Mechanical ventilation: past and present

BACKGROUND: Early stages of cutaneous T-cell lymphoma (CTCL) may be difficult to distinguish from benign inflammatory dermatoses by routine histologic examination. OBJECTIVE: Our purpose was to determine whether clonal rearrangements of the T-cell receptor (TCR) gamma gene by polymerase chain reaction and denaturing gradient gel electrophoresis (PCR/DGGE) could be detected in the early stages of CTCL and to correlate these findings with conventional histopathology. METHODS: A total of 39 specimens from 12 patients with CTCL were obtained. The slides were evaluated independently by three dermatopathologists, and categorized into three groups: nondiagnostic, suggestive of CTCL, and diagnostic of CTCL. Of the 39 specimens, 33 were tested by PCR/DGGE by means of GC-clamped primers for clonal rearrangement of the TCR gamma gene. RESULTS: The histologic evaluation of the 12 cases showed a significant variation among the three dermatopathologists. The correlation of PCR/DGGE with routine histology was as follows: Clonal TCR gamma gene rearrangements were demonstrated in 73% of the specimens nondiagnostic for CTCL, 71% of those suggestive of CTCL, and 74% of those diagnostic of CTCL. CONCLUSION: Clonal TCR gamma gene rearrangements may be detected in patients with early CTCL, even when the histologic findings are not unequivocally diagnostic. In patients with multiple biopsy specimens, identical clones were demonstrated in all rearranged samples, indicating the same neoplastic clone was present in the earliest stages of disease.     

Pitfalls in estimating motion detector receptive field geometry

A number of psychophysical investigations have used spatial-summation methods to estimate the receptive field (RF) geometry of motion detectors by exploring how psychophysical thresholds change with stimulus height and/or width. This approach is based on the idea that an observer's ability to detect motion direction is strongly determined by the relationship between the stimulus geometry (height and width) and the RF of the activated motion detectors. Our results show that previous estimates of RF geometry can depend significantly on stimulus position in the visual field as well as on the stimulus height-to-width ratio. The data further show that RF estimates depend on the stimulus in a manner that is inconsistent with basic predictions derived from current motion detector models. Hence previous estimates of height, width, and height-to-width ratios of motion detector RFs are inaccurate and unreliable. This inaccuracy/unreliability is attributed to a number of sources. These include incorrect fixed-parameter values in model fits, as well as the confounding of physiological spatial summation area through combined use of contrast thresholds and Gaussian-windowed stimuli. A third source of error is an asymmetric variation of spatiotemporal correlation in the stimulus as either its height or width is varied (and the other dimension held constant). Most importantly, a fourth source of unreliability is attributed to the existence of a nonlinear, nonmonotonic distribution of motion detectors in the visual field that has been previously described and is a natural result of visual anatomy.     

Coronary revascularization after myocardial infarction in the very elderly: outcomes and long-term follow-up

OBJECTIVE: To determine the outcome of very elderly patients who had coronary revascularization during hospitalization for an acute myocardial infarction. DESIGN: Retrospective cohort study. SETTING: Community-based tertiary-care teaching hospital. PATIENTS: A total of 1215 consecutive patients 80 years and older were hospitalized with a myocardial infarction between 1985 and 1990. The study sample included all 93 patients (8%) who had cardiac catheterization before discharge and had not been excluded from study because of the following: severe valvular disease, absence of significant coronary disease, or death before a decision about revascularization could be made. MEASUREMENTS: Survival, quality of life, and functional status at least 1 year after discharge. RESULTS: After catheterization, 41 patients had angioplasty, 18 had coronary artery bypass surgery, and 34 did not have revascularization. Among the patients alive at discharge, those who had revascularization had a high likelihood of achieving a good or excellent quality of life (angioplasty, 86% [31 of 36]; surgery, 89% [16 of 18]; medical therapy, 44% [11 of 25]) and of being able to care for themselves (angioplasty, 89% [32 of 36], surgery, 89% [16 of 18], medical therapy, 52% [13 of 25]). Mortality rates at 1 year were 24% (95% CI, 15% to 47%) for the angioplasty group, 6% (CI, 0% to 27%) for the surgery group, and 44% (CI, 27% to 62%) for the medical therapy group. In a Cox proportional hazards model that adjusted for clinical, demographic, hemodynamic, and anatomic differences between the groups, the performance of coronary revascularization was associated with increased survival (hazard ratio, 0.42; CI, 0.18 to 0.98). CONCLUSIONS: A small percentage of very elderly patients with complicated acute myocardial infarctions, selected by their physicians for invasive cardiovascular procedures, can tolerate these procedures, avoid serious complications, return to independent living, and have excellent probability of survival. Although our results suggest that coronary revascularization may have benefited these patients, the study design did not permit definite conclusions, and future studies are needed to resolve this important question.     

