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Biomedical subjects

S R Baker

Publications and source records attributed to S R Baker.

At least 91 records · Page 5Linked to original sources
PubMed1991

Mandible reconstruction with vascularized bone grafts. A histologic evaluation.

To our knowledge, a histologic evaluation of bone healing after mandible reconstruction with vascularized human bone grafts has not been previously reported. Serial sections through both the decalcified graft and the junction between mandible and graft were evaluated in four patients who required surgical removal of their reconstructed mandibles. A failed scapular bone graft that had been wrapped within a pectoralis major myocutaneous flap for salvage following pedicle thrombosis showed markedly resorbed but viable bone with a fibrous union to the native mandible. Viable vascularized grafts without evidence of ongoing resorption characterized an iliac osteocutaneous bone graft and two scapula osteocutaneous grafts that healed with continuity of healthy bone between graft and mandible. Observations from the evaluation of these specimens are made regarding bone circulation, bone union, and bone graft survival as they occur clinically. Implications regarding the techniques of bone plating and indications for use of vascularized bone in mandible reconstruction are discussed.

Bone Transplantation↗
PubMed1991

Epidemiology of chronic venous ulcers.

A metropolitan population of 238,000 in Perth, Western Australia, was screened for chronic ulceration of the leg. Patients with a chronic leg ulcer and a venous abnormality comprised 57 per cent of all patients with a chronic leg ulcer, giving a prevalence of 0.62 per 1000 population. There was an increasing prevalence with age; 90 per cent of patients were 60 years and older. This group comprised 16.7 per cent of the population, and had a prevalence of 3.3 per 1000. Although chronic venous ulcers were more common in women there was no difference in age related prevalence. In 36 per cent of patients with a venous abnormality, there was at least one other aetiological factor contributing to chronic ulceration of the leg; 96 per cent had either a history of deep venous thrombosis or a condition known to predispose to deep venous thrombosis.

Adult↗
PubMed1991

Outpatient treatment of chronic venous ulcers in a specialized clinic.

Chronic leg ulcers have many different causes and therefore need an accurate diagnosis in order to give the most effective treatment. A specialized clinic was set up in Fremantle Hospital in July 1988 with the aims of performing a thorough clinical and laboratory assessment to establish the cause of ulceration in every patient, and treating patients according to the cause of ulceration. Patients with arterial, neoplastic or dermatological conditions were treated as appropriate for their diagnosis and patients with other chronic ulcers were managed as outpatients where possible. Patients were seen between July 1988 and July 1989. Only 43% had purely venous ulcers, 32.6% had a venous component plus some other abnormality, and 5.2% were purely arterial. Using an outpatient treatment regimen, 67% of all ulcerated limbs and 73.7% of limbs with purely venous ulcers were healed within 6 months. Only 11 patients with venous ulceration (15 limbs) failed on this therapy and required admission during the observation period. The initial ulcer size was shown to influence the time to total healing of the limb. The healing rates achieved compare favourably with studies from other specialized centres and suggest that the majority of patients with chronic leg ulcers can be treated successfully using ambulatory outpatient dressing techniques.

Adult↗
PubMed1991

Air in the fissure for the ligamentum teres: new sign of intraperitoneal air on plain radiographs.

In each of four patients in whom an acute spontaneous pneumoperitoneum developed, a vertically directed area of hyperlucency in the right upper quadrant was seen on radiographs of the abdomen obtained with the patient supine. This finding, which appeared in the absence of other characteristic signs of free air on plain radiographs and which, to the authors' knowledge, has not been previously recognized, represented intraperitoneal gas confined to the fissure for the ligamentum teres (FLT). The location of the hyperlucent area was confirmed with computed tomography or laparotomy in each patient. The distinctive configuration of air in the FLT is a subtle but reliable indicator of pneumoperitoneum.

Aged↗
PubMed1991

Leukotriene receptor on U-937 cells: discriminatory responses to leukotrienes C4 and D4.

