Search PubMed⌕ Search

Biomedical subjects

W T Lawrence

Publications and source records attributed to W T Lawrence.

At least 55 records · Page 3Linked to original sources
PubMed1987

Wound healing in sarcoma-bearing rats: tumor effects on cutaneous and deep wounds.

Many surgeons think that cancer causes a higher incidence of wound complications. Wound healing was examined in a cutaneous and deep model in control and sarcoma-bearing rats to evaluate this concept. In a dorsal incisional wound, a significant decrease in wound breaking strength was observed from 19 days after tumor implantation onward. The amount of the breaking strength deficit increased with the size of tumor and the day post-tumor implant. In a deeper wound chamber, hydroxyproline levels, 3H-thymidine incorporation into DNA, histology, and collagen types were examined, and tumor produced no significant change in any parameter. The presence of tumor appeared to inhibit wound healing in cutaneous wounds but had no apparent effect on deeper wounds. This difference in healing in the two wound models is important to surgical oncologists. Because there is no demonstrable tumor-induced healing deficit in deep wounds, cancer-bearing organisms probably still heal these wounds normally.

Animals↗
PubMed1987

Ureteric stone surgery in practice.

From 1983 to 1986 140 patients underwent surgery for ureteric calculus. In approximately 30% "blind" basket extraction was considered appropriate and continued to be effective. Increasing expertise with the rigid ureterorenoscope led to a considerable reduction in open ureterolithotomy (15% in 1985-86), the majority following failed ureteroscopic extraction. In the same year both "blind" basket extraction and ureteroscopy were successful in 82 and 86% of attempts respectively. Electrohydraulic and ultrasonic lithotripsy were used in 12 patients to reduce large impacted calculi. The commonest complication of ureteroscopic stone surgery was perforation; this occurred in 14% of cases, though it was usually trivial and near the vesicoureteric junction. Perforations higher in the ureter tended to follow endoscopic lithotripsy and were often associated with urinary extravasation. Extra-ureteric stone fragments were also occasionally observed in such cases. There were no serious sequelae, although the in-patient stay was prolonged beyond the 48 h customary for uncomplicated extraction. The results suggest that ureteroscopic stone extraction, which can be conveniently introduced into urological practice, should become a standard endoscopic procedure.

Endoscopy↗
PubMed1986

The tolerance of skin grafts to postoperative radiation therapy in patients with soft-tissue sarcoma.

During the last ten years at the National Cancer Institute, 11 patients have received 12 courses of postoperative adjuvant radiation therapy to skin grafts used for wound closure after the resection of soft-tissue sarcomas. The intervals between grafting and the initiation of radiation ranged between 3 and 20 weeks, and 4 patients received chemotherapy at the same time as their radiation. Ten of the 12 irradiated grafts remained intact after the completion of therapy. One graft had several small persistently ulcerated areas that required no further surgical treatment, and one graft required a musculocutaneous flap for reconstruction of a persistent large ulcer. Acute radiation effects on the grafted skin sometimes developed at slightly lower doses than usually seen with normal skin, but these acute effects necessitated a break in therapy on only five occasions. Concurrent chemotherapy and a relatively short interval between grafting and the initiation of radiation seemed to contribute to more severe radiation reactions. This experience indicates that postoperative adjuvant radiation therapy can be delivered to skin grafted areas without undue fear of complications, especially if the graft is allowed to heal adequately prior to initiating therapy and if chemotherapy is not given in conjunction with radiation.

Adolescent↗
PubMed1986

Pregnancy after breast reconstruction with a transverse rectus abdominis musculocutaneous flap.

The transverse rectus abdominis musculocutaneous flap has been used for breast reconstruction with increasing frequency in recent years. It has not previously been reported whether or not an abdominal wall weakened by the transfer of this flap can withstand the added stress of pregnancy. An experience with one such patient who successfully carried a pregnancy to term is described.

Abdominal Muscles↗
PubMed1986

The reversal of an Adriamycin induced healing impairment with chemoattractants and growth factors.

