PubMed Health⌕ Search

Biomedical subjects

A Orenstein

Publications and source records attributed to A Orenstein.

At least 55 records · Page 3Linked to original sources
PubMed1988

Mechanism of tumor destruction following photodynamic therapy with hematoporphyrin derivative, chlorin, and phthalocyanine.

The effect of photodynamic therapy on the tumor microvasculature in the first few hours after treatment was studied at the light and electron microscopy levels. BALB/c mice with EMT-6 tumor received ip injections of hematoporphyrin derivative, chlorin, or phthalocyanine, and 24 hours later, the tumors were treated with light at 100 J/cm2 at the appropriate therapeutic wavelength for each photosensitizer. Animals were killed and their tumors removed at time 0, 30 minutes, 1 hour, and 2, 4, 6, 8, 12, 16, and 24 hours after treatment. The results indicate that for all three sensitizers the effects of photodynamic therapy leading to rapid necrosis of tumor tissue are not the result of direct tumor cell kill but are secondary to destruction of the tumor microvasculature. The first observable signs of destruction occur in the subendothelial zone of the tumor capillary wall. This zone, composed of dense collagen fibers and other connective tissue elements, is destroyed in the first few hours after phototherapy. However, the ultrastructural changes seen in this zone are different for the hematoporphyrin derivative, compared with chlorin and phthalocyanine. Binding of photosensitizers to the elements in this zone as well as altered permeability and transport through the endothelial cell layer because of the increased intraluminal pressure may be key features of tumor destruction.

Animals↗
PubMed1988

Ablation of bone and methacrylate by a prototype mid-infrared erbium:YAG laser.

An erbium:YAG laser was used to generate 200-microseconds pulses of mid-infrared 2.94-microns light in both the single and multimode configurations. Laser pulses were focused on the surfaces of both rabbit long bones and methacrylate blocks, and the tissue response was examined histologically. The depth of thermal injury was determined by ocular micrometry. Over all energy levels tested, the erbium:YAG laser produced ablation of bone and methacrylate with minimal thermal damage to adjacent tissue. Increasing the laser energy per pulse produced increasingly wider and deeper grooves in both bone and methacrylate. However, such increase in laser energy produced a proportionately greater increase in the zone of thermal injury in methacrylate as compared with bone. These studies suggest the feasibility of a surgical erbium:YAG laser in orthopaedics and other forms of ablative surgery.

Animals↗
PubMed1988

Mapping of the human body skin with the transcutaneous oxygen pressure method.

Transcutaneous oxygen pressure (TcPO2) measurements are studied to determine whether location, side of body, sex, and age affect the values at 23 different sites. Measurements were taken on 19 healthy volunteers on one side or the other of the body. Values were similar at all sites with the exception of the forehead, cheek, medial aspect of the leg, and the scapular region. There was no difference between sides of the body or between younger and older subjects. Women had significantly higher values. The results are discussed, and it is concluded that most skin regions can serve as controls for areas under investigation.

Adult↗
PubMed1988

Immunofluorescent localization of cytokeratin intermediate filaments as a means of defining the presence of recurrent basal cell carcinoma.

Intermediate filament subunits are reliable markers of cytogenetic origin for both normal and neoplastic cells. Immunohistochemical localization of cytokeratin filaments offers a sensitive and specific means of identifying basal or reserve cells when studying histologic sections of skin biopsy specimens. We have applied this technique on eighteen cases in which unequivocal diagnosis or recurrent basal cell carcinoma could not be rendered by conventional histologic techniques. In three of the cases studied, microscopic islands of basal cell carcinoma could be demonstrated by positive staining with cytokeratin antibodies. In the remaining fifteen cases, the possibility of recurrent basal cell carcinoma could be conclusively eliminated on the basis of negative staining with this antibody. Immunolabeling with tissue specific cytokeratin antibodies by indirect immunofluorescent examination may thus constitute a reliable and relatively simple technique that may serve to establish a definitive diagnosis in equivocal cases of suspected recurrent basal cell carcinoma.

Biomarkers, Tumor↗
PubMed1988

Adaptive and reactive distancing among adolescents from alcoholic families.

Based on work with adolescents at a mental health center and an alcohol education program, some of the difficulties children of alcoholics experience in separating from their homes are considered. These difficulties are described in terms of organizing fantasies in which adolescents use relationships outside of their homes to work through unresolved feelings about their families.

Adaptation, Psychological↗
PubMed1987

Factitious lymphedema of the hand: a diagnostic challenge.

A case of factitious lymphedema of the hand is presented. Attention is drawn to this entity and its differential diagnosis. Delayed detection in our case resulted in prolonged and costly hospitalization with some loss of hand function. Treatment should be left to those skilled in psychotherapy.

Adult↗
PubMed1986

Pseudomelanoma following laser therapy for congenital nevus.