Dimethyl sulfoxide (DMSO)-differentiated U-937 cells develop cell surface receptors for leukotrienes that, when stimulated, initiate a transient increase in intracellular calcium concentration [( Ca2+]i). We investigated the calcium transient that occurs after addition of leukotriene C4 (LTC4) to determine whether it occurs due to 1) the bioconversion of LTC4 to leukotriene D4 (LTD4), which then acts at the LTD4 receptor; 2) the direct action of LTC4 at the LTD4 receptor; or 3) the action of LTC4 at a receptor selective for LTC4. Bioconversion of [3H]LTC4 to [3H]LTD4 was inhibited by 98% when DMSO-differentiated U-937 cells were incubated with 10 mM AT-125 compared with control cells. The dose-response curve for LTC4, with [Ca2+]i as the index of response, was parallel to that for LTD4 but was significantly (P less than 0.0001) shifted 1.6 +/- 0.11 log units to the right. AT-125 did not change the response to LTD4 but the LTC4 dose-response curve was shifted on additional 1.7 logo units to the right. The antagonists SKF 104353 (1 microM) and LY 171883 (10 microM) shifted the dose-response curve for LTD4 3.0 +/- 0.23 and 2.5 +/- 0.23 log units, respectively, to the right and completely inhibited the change in [Ca2+]i due to LTC4 in the presence of 10 mM AT-125. Molecular modeling studies demonstrated a striking difference in the spatial configuration of LTC4 and LTD4, likely accounting for the ability of cell surface receptors to discriminate between the effects of these two molecules.(ABSTRACT TRUNCATED AT 250 WORDS)

Biotransformation↗
PubMed1990

Utility of emission tomography in evaluation of mandibular bone grafts.

Bone scanning, performed within 1 week postoperatively, is valuable in predicting the survival of revascularized composite flap grafts. Conventional planar scintigraphy is limited by a two-dimensional representation of three-dimensional structures. Single photon emission computed tomography (SPECT) is a technique in which a gamma camera rotates around the patient, acquires multiple projections, and with the aid of a computer, reconstructs three-dimensional representations. We wished to evaluate the potential advantages of SPECT in the assessment of mandibular graft viability and to compare it with planar scanning. These noninvasive methods of assessing the vascular supply are critical to patient management in the early postoperative period because the presence of or inability to exclude vascular compromise commands surgical exploration of the anastomosis for graft salvage. Fifteen patients who underwent mandibular reconstruction with revascularized free grafts were studied by both planar and SPECT scintigraphy. Long-term follow-up data were correlated with the outcome predicted by the scanning.

Adult↗
PubMed1990

The cutaneous scapular free flap in head and neck reconstruction.

Successful surgical reconstruction of complicated soft-tissue defects of the head and neck region has been greatly enhanced by free-revascularized tissue transfers. The scapular free flap has become a favored reconstructive option in our department and has been reported previously for one-stage mandibular reconstruction. This flap can also be transferred as a cutaneous free flap. We present our clinical experience with the fasciocutaneous scapular free flap and review the anatomy, surgical technique, and utility of this versatile flap.

Adult↗
PubMed1990

Tracheostoma diverticulum following tracheoesophageal puncture.

Although the initial reports of tracheoesophageal puncture after total laryngectomy reported little to no morbidity, subsequent studies with longer follow-up have reported a significant number of complications. We present the first reported case (to our knowledge) of prolapse of the posterior tracheal wall with diverticulum formation developing 6 years after continuous use of tracheoesophageal puncture speech. Preoperative assessment with a barium esophagogram and rigid esophagoscopy aided in the successful surgical treatment of this disorder. The pathogenesis of this complication and method of repair are discussed.

Diverticulum↗
PubMed1990

Tissue expansion of the head and neck. Indications, technique, and complications.

Tissue expansion is indicated in the reconstruction of various defects of the head and neck in instances where there is inadequate adjacent tissue to allow either primary closure of the defect or repair with a local flap. It may also be indicated in instances where repair of a defect by an alternative method such as a local, regional, or distant flap will result in an unacceptable donor or recipient site deformity. Although tissue expansion is simplistic in concept, it does require judgment and indepth preoperative planning to ensure optimal results. The complication rate is high for tissue expansion in the head and neck, particularly in the cheek and neck area. Despite the frequency of complications, in the vast majority of cases the intended reconstruction is successful.

