) of reflected FM was 3.26 ± 0.11 and disc was 1.22 ± 0.10. Reflected FM re-stretched to in-vivo SA generated a tension of 72.26 N/m, corresponding to approximate pressure of 15.4 mmHg. FM rupture occurred at 295.08 ± 31.73 N/m corresponding to approximate pressure of 34 mmHg. Physiological SA was 70% of that at rupture. DISCUSSION: FM are significantly distended in-vivo. FM collagen fibers were rapidly recruited once loaded and functioned near the failure state during in-vitro testing, suggesting that, in-vivo, minimal additional (beyond physiological) stretch may facilitate rapid, catastrophic failure.

Effect of Water Stress on Cortical Cell Division Rates within the Apical Meristem of Primary Roots of Maize.

We characterized the effect of water stress on cell division rates within the meristem of the primary root of maize (Zea mays L.) seedlings. As usual in growth kinematics, cell number density is found by counting the number of cells per small unit length of the root; growth velocity is the rate of displacement of a cellular particle found at a given distance from the apex; and the cell flux, representing the rate at which cells are moving past a spatial point, is defined as the product of velocity and cell number density. The local cell division rate is estimated by summing the derivative of cell density with respect to time, and the derivative of the cell flux with respect to distance. Relatively long (2-h) intervals were required for time-lapse photography to resolve growth velocity within the meristem. Water stress caused meristematic cells to be longer and reduced the rates of cell division, per unit length of tissue and per cell, throughout most of the meristem. Peak cell division rate was 8.2 cells mm-1 h-1 (0.10 cells cell-1 h-1) at 0.8 mm from the apex for cells under water stress, compared with 13 cells mm-1 h-1 (0.14 cells cell-1 h-1) at 1.0 mm for controls.

Psychotherapy in hospitalized research patients.

Operations at the clinical-research interface exert a signal influence on the therapy of patients being treated on investigative units. The effect on the treatment milieu has been described but the impact of a research climate on individual psychotheraphy of hospitalized patients has not. We observed research-therapy interaction in 25 acutely schizophrenic patients. Analytically oriented psychotherapy was carried out on a National Institutes of Health clinical research unit where drugs are only occasionally used, and patients are subjects in psychobiological investigation. The subtle, and often neglected, interplay between therapy and research is examined, with emphasis on the shifting meanings of the patient's participation or refusal to participate in therapy, research, or both. A research transference and countertransference are defined, and some special behavioral patterns of research patients receiving dynamic therapy are considered in this framework.

Schizophrenia and stimulus intensity control.

A group pf 19 acute, medication-free schizophrenic patients was studied, using average-evoked responses (AERs) to four intensities of light. Comparison with age- and sex-matched normal controls and patients with bipolar affective disorders showed that schizophrenics had smaller AER amplitudes and either no increase or an actual decrease in amplitude with increasing stimulus intensity. Normal subjects and schizophrenic patients were discriminated with 71% accuracy using AER variables; normals, patients with bipolar disorders, and schizophrenic patients with 64% accuracy. Patients who evidenced this AER "reducing" pattern to a noticeable extent early in hospitalization showed greater improvement and tended to have relatively good premorbid histories.

Seclusion: uses and complications.

A total of 7.2% of the patients in a private psychiatric hospital were placed in seclusion during a one-year study. These 63 patients had a more frequent diagnosis of schizophrenia and manic-depressive illness, manic type, than a comparison group. Significant intergroup differences in age and length of hospitalization became insignificant when the seclusion patients under 20 were excluded. Although seclusion was often used to protect patients, others, and property, the most frequent reason was to maintain a therapeutic environment. This study pointed toward a staff tendency to see the "problem" of the patient's behavior as being solved by seclusion rather than viewing seclusion as an intensive care environment in which the patient's behavior and treatment could be morec arefully monitored.

Functioning at the clinical-research interface: the clinical-research meeting.