Benign nevi can be removed by a variety of procedures including surgical excision, electrocautery, slicing off the protruding portion by a shave biopsy, cryotherapy, dermabrasion, etc. Except in the case of complete excision, these procedures may often be followed by recurrence. We describe a congenital nevus that was incompletely removed by CO2 laser therapy. When the lesion recurred, it had clinical as well as histologic features in common with malignant melanoma, although it was completely benign.

Dermatologic Surgical Procedures↗
PubMed1984

Evaluation of the CASPAR alcohol education curriculum.

The CASPAR education-prevention program was initiated when experimental results indicated that a 5-hr alcohol education curriculum at a Catholic high school was able to reduce frequent intoxication among teenagers. Attempts to institutionalize such a program in the public schools shows that (1) alcohol education can generate widespread community and school support; (2) workshops can successfully train teachers to adopt a decision-making approach, though close supervision is needed to ensure that this approach is adhered to in classroom teaching; (3) the CASPAR model of alcohol education produces classroom situations conducive to many children feeling free to express alcohol-related concerns; (4) trained teachers can serve as intermediaries between students with alcohol-related concerns and community resources, in particular those resources that are designed to help children from families with alcoholism; (5) the CASPAR curriculum, implemented by trained teachers, produces statistically significant knowledge and attitude gains, whereas alternate programs such as a special-events approach produce smaller knowledge gains and little attitude change; and (6) to a considerable extent, knowledge and attitude gains persist over time, although retention is greater on knowledge items and among older students. The results suggest that there may be a behavioral impact of instruction in the form of reduced alcohol misuse among teenagers, although if there is, it requires intensive and repeated exposure and can be demonstrated in these data only among younger students while they remain in junior high school. Although such results may be viewed as less supportive than the original experiment with which this work began, they do suggest that alcohol education remains an effective prevention strategy.

Adolescent↗
PubMed1983

The effect of ischemia of the dog's colon on transmural migration of bacteria and endotoxin.

The purpose of this investigation was to evaluate the effect of temporary ischemia created during the surgical preparation of the colon for resection on transmural migration of bacteria and passage of endotoxin through the ischemic wall of the canine colon. Eighteen dogs were used: in fourteen the colon was devascularized by ligating all marginal vessels. Aerobic and anaerobic cultures and washings for endotoxin assay were obtained from the surface of the bowel at intervals up to 6 hr after creating the ischemia. Peripheral and portal blood samples were also obtained at equal intervals for bacteriologic cultures and endotoxin assay. Bacterial transmural migration was examined in 10 dogs. In 6 of the dogs biologically marked bacteria were introduced into the colon via a rectal catheter before producing the ischemia. In 4 dogs radioactively labeled endotoxin was introduced into the colon in a similar fashion. In all the dogs, surface cultures, both routine and specific for the marked bacteria, were negative for the whole period of up to 6 hr after creation of ischemia. All portal and peripheral vein cultures were also negative. Transmural migration of endotoxin was investigated in 8 dogs, 4 of which served as controls and underwent a sham operation. In the 4 dogs in which the colon was devascularized endotoxin was discovered in peritoneal washings, and in portal and systemic blood samples, as early as 30 min after the preparation of the bowel was completed. In the control dogs endotoxin assays were negative throughout the experiment. In this model up to 6 hr of ischemia did not result in migration of bacteria through the ischemic wall. Endotoxin, however, entered the peritoneum and the blood very soon after producing the ischemia.

Animals↗
PubMed1983

Hair-bearing neck flap for upper-lip reconstruction in the male.

Reconstruction of the upper lip resulting in a hair-bearing area and a non-hair-bearing lining is described in two cases of full-thickness lip defects. A unipedicled neck flap was used in one case and a bipedicled neck flap in the other, both comprised of hair-bearing and adjacent non-hair-bearing areas. The neck flap has the advantages of providing the two layers of the lip, and the reconstructed lip is not too thick and is mobile and pliable, and the hair resembles lip hair in color, density, and quality. The multiple operative procedures can be performed under local anesthetic.

Adult↗
PubMedDate not supplied

The effect of reduction of the peripheral fat content by liposuction-assisted lipectomy (SAL) on serum leptin levels in the postoperative period: a prospective study.

The purpose of this study was to investigate the relationship between a decrease in the peripheral fat content by suction-assisted lipectomy (SAL) and serum leptin levels. Twenty-two healthy females who underwent SAL for aesthetic reasons participated in the study. The data included height, weight, dietary habits, and leptin levels before surgery and at 1 and 6 weeks postoperatively. The aspirate ranged between 1000 and 6000 ml, with an average of 2700 ml. Thirteen patients with an aspirate of over 2700 ml all experienced an immediate postoperative decrease in appetite which returned gradually by 12 to 17 days postoperatively. They lost an average of 7% of the total body weight at 6 weeks. The leptin levels 1 week postoperatively were significantly lower than the preoperative levels (p < 0.01); at 6 weeks the decrease in leptin level was not statistically significant. In conclusion, a reduction of the peripheral fat content of more than 2700 ml by SAL has an immediate effect on leptin levels that lasts at least 1 week and correlates with voluntary changes in energy intake.

Adult↗