Dermatologic Surgical Procedures↗
PubMed1990

Rapid intraoperative tissue expansion in reconstruction of the head and neck.

A prolonged tissue expansion has the advantage of creating large amounts of additional skin for reconstructing cutaneous defects that might not be possible without the use of multiple, regional, distant, or microsurgical flaps. In spite of this, there are disadvantages, many of which can be circumvented by the use of rapid intraoperative tissue expansion instead. Although rapid expansion does not increase skin surface area as much as prolonged expansion, it may be helpful in assisting with closure of defects that might otherwise be problematic.

Face↗
PubMed1990

The pharmacology of N-methyl LTC4; a metabolically stable LTC4-mimetic.

N-methyl LTC4 (NMLTC4) a synthetic analogue of LTC4, has been shown not to be a substrate for gamma-glutamyl transpeptidase. NMLTC4 produced contractions of the guinea pig ileum and trachea with pD2 values of 7.7 +/- 0.12 (n = 6) and 8.1 +/- 0.1 (n = 6) respectively, compared with values of 9.0 +/- 0.1 (n = 5) and 8.0 +/- 0.2 (n = 6) for LTC4. The concentration-response curve to LTC4 and NMLTC4 on ileum was displaced to the right by FPL55712. The corresponding pA2 values were 6.3 +/- 0.3 (n = 10) for LTC4 and 5.7 +/- 0.2 (n = 6) for NMLTC4. In the presence of acivicin, a gamma-glutamyl transpeptidase inhibitor, the LTC4 concentration-response curve on trachea was displaced to the left, but the NMLTC4 curve was unaffected. The comparative potencies in the presence of acivicin on trachea indicate that LTC4 is approximately 6 times more potent than NMLTC4 whereas on ileum, in the presence of FPL55712 LTC4 is approximately 14 times more potent. In-vivo NMLTC4 is a weak bronchoconstrictor substance being 20-30 less potent than LTC4. However, unlike the in-vitro studies the bronchospasm was significantly reduced by pretreatment with LTD4 antagonists. NMLTC4 administered intravenously produced a pronounced hypertensive effect which appeared to be due to peripheral vasoconstriction.

Animals↗
PubMed1990

Squamous carcinoma of the head and neck in organ transplant recipients: possible role of oncogenic viruses.

A consistently increased incidence of malignancies in renal transplant recipients has been attributed to the effect of chronic immunosuppression required to prevent transplant rejection. Tumors arising in such patients offer a unique opportunity to study the interactions of the immune system and tumor development. A series of three cases of head and neck squamous cell carcinoma arising in patients after renal, cardiac, or bone marrow transplantation are reported. Patient ages at tumor diagnosis were 18, 29, and 53 years, respectively. Time from transplant to diagnosis of tumor ranged from 7 months to 12 years. Only the youngest patient lacked a history of exposure to the traditional pre-disposing factors of tobacco and alcohol use. Histopathologic examination in all three tumors showed features of koilocytosis with hyperkeratosis and parakeratosis suggestive of papillomavirus infection. Squamous carcinoma cells from one of these patients have been successfully established in cell culture. Immune system impairments secondary to the use of antirejection drugs could allow the expression of oncogenic viruses. A recent report of human papillomavirus (HPV) DNA in a primary and metastatic perianal squamous cell carcinoma from a renal transplant recipient, as well as the reported presence of HPV in benign and malignant neoplasms of the upper aerodigestive tract suggests that HPV infection could play a role in the development of squamous carcinomas in transplant recipients. Further studies of HPV infection in cultured cell lines derived from head and neck tumors occurring in immunosuppressed patients are needed to define this relationship.

Adolescent↗
PubMed1990

Clinical applications of tissue expansion in head and neck surgery.

Tissue expansion offers a new frontier in head and neck reconstruction in that it provides the capability of creating additional new skin for restoration of defects with skin of identical color, thickness, and appendages. The applicability of tissue expansion is only beginning to be appreciated as it is used in various aspects of head and neck surgery. Currently, the technique is most frequently used in scalp surgery for correction of male pattern baldness. Other uses of tissue expansion are in cranial facial surgery and expansion of distant, regional, or microsurgical flaps. Perhaps its greatest value from a reconstructive perspective, however, is in providing new skin for reconstruction of various facial defects through the use of primary wound closure or a multitude of local flaps.

Cheek↗
PubMed1990

Local control of auricular, periauricular, and external canal cutaneous malignancies with Mohs surgery.

Three hundred ninety-seven patients with 407 cutaneous malignancies of the auricle, periauricular region, and cartilaginous external ear canal were reviewed. Tumors were most commonly located in the preauricular and postauricular regions, followed by the helix, concha, antihelix, and ear canal. All lesions were excised with Mohs microscopic control of margins. For lesions requiring lateral temporal bone resection, an adaptation of fresh-tissue microscopic control was used to analyze deep and anterior margins suspected of harboring residual tumor. Two-year minimum follow-up of 229 patients with periauricular and auricular tumors (N = 231 tumors) and 14 patients with cartilaginous ear canal tumors (N = 14 tumors) revealed recurrence rates of 6.9% and 14.3%, respectively. Recurrences were most common in cases of large tumors (greater than 2.5 cm), basal cell carcinomas with morphea elements, and multiply recurrent lesions. We conclude that Mohs surgery is comparatively effective, though not uniformly curative, and can be adapted to supplement excision of large tumors in these regions.

Basal Cell Carcinoma↗
PubMed1990

Chondrosarcoma of the head and neck.

Chondrosarcoma is a malignancy rarely encountered in the head and neck. In an attempt to define this tumor's characteristics and response to therapy, all cases of chondrosarcoma treated at the University of Michigan over the past 25 years were retrospectively studied. Fourteen cases originating in the nose and paranasal sinuses, mandible, temporal bone, and larynx were reviewed. Aggressive surgical resection was the mainstay of treatment, and resulted in an overall survival of 70%, with an average follow-up of 3.5 years. Survival was highest in primary temporal bone lesions, and lowest in paranasal sinus lesions. Unresectable lesions were not cured by other modalities. This study, therefore, continued to support the crucial role of wide surgical resection in the treatment of head and neck chondrosarcoma, but conservative resection, when needed to preserve important structures, has resulted in long-term survival.

Adolescent↗
PubMed1990

Use of a metal detector to identify ingested metallic foreign bodies.

A metal detector reveals the presence of metallic objects by measuring the change in the inductance of a coil placed near a metallic mass. The device used in this study is similar in principle to those used for passenger surveillance in airports except for its smaller size and simpler design. In this study, we compared the accuracy of a metal detector with that of plain radiographs for the localization of ingested metallic objects. Twenty-eight consecutive patients with the presumptive diagnosis of metallic foreign-body ingestion were examined with a metal detector. The results were compared with those of plain radiographs which were considered the gold standard. Fifteen positive cases and 13 negative cases were correctly diagnosed by metal detector examination. No false-positive or false-negative results occurred. Our experience suggests that metal detection is a simple and accurate technique for the localization of ingested metallic objects and provides information equivalent to that from plain radiographs for the treatment of patients with suspected foreign-body ingestion.

Adult↗
PubMed1990

Current management of cancer of the lip.

Carcinoma of the lip is the most common cancer of the oral cavity, occurring most frequently on the lower lip of elderly males. Less advanced neoplasms may be treated equally successfully by surgery or irradiation, and results are cosmetically acceptable by both methods. Reconstruction of the lip following surgical ablation of tumor usually consists of primary repair. Larger defects require flaps from the opposite lip, adjacent cheek, or more distant tissue. Although prophylactic neck dissection is usually not indicated, the presence of neck metastases from carcinoma of the lip is best managed by neck dissection followed by postoperative radiotherapy. The prognosis for curing lip cancer is dependent upon the size of the primary tumor and whether cervical metastasis has occurred. The overall five-year cure rate of lip cancer approximates 80%. The cure rate of patients with neck metastases is approximately 50%.

Carcinoma↗