Rats treated with 8 mg/kg Adriamycin intravenously 4 days prior to chamber implantation develop impaired wound healing in a wound chamber model. In this study, the effects on healing of supplemental platelet derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), epidermal growth factor (EGF), and insulin were evaluated in chambers extracted from Adriamycin-treated rats 10 and 20 days after implantation. The effects of individual factors, combinations of factors, and different concentrations of TGF-beta were evaluated. The parameters evaluated included collagen content, protein content, cellular proliferation rate, chamber histology, and collagen types. Supplemental TGF-beta alone reversed much of the healing deficit noted. A minimum concentration of 100 ng/ml TGF-beta was required to significantly reverse this deficit. PDGF and EGF alone had no effect. Addition of PDGF and TGF-beta in combination stimulated a significantly higher level of collagen deposit than TGF-beta alone. Addition of EGF in combination with PDGF and TGF-beta restored collagen deposition to 86% of normal. No synergism was seen between TGF-beta and EGF unless PDGF was also present. These data suggest that growth factors contained in platelets may play key roles in initiating the wound healing response and may have clinical utility in healing deficit states.

Animals↗
PubMed1986

Doxorubicin-induced impairment of wound healing in rats.

The mortality rate induced by 3 doses of iv doxorubicin was evaluated in F344 rats, and a dose of 8 mg doxorubicin/kg body weight was the maximum dose tolerated with an acceptable mortality rate. Rats treated with 8 mg doxorubicin/kg prior to or on the day of wounding demonstrated decreased wound breaking strength in incisional wounds at all intervals after wounding. Decreased amounts of collagen and DNA and less cellularity were noted in wound chambers from rats treated in the same manner. In both the incisional wound and wound chamber models, rats treated with doxorubicin 7 days after wounding showed a less dramatic healing impairment. No difference in collagen types was noted between chambers from the doxorubicin-treated and untreated rats. Doxorubicin also produced a significant reduction in platelet and white blood cell counts 1 week after it was administered. The data indicate that doxorubicin impedes healing by decreasing wound cellularity and collagen synthesis.

Animals↗
PubMed1986

Preoperative or postoperative doxorubicin hydrochloride (adriamycin): which is better for wound healing?

The purpose of this study was to determine if any interval between preoperative or postoperative administration of doxorubicin hydrochloride (Adriamycin) and wounding would limit the impairment in healing induced by Adriamycin. The question was evaluated in 7 cm incisional wounds on the dorsal midline of rats. Preoperative Adriamycin was administered 42, 28, 21, 14, and 7 days before wounding, and wound breaking strengths (WBS) of the incisional wounds were measured 7, 18, and 28 days after wounding. Postoperative Adriamycin was administered 0, 7, 14, 21, and 28 days after wounding, and WBS were measured 7, 14, 28, 35, and 42 days after wounding. A similar and significant degree of impairment was induced in healing by all preoperative Adriamycin regimens evaluated. Postoperative Adriamycin administered up to 21 days after wounding induced a healing deficit that manifested 1 to 2 weeks after Adriamycin administration. Adriamycin administered 28 days after surgery induced no demonstrable impairment in WBS. In addition, Adriamycin never decreased the WBS of a wound after a certain degree of strength had been obtained. These results lead us to warn against the use of preoperative Adriamycin and support the use of postoperative Adriamycin administered 28 days after a surgical procedure.

Animals↗
PubMed1985

Surgical delay and arachidonic acid metabolites: evidence for an inflammatory mechanism: an experimental study in rats.

In a rat skin flap model, surgical delay produced an increase in the production of arachidonic acid metabolites, with a derangement of the normal equilibrium between PGE2 and PGF2 alpha and a marked increase in the vasoconstrictive substance, thromboxane. During the delay period, there is a gradual decrease in tissue levels toward normal. Subsequent elevation of the delayed flap produces a blunted response in thromboxane production, an increase in PGE2 levels and increased flap survival. Acute elevation of an undelayed flap produced more marked elevation of all metabolites, with prolonged elevation of the vasoconstrictive PGF2 alpha and thromboxane, progressive ischemia and decreased flap survival. A key role in inflammation, mediated by these inflammatory mediators, is postulated in the mechanism of delay.

Animals↗
PubMed1985

The importance of recognising renal oncocytomas.

Oncocytomas of the kidney are infrequently reported tumours. They have distinct clinical and pathological features, but most cases have been discovered retrospectively. Nine series have been analysed (including four cases in Norwich) to define the features of these tumours. One of our cases is noteworthy because it is the largest individually reported tumour of this type and it contained a large cyst. Oncocytomas are benign and have an excellent prognosis. Failure to identify this subgroup may bias the perceived effectiveness of treatment for renal carcinoma.

