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Biomedical subjects

L A Hoffman

Publications and source records attributed to L A Hoffman.

At least 37 records · Page 2Linked to original sources
PubMed1997

Ischemia-reperfusion injury in myocutaneous flaps: role of leukocytes and leukotrienes.

Leukotriene B4 is a potent inflammatory mediator that is derived from the 5-lipoxygenase pathway of arachidonic acid metabolism and that has been implicated in the pathophysiology of polymorphonuclear leukocyte-dependent reperfusion injury in a variety of organ systems. The objectives of these investigations were to determine whether inhibition of leukotriene B4 attenuates postischemic polymorphonuclear leukocyte infiltration and subsequent injury in myocutaneous flaps. Anesthetized female Yorkshire pigs were randomized to receive normal saline (n = 8), the 5-lipoxygenase inhibitor diethylcarbamazine (n = 7), or the leukotriene B4 receptor antagonist SC-41930 (n = 7). All animals underwent 6 hours of rectus abdominis myocutaneous flap ischemia followed by 4 hours of reperfusion. In saline-treated controls, flap ischemia was associated with massive polymorphonuclear leukocyte infiltration at 1 and 4 hours of reperfusion (252 +/- 70 and 619 +/- 137 polymorphonuclear leukocytes per 25 high-power fields, respectively). Skeletal muscle neutrophil content was significantly attenuated by pretreatment with diethylcarbamazine (72 +/- 29 and 229 +/- 63 polymorphonuclear leukocytes per 25 high-power fields; p < 0.05) or SC-41930 (25 +/- 3 and 193 +/- 25 polymorphonuclear leukocytes per 25 high-power fields; p < 0.05). Wet-to-dry weight ratios of full-thickness flap biopsies were lower in the diethylcarbamazine and SC-41930 groups (2.98 +/- 0.15 and 2.90 +/- 0.26, respectively) than in the control group (4.13 +/- 0.23; p < 0.01), and mean muscle infarct size, as determined by nitroblue tetrazolium staining, diminished from 47.6 +/- 11.3 percent in controls to 25.1 +/- 6.5 percent in diethylcarbamazine-treated animals and 7.3 +/- 4.8 percent in SC41930-treated animals (p < 0.05). These data indicate that leukotriene B4 plays a critical role in mediating neutrophil-dependent injury in postischemic skeletal muscle flaps.

Animals↗
PubMed1997

Teaching COPD patients upper extremity exercises at home.

While exercise training for patients with COPD is time consuming and strenuous, we have seen through our experience that patients who comply with this simple and easy exercise program reported subjective improvement in ability to perform their activities of daily living. The key to exercise success is consistency and availability of reinforcement of techniques through the use of both written and in-person instruction.

Arm↗
PubMed1996

Modification of macrophage adhesion by ozone: role of cytokines and cell adhesion molecules.

The inflammatory response in the lungs following an inhalation exposure of animals and humans to ozone (O3) is associated with macrophage stimulation, release of chemotactic agents, and neutrophilia. This study investigated the adhesive behavior of the alveolar macrophages and its relevance to the inflammatory processes in the lung. Macrophages recovered by BAL from rats exposed to purified air or 0.8 ppm O3 were studied in vitro for their adhesion to epithelial cells derived from ARL-14. The macrophages from O3-exposed animals displayed greater adhesion to the epithelial cells than the macrophages from control rats exposed to purified air. The O3-induced adhesion was attenuated in the macrophages treated with a combination of interleukin-1 alpha and tumor necrosis factor-alpha antibodies (anti-IL-1+anti-TNF). The cell adhesion stimulated by O3 exposure was also attenuated when the macrophages were incubated in the presence of antibodies to leukocyte adhesion molecules, CD11b, or epithelial cell adhesion molecules, ICAM-1. A marginal increase in the surface expression of CD11b was noticed in macrophages from the rats exposed to O3. A similar change in the ICAM-1 expression was, however, not observed. The results suggest that the O3-induced modifications of macrophages are mediated by IL-1 and TNF, and that these modifications are accompanied by a minimal change in the expression of the cell-adhesion molecules.

Animals↗
PubMed1996

Craniofacial injuries resulting from taxicab accidents in New York City.

