Search PubMed⌕ Search

Biomedical subjects

H M Clarke

Publications and source records attributed to H M Clarke.

47 records · Page 3Linked to original sources
PubMed1991

Perfusion parameters and pressure at zero flow in canine gracilis muscle flaps.

The perfusion parameters and pressure at zero flow were examined in island gracilis muscle flaps in dogs under sodium pentobarbital anesthesia. Complete surgical isolation of the muscle preparation was obtained. Normal blood flow in denervated muscle in situ was 8.0 +/- 0.8 ml/min/100 g tissue as measured by electromagnetic blood flowmetry. The artery supplying each flap was occluded with a microclip and the drop in pressure distal to the clip was observed. The lowest pressure obtained following occlusion was the pressure at zero flow. A positive pressure at zero flow in the vascular bed was thereby identified at a pressure of 10.3 +/- 1.2 mm Hg.

Animals↗
PubMed1990

Acute management of pediatric hand burns.

The pattern of injury seen in pediatric hand burns differs from adults because scald burns are most common. Many of these are difficult to assess at initial presentation. In addition, children develop less stiffness in response to immobilization. For these reasons, we have developed a conservative, expectant approach for treating most pediatric hand burns. Meticulous wound care, positioning, splinting, and exercise are required to safely accomplish the goals of rapid healing with minimal loss of function. These regimens are adapted specifically to suit the age of the child and are applied by the burn team. Normal hand function can be obtained in the majority of cases.

Burns↗
PubMed1989

Ketoconazole in the treatment of osteomyelitis due to Candida albicans.

Osteomyelitis caused by Candida albicans is a rare condition. The authors report its occurrence as an infective complication in the fractured phalanx of a 3-year-old boy. The infection was first thought to be due to Staphylococcus aureus, but a course of cloxacillin was unsuccessful, and when cultures of the injured finger grew C. albicans, a 3-month course of ketoconazole orally was begun. Ketoconazole was prescribed because, unlike amphotericin B, the antibiotic usually used in such cases, it is not nephrotoxic, it can be taken orally and it has proved successful in other reported cases of osteomyelitis due to C. albicans. The boy's infection resolved and fracture healing was confirmed radiologically.

Candidiasis↗
PubMed1985

Delayed neovascularization in free skin flap transfer to irradiated beds in rats.

A model for the study of neovascularization with a normal epigastric free flap set into an irradiated defect in the Fischer F344 rat is presented. In this model, both the administration of radiation and the flap transfer mimic the clinical situation. Significantly less tissue survives loss of the complete vascular pedicle at the second to fourth days following flap creation in rats with an irradiated bed. Later survival is not different from controls. Delayed neovascularization is proposed as the mechanism responsible for this effect during the period corresponding to the onset of the late phase of the response to skin radiation in rats. That neovascularization does occur, although delayed, suggests that the induced endarteritis may not be as important as previously suggested.

Animals↗
PubMed1985

Assessing the pressure at zero flow in canine epigastric skin flaps.

The pressure at zero flow was examined using three independent techniques in island epigastric skin flaps in dogs under sodium pentobarbital anesthesia. (i) The flap was perfused from a reservoir which was varied in height to supply a range of pressures. The corresponding flows were measured by electromagnetic blood flowmetry and the pressure at zero flow was determined by extrapolation to zero flow. (ii) Arterial inflows as low as 2.2 microL/min were delivered by a Harvard pump and corresponding pressures were measured. The pressure at zero flow was determined by inspection. (iii) The artery supplying the