Adenoma↗
PubMed1984

The detrimental effect of cigarette smoking on flap survival: an experimental study in the rat.

Cigarette smoking is commonly prohibited after surgery involving flaps. This admonition against smoking has been justified on the theoretical grounds that flap survival could be decreased by the cutaneous vasoconstriction and increased platelet aggregation produced by smoking cigarettes. A smoke chamber was constructed to evaluate directly the effect of intermittent cigarette smoke exposure on the survival of a McFarlane flap on the dorsum of a rat. The O2, CO2 and temperature were monitored in the chamber during smoke exposures and consistently approximated values seen in room air. Average flap survival at 7 days in control rats not exposed to cigarette smoke was 75.2% while flap survival decreased to 40.1% in rats intermittently exposed to cigarette smoke. The difference was statistically significant (p less than 0.01). Changes in carboxyhaemoglobin levels similar to those observed in human smokers were also found in the smoke-exposed rats. These findings support the concept that post-operative cigarette smoking is detrimental to flap survival.

Animals↗
PubMed1984

Prostanoid derivatives in experimental flap delay with formic acid.

The physiological changes that allow increased flap survival after flap delay have never been clearly defined. Inflammation has been postulated as a critical factor in flap delay and prostaglandins are known to be mediators of the inflammatory response. To evaluate the role of prostanoid derivatives in experimental flap delay, 0.2% formic acid was injected under the outline of modified McFarlane flaps in 20 rats and saline was injected under the flap outline in 20 control rats. Two weeks later the flaps were raised on all the rats. Average flap survival one week after flap elevation was 65.5% after formic acid delay and 42.9% after saline delay. Biopsies were taken from the flaps both during the delay period and after flap elevation. The specimens were stained for PGE2, PGF2 alpha and thromboxane. Changes noted in the levels of these prostanoid derivatives suggest that they may indeed mediate flap delay.

Animals↗
PubMed1984

Ectropion and epiphora in McArdle's syndrome.

Ectropion is unusual in young individuals. Recently, we treated a 19-year-old male college student for epiphora due to bilateral ectropion associated with McArdle's syndrome, a myophosphorylase deficiency. To our knowledge, there have been no previous reports of ectropion and epiphora as a result of this rare glycogen-storage disease.

Adult↗
PubMed1984

The treatment of ulcers in patients with mycosis fungoides with split-thickness skin grafts.

Five patients have recently been treated at this institution for skin ulcerations caused by mycosis fungoides and its treatment with total body electron beam radiation therapy. Both the disease and its treatment can injure epidermal appendages as well as the blood supply to the skin. As a result of this potential damage, there was initial concern that skin grafts might not take and donor sites might not heal in these patients. Though skin grafting has not been universally successful, we have been able to skin graft the majority of the ulcerated lesions in these patients with good results. Donor sites have healed, though more slowly than usual. Skin grafting can be effective for treating ulcers in patients who have undergone total body electron beam radiation therapy for mycosis fungoides.

Adult↗
PubMed1984

Stamey endoscopic bladder neck suspension for stress incontinence.

Sixty female patients with clinically demonstrable stress incontinence of urine have had a Stamey operation during the last 3 years. The results have been good in curing stress incontinence, whilst the majority of the failures have been in patients with severe detrusor instability or a chronic cough. There have been few post-operative complications and urodynamic studies have shown improved cough urethral profiles and no evidence of bladder outflow obstruction. The Stamey procedure can be recommended as the initial operation for surgically curable incontinence. Mild bladder instability is not a contraindication to the operation and it is also useful in elderly, unfit or obese patients.

Adult↗
PubMed1981

Malignant neoplasms of the major salivary glands.

Between January 1, 1968 and December 31, 1978, 42 patients with malignant lesions involving the major salivary glands were seen at the Medical College of Virginia. A 60% 2-year survival and a 42% 5-year survival were noted. Histologic type was the major determinant of survival. Symptoms other than a painless mass, a largest dimension greater than 4 cm, older age, and clinical spread outside the gland were all suggestive of both a more malignant histologic type and a worse prognosis. Based on these observations, a plan is proposed for the diagnostic approach and treatment of salivary gland masses that is based on the mode of presentation and histologic findings.

Adenocarcinoma↗