Taxicab accidents are a common occurrence in New York City. This review was undertaken to characterize the nature of craniofacial injuries that result from taxicab accidents. Data were collected on 16 patients who required admission to trauma or plastic and reconstructive surgery services, after sustaining craniofacial injury as a result of a taxicab accident. Front-end deceleration collisions were the most common mechanism of injury. Fifty-six percent of the patients were thrown against the bulletproof, Plexiglas driver safety divider and sustained an injury most commonly to the anterior midface. Both bony and soft-tissue injuries were common in the entire group. Complex facial fractures were sustained by 56% of patients, with nasal-septal fractures most common, followed by naso-ethmoid-orbital, anterior frontal, anterior maxillary, and Le Fort I and II fractures. Only 1 patient in the group was wearing a seat belt and that patient was a driver. Given the high incidence of craniofacial injury, appropriate safety standards for taxicabs must be initiated, including the reevaluation of the utility of the safety divider and mandatory seat belt use for rear-seat passengers.

Accidents, Traffic↗
PubMed1996

Terminal weaning from mechanical ventilation: planning and process.

There are two major goals of critical care: (1) to save those with a chance to live and (2) to help patients who are dying have a peaceful and dignified death. If reversal of the disease process is not possible and the patient is experiencing substantial pain and suffering, goals need to be reviewed and potentially redefined. These new goals may be to remove unwanted or nonbeneficial therapy, to provide death with dignity, and to support the family. This article details aspects of the decision-making process regarding withdrawal of mechanical ventilation, including ethical principles; decision-making for autonomous patients and non-autonomous patients; advance directives; planning withdrawal of support; terminal weaning methods; patient comfort; family support; and future directions for research, practice, and education.

Critical Care↗
PubMed1996

Economic cost of home-based care for ventilator-assisted individuals: a preliminary report.

STUDY OBJECTIVE: To measure the direct and indirect costs of maintaining a ventilator-assisted individual (VAI) at home. DESIGN: A cross-sectional survey was conducted of primary family caregivers of VAIs residing in 37 states. SETTING: Surveys were delivered to the homes of VAIs. PARTICIPANTS: Two hundred seventy-seven (19.7%) of 1,404 primary family caregivers of patients who were ventilator-dependent and who were living at home. Interventions. None. MEASURES: Participants received the modified Katz Index and an investigator-developed Home Ventilator Care Cost and Utilization Survey (HVCCUS). RESULTS: Total cost of care was determined by summing total direct medical and nonmedical costs of home care and lost wages. Using LPN rates for private duty care, the average total cost of care was estimated to be $7,642 per month (median=$5,406). Using RN rates for private duty care, the average total cost of home care was estimated to be $8,596 per month (median=$5,911). Variation with VAI characteristics is discussed. CONCLUSIONS: Home care of VAIs is a labor-intensive and an economically costly undertaking. The development of policies and programs to support home placement requires additional investigation regarding factors affecting the cost-effectiveness of various placement settings, as well as the ability and/or willingness of family members to accept the cost and responsibility of home care.

Adult↗
PubMed1995

Squamous cell carcinoma of the breast after augmentation with liquid silicone injection.

Squamous cell carcinoma of the breast is an extremely rare neoplasm. Approximately 50 cases have been reported in the English literature since 1917. The pathogenesis of squamous cell carcinoma of the breast is puzzling because epithelial elements are not normally identified in breast tissue. It has been suggested that epithelial cells are derived from epidermoid cysts deposited during early embryological development, from metaplastic transformation of ductal cells, or after trauma or surgical manipulation. Although no evidence has been published to support a casual relationship between liquid silicone-induced mastopathy and breast carcinoma, squamous cell cancers are known to arise in the setting of prolonged inflammation often seen after liquid silicone injection. This case of primary squamous cell carcinoma of the breast, arising 25 years after augmentation with liquid silicone injections, occurred in a 70-year-old patient with silicone-induced mastopathy.

Aged↗
PubMed1995

Neutrophil lipoxygenase activation and leukosequestration in postischemic myocutaneous flaps: role of LTB4.