Evaluation of subcutaneous chambers as an alternative to conventional methods of antibody production in chickens

We compared antibody levels among serum, egg yolk extract, and granuloma fluid in chickens immunized with bovine serum albumin (BSA). One group of hens was immunized by intramuscular and subcutaneous injection of bovine serum albumin in complete Freund's adjuvant, followed by two subsequent booster injections in incomplete Freund's adjuvant. Two other groups were surgically implanted with plastic, perforated wiffle balls (subcutaneous chambers). After a 30-day recovery period, one of the groups with subcutaneous chambers was immunized with BSA in sterile water with two subsequent boosts. The other group was injected with only sterile water. Serum samples, eggs, and granuloma fluid were collected biweekly and analyzed to determine specific IgG, total IgG, and total protein. The subcutaneous chambers were well tolerated. Quantitative ELISAs of serum, egg yolk extract, and granuloma fluid specimens disclosed that specific antibody levels were present in all specimens by 2 weeks after primary immunization. During the course of the experiment, specific antibody levels of serum and egg yolk specimens were significantly higher than those of granuloma fluid (P less than 0.05). However, an additional injection of antigen into the subcutaneous chambers resulted in specific antibody levels in granuloma fluid specimens that were comparable to those of serum and egg yolk extract. Use of subcutaneous chambers in chickens may be a viable alternative to routine antibody production methods.     

Laminin 5 can promote assembly of the lamina densa in the skin equivalent model

Skin equivalents were prepared by culturing human keratinocytes on the surface of type I collagen gel contracted by human skin fibroblasts (dermal equivalents) and by raising the gel to an air-liquid interface. A stratified squamous epithelium was formed with a well-differentiated cornified layer at the top of keratinocyte layers within 7 days after plating of the keratinocytes on the dermal equivalents. Although major basement membrane components such as collagens IV and VII and laminin 5 were detected immunohistochemically at the dermal-epidermal junction, a lamina densa was rarely observed by electron microscopy even in 14-day skin equivalents. When laminin 5 (1, 5 or 20 microg/ml) was added to the culture medium on day 7 through day 14, types IV and VII collagens at the dermal-epidermal junction stained more strongly by immunohistochemistry compared with the control. Patches of lamina densa were present along the epidermal-dermal junction, and vesicles containing electron-opaque sheets approximately 0.6 microm in diameter that reacted with anti-collagen IV antibody were also observed in basal keratinocytes in 14-day skin equivalents by electron microscopy. Morphometric analysis showed that the total length of lamina densa along the dermal-epidermal junction as well as in the vesicles increased up to 180%, 230% or 520% of control cultures by the addition of laminin 5 (1, 5 or 20 microg/ml, respectively). These results suggest that laminin 5 accelerates formation of the lamina densa along the dermal-epidermal junction of the skin equivalents, depending on the concentration of laminin 5 supplemented exogenously.     

Acute skier's thumb repaired with a proximal phalanx suture anchor

The purpose of this study was to determine the functional outcome of a surgical technique for the repair of injuries of the ulnar collateral ligament of the thumb. A 14-point questionnaire was developed to determine functional outcome after surgical repair of acute ulnar collateral ligament rupture. Early ulnar collateral ligament repair was performed on 58 patients with grade III sprains (complete rupture) of the ligament using a new technique that employs a suture anchor for fixation. Forty-five patients were interviewed at a minimum postoperative interval of 12 months and were included in this study. Forty-four patients (98%) believed they had a stable repair, were satisfied with their surgery, and would have it again if necessary. Forty-four patients (98%) were not hindered in their day-to-day activities and had a functional range of motion. Mild discomfort was felt by eight of our patients (17%), but only three patients (7%) had pain with activities. The average time to return to skiing was 1.7 days. The use of a suture anchor provided a strong and stable repair if the surgery was performed early.     

Augmented inflammatory responses and altered wound healing in cathepsin G-deficient mice

BACKGROUND: Cathepsin G is a neutral serine proteinase that exists primarily in azurophilic granules of neutrophils, but also as a proteolytically active membrane-bound form. While the specificity and many in vitro biological activities have been described for cathepsin G, little is known about the role of this enzyme in neutrophil function in vivo, particularly as it applies to the wound-healing process. OBJECTIVE: To determine the role of cathepsin G in cutaneous tissue repair by examination of full-thickness incisional wound healing in mice with a null mutation for cathepsin G. METHODS: Paired, full-thickness linear incisions were made on the backs of cathepsin G +/+ and cathepsin G -/- mice, and wound tissue was harvested at days 1, 2, 3, 5, 7, 10, and 14 after wounding. Neutrophil influx, myeloperoxidase activity, and migration were examined using light microscopy, the myeloperoxidase assay, and modified Boyden chamber technique, respectively. Wound-breaking strength was measured using tensiometry. RESULTS: The absence of cathepsin G led to a 42% decrease in wound-breaking strength at day 7 after wounding (n=28; P<.002), which returned to the level of control mice by day 10 after wounding. Wound tissue sections in mice lacking cathepsin G also showed a 26% increase in neutrophil myeloperoxidase activity (n=12; P=.001) and an 18% increase in neutrophil influx (n=14; P=.002) at day 3 after wounding. Wound fluid collected on day 5 after wounding from cathepsin G-deficient mice attracted 58% more neutrophils than wound fluid collected from control mice (n=4; P<.05). CONCLUSIONS: Neutrophil cathepsin G is important during the early inflammatory stage of wound healing. Cathepsin G may be involved in processing 1 (or more) soluble mediator(s) in the wound milieu that is responsible for neutrophil chemotaxis. Our findings suggest that tight regulation of inflammation is necessary to prevent impaired healing during early tissue repair.