The authors describe their experience in carrying out clinical and psychobiological research in a therapeutic milieu setting. The clinical-research meeting, composed of clinical-care staff with secondary research responsibilities, researchers, and acutely psychotic patients, proved to be a useful mechanism for identifying and resolving inevitable problems at the clinical-research interface and enhanced the effectiveness of research implementation and patient care. The authors discuss three specific areas where covert issues threatened to undermine the work of the unit-the abrogation of research responsibility, the abrogation of clinical responsibility, and intergroup competition and envy.

Applicants' choice of a residency training program.

The authors present results from a survey of senior medical students in the class of 1981 concerning their selection of residency training programs in psychiatry. Generally, students were more influenced by clinical training opportunities and quality of life factors and not much influenced by the philosophy of the program. The implications of the findings are discussed from the perspectives of both advising and recruiting medical students.

Undetected HIV infection among acutely ill psychiatric inpatients.

Serological testing of waste bloods revealed that 25 (7%) of 350 acutely ill psychiatric inpatients had HIV infection. Eight of the 10 HIV-positive patients whose serological status was not recorded on admission were discharged with their status still unrecorded and presumably undetected. Thirty-nine (51%) of the 77 inpatients with HIV-related risk behaviors identified on admission were discharged with no record of their having been serologically tested before or during hospitalization.

The medical student's perspective of psychiatry residency selection procedures.

To determine what factors influence medical students' perception of the application and selection procedures of psychiatric residency programs, the authors sent a questionnaire to 100 medical students interviewed for the residency program at a major psychiatric facility; 43 returned the forms. There was general concordance between the respondents' perception of the institution's selection criteria and their convictions regarding what those criteria ought to be, with the exception that applicants tended to downgrade the dean's letter. Factors important in the residents' evaluation were the warmth, enthusiasm, and interviewing skills of the faculty and residents. They did not object to psychologically probing interviews if the interviews were skillfully conducted. It was important to them that they met the chairman and program director, and if the applicant was a woman, she wanted to have at least one woman interviewer.

From supervisee to supervisor: an unexplored aspect of the psychiatrist's education.

The authors describe several problems that are unique to the beginning supervisor of psychiatry residents. These difficulties can be divided into four general areas: inexperience, competition, identity, and administration. The authors provide examples to illustrate the types of situations that the new supervisor may encounter and make recommendations for dealing effectively with them.

Psychiatric problems in third-year medical students.

Each year as many as one of four medical students experience sufficient emotional pain to seek psychiatric consultation. In many cases the precipitating stress relates to specific stresses associated with the phase of training. In the third year increased clinical responsibility may evoke feelings centered on caretaking, sexuality, and aggression that cannot be contained by an as yet fragile emerging professional identification. The authors present four case histories of third-year medical students to illustrate the complex interaction between family background, motivations to enter medicine, and the specific patient experience that resulted in sufficient distress to require psychiatric consultation.

Undetected HIV infection among patients admitted to an alcohol rehabilitation unit.

Of 300 patients admitted to an alcohol rehabilitation unit, serological testing of discarded admission blood samples revealed that 31 (10.3%) had HIV infection. Chart records indicated that four patients were known to be HIV infected on admission, and HIV infection was detected in another three patients during hospitalization; however, 24 (77.4%) of the HIV-positive patients were discharged with their HIV infection still undetected.

Medical students' learning as primary therapists or as participant/observers in a psychiatric clerkship.

The authors assessed two different inpatient models of clinical clerkships in psychiatry on the basis of both an examination assessing amount of learning and a survey of student attitudes. One clerkship model placed the third-year medical student in the role of primary therapist; the other model assigned each student to join a psychiatrist as a participant/observer. No overall difference in objective assessment of learning was found between the two groups of students, and student attitudes generally favored the participant/observer model. These findings suggest that the widespread bias favoring the primary therapist model may not be justified.

Bronchioloalveolar carcinoma and generalized amyloidosis complicating progressive systemic sclerosis.

We report a patient with progressive systemic sclerosis in whom an autopsy, performed 13 years after diagnosis, revealed the presence of bronchioloalveolar carcinoma and of generalized amyloidosis. Characterization of the amyloid fibril protein suggested an immunoglobulin light chain (AL) origin.

Clustering of Hodgkin's disease in Israel: a case-control study.

The geographical distribution of Jewish patients in Israel with HD diagnosed between 1960 and 1972 differed significantly from that of individually-matched population controls. Significant clustering occurred in 3 regions of the country. The odds ratio expressing the greater tendency of patients to have lived in one of these regions 5-9 years before the diagnosis, as compared with that of their paired controls, was 2.4. The association with residence in a higher-risk region was not significantly modified by sex, age, period of immigration, region of birth, father's region of birth, or date of diagnosis. The association was weaker for cases with nodular sclerosis than for those with other subtypes of HD. The clustering could not be explained by available data on the characteristics and prior experience of the cases and controls. There was a significant correlation between the risk of HD in a region and the proportion of native Israelis in its Jewish population, but there were no significant correlations with a variety of other demographic, natural and socioeconomic features of the regions. There was no significant time-space interaction. The findings suggest that susceptible people living in certain parts of the country during the 1950's and 1960's had a somewhat enhanced risk of HD because of exposure to unidentified environmental factors active in those regions at that time.

Effects of accelerated testing on porcine bioprosthetic heart valve fiber architecture.

We undertook the following study to quantitatively assess the changes in porcine bioprosthetic heart valve (PBHV) fiber architecture to increasing levels of fatigue damage using an in vitro accelerated test model. PBHVs were subjected to 0-500 million test cycles at 16 Hz, and small-angle light scattering (SALS) was used to quantify the gross fiber structure of the cusps. The degree of gross fiber alignment remained essentially constant from 0 to 500 million cycles over the entire cusp. Increasing fiber orientation randomness, indicative of local damage, was observed only in the vicinity of the nodulus of Arantii after 50 million cycles. The SALS data from the damaged regions suggested shearing between fiber layers, which may be part of the failure process and accelerates valve failure. Histological analysis revealed a relatively intact gross fiber structure with the collagen fiber crimp remaining, although delamination and de-registration of the crimp was also observed. Accelerated tested PBHVs also demonstrated a pronounced 'sagging', which began at the earliest cycle number tested (1.4 million cycles) and whose rate decreased logarithmically with cycle number. Results of this study suggest that PBHV cusps can alter their shape without any visually apparent material yielding or fiber failure under continual cyclic loading. Further, while most of the 4 mmHg pressure fixed PBHV's gross fiber architecture remains unchanged after 500 million cycles of accelerated testing, localized accumulated fiber damage can occur on a sub-visual structural level as early as 50 million cycles.

Apoptotic index as a prognostic factor in Hodgkin's disease.

Hodgkin's disease (HD) is an unusual malignant neoplasm, mainly because of the rarity of tumor cells in the diseased tissues, but also due to a relatively favorable response to treatment. In a previous study, we have shown a variable degree of apoptosis in lymph nodes from HD patients. We now looked for clinicopathological correlations of apoptosis with special emphasis on the prognosis in this disease. A retrospective study of 92 patients was carried out, using in situ end labelling of DNA fragments and an apoptosis detection kit. An apoptotic index (Al) was calculated in each case, as the percentage of apoptotic Hodgkin-Reed-Sternberg cells out of the total number of tumor cells in 10 selected high power fields. An association between a high Al and advanced stages was noted. A Kaplan-Meier analysis showed a negative correlation between Al and survival (p=0.05). In a multivariable analysis adjusting for Ann Arbor stage, a high Al carried a 3.27 fold risk of dying of HD (OR=3.27; Cl=0.89-11.94). However, in our limited cohort of HD patients, Al was not an independent prognostic factor. The results of this study confirm the important role played by apoptosis in HD and suggest that the apoptotic index is probably a negative prognostic marker in this disease. Its assessment in patients with HD may provide a new, important clinical tool.