Reperfusion of ischemic tissues leads to eicosanoid- and polymorphonuclear leukocyte (PMN)-dependent injury. The present experiments were undertaken to examine the effect of myocutaneous flap ischemia-reperfusion on neutrophil 5-lipoxygenase activity and to define the role of leukotriene B4 (LTB4) in postischemic PMN infiltration into such composite tissue grafts. Anesthetized Yorkshire pigs underwent 6 h of rectus abdominis myocutaneous flap ischemia or sham ischemia, and LTB4 generation was measured in calcium ionophore-stimulated neutrophils isolated from the circulation. At 30 min of reperfusion, neutrophil generation of LTB4 increased from a baseline value of 31.0 +/- 6.8 to 98.5 +/- 5.1 ng/5 x 10(6) PMN (P < 0.01) and was significantly greater than those neutrophils isolated from animals subjected to sham ischemia and reperfusion (54.3 +/- 4.1 ng/5 x 10(6) PMN; P < 0.01). Pretreatment of animals with the LTB4-receptor antagonist, SC-41930 (n = 5), significantly attenuated reperfusion-associated 5-lipoxygenase activation (60.3 +/- 11.6 ng LTB4/5 x 10(6) PMN; P < 0.01), suggesting the presence of a positive feedback mechanism for eicosanoid biosynthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Ultraviolet excitation fluorescence spectroscopy: a noninvasive method for the measurement of redox changes in ischemic myocutaneous flaps.

In this report, we discuss application of the noninvasive technology of ultraviolet fluorescence spectroscopy to the metabolic analysis of normal and compromised myocutaneous flaps. Acute changes in tissue redox states during ischemia and reperfusion were determined analysis of changes in the fluorescence spectrum of reduced nicotinomide adenine dinucleotide (NADH). Analysis of the system for NADH fluorescence showed good correlation between excitation spectra recorded at 450 nm from pure beta-NADH and those recorded from porcine rectus abdominis myocutaneous flaps. Sequential measurements of surface fluorescence were obtained from six flaps subjected to 6 hours of warm arterial ischemia and 4 hours of reperfusion. Results were compared with spectra obtained from six contralateral nonischemic control flaps. A significant mean increase in NADH fluorescence (49 percent; p < 0.05) was demonstrated within 30 minutes of vascular occlusion. Fluorescence intensity continued to increase throughout the ischemic period, reaching 320.5 percent of baseline values at 6 hours. Reperfusion resulted in the prompt return of fluorescence intensity to baseline levels. These results show that fluorescence spectroscopy of endogenous NADH is a sensitive and reliable indicator of vascular occlusion in experimental myocutaneous flaps.

Animals↗
PubMed1995

Acute care nurse practitioner curriculum: content and development process.

Curriculum development for preparation of acute care nurse practitioners requires a comprehensive process. To develop a program for their preparation at a large university, the faculty examined needs of the target patient population and care delivery system; scope of acute care nurse practitioner practice; current guidelines for the education of primary care nurse practitioners; evolving guidelines for the didactic and clinical education of acute care nurse practitioners; educational requirements of governing or licensing and certifying bodies; and placement of this new role within the existing healthcare team structure. A curriculum was then developed using a collaborative, multidisciplinary approach.

Acute Disease↗
PubMed1995

Bone marrow-derived chimerism in non-irradiated, cyclosporin-treated rats receiving microvascularized limb transplants: evidence for donor-derived dendritic cells in recipient lymphoid tissues.

Tolerance to donor transplantation antigens develops when recipients are made chimeric with donor bone marrow. To establish chimerism, the haemopoietic system of recipients typically is severely compromised. We report on a system in which chimerism develops without ablative therapies. Immunosuppression with cyclosporin A allowed the lower limb of a rat to be replaced by a microvascularized transplant from a fully allogeneic donor. Many donor-derived cells populated recipient lymph nodes and spleen, and most had the large size, irregular shape and strong major histocompatibility complex (MHC) class II expression that typify dendritic cells. Donor cells were not found in the macrophage-rich regions of lymphoid tissues, but instead occupied splenic white pulp and lymph node cortex. The donor cells were derived from radiosensitive marrow precursors, as chimerism was abolished if the grafted limb was irradiated, or if muscle and skin flaps devoid of bone were grafted. Donor cells were rare or not detectable in blood, thymus and liver. Whereas lymphoid chimerism was prominent following limb transfer, donor cells were not detected 1-2 weeks after an injection of two femur equivalents of a marrow suspension. We suggest that dendritic cells that undergo rapid turnover in lymphoid organs are replaced from allogeneic precursors in bone grafts. The combination of cyclosporin and vascularized bone provides a means for inducing chimerism in lymphoid tissues of non-irradiated recipients.

Animals↗
PubMed1994

Surgical management of syndactyly in a dog.

This report describes the treatment of simple syndactyly in a Golden Retriever. The left forepaw lacked cutaneous separation between the digits and had confluent metacarpal and digital pads. After vigorous exercise, the dog had intermittent non-weight-bearing lameness involving the affected forepaw. The lameness may have resulted from stretching of the thin skin on the dorsum of the paw as the digits attempted to spread during weight bearing. Surgical separation of digits 3 and 4 was performed by creating an interdigital web space with dorsal and palmar skin flaps and by covering the exposed axial surfaces with full-thickness skin grafts. At 11 weeks after surgery, the lameness had improved and the dog's level of activity had increased.

Animals↗
PubMed1994

An old friendship revisited: plastic surgery and transplantation.

Plastic surgery has a rich history in the development of the field of transplantation. Many prominent plastic surgeons, while undertaking experimental as well as clinical efforts, pioneered and assisted in the establishment of journals and societies devoted exclusively to the field of transplantation. Much of this work was initiated during World War II, a time when transplantation was viewed with suspicion by both scientists and clinicians. While work in this area has undergone a quiescence among members of our specialty, advances in microsurgery and immunology have rekindled interest among plastic surgeons.

History, 20th Century↗
PubMed1994

Silicone migration to the pleural space associated with silicone-gel augmentation mammaplasty.

We present a case report of silicone particles found in the pleural fluid of a patient 20 years after bilateral augmentation mammaplasty with silicone-gel implants. The patient's history is notable for bilateral replacements of implants and multiple closed capsulotomies several years subsequent to the original augmentation procedure. A ruptured left implant was found in 1991 when she first experienced pain in the upper back. A left pleural effusion developed subsequently. Analysis of the pleural effusion fluid by scanning electron microscopy suggested the presence of silicone. All laboratory results were normal, and the effusion did not recur after thoracentesis. The patient has been under close follow-up, and further pulmonary complications or other symptoms have not developed. This case report demonstrates the potential for silicone migration to the pleura and the possibility of subsequent pulmonary complications, such as pleural effusion.

Female↗
PubMed1994

The use of Mitek anchors to secure mesh in abdominal wall reconstruction.

Abdominal wall complications of TRAM flap breast reconstruction are well described. Synthetic mesh abdominal reinforcement is believed to decrease the incidence of these complications. An innovative technique with commonly available suture anchors has been used in a case of recurrent abdominal laxity after a TRAM flap. Osseous fixation of synthetic mesh with the Mitek GII suture anchor will undoubtedly be used more widely in abdominal wall reconstruction.

Abdominal Muscles↗
PubMed1994

Midline defects of the orofaciodigital syndrome type VI (Váradi syndrome).

The orofaciodigital syndromes (OFDS) represent a spectrum of anomalies of the palate, cranium, hands, and feet. Váradi syndrome, designated OFDS type VI, is a rare disorder that is additionally characterized by cerebellar anomalies. The following report is of a patient with OFDS VI and characteristic multiple midline defects: median cleft lip and palate, lingual cleft with nodules, and midline brain malformation. In addition, this case is uniquely associated with the presence of midline (metopic and sagittal) craniosynostoses as well. It is unusual that deformities which result from premature fusion of cranial vault sutures would appear synchronously in a syndrome based on the concept of failure of fusion or coalescence of facial growth centers. The midline represents an independent developmental field, whereby CNS defects and midline anomalies can present concurrently.

Cerebellum↗
PubMed1994

Novel strategies for delivering oxygen: reservoir cannula, demand flow, and transtracheal oxygen administration.

Oxygen-conserving devices can decrease costs because less oxygen is used. However, they may also add costs due to the more complex equipment involved (ie, device and catheter replacement). Oxygen is relatively expensive. To decrease the cost of oxygen therapy, conserving devices must decrease the frequency of home deliveries and/or the number of cylinders used. By promoting mobility and improving adherence to continuous oxygen therapy, oxygen-conserving systems may increase the amount of oxygen used, thus offsetting savings. It is shortsighted to focus only on reducing the costs of oxygen administration. Attention also needs to be directed to patient outcomes such as functional status, use of healthcare services, and quality of life.

Costs and Cost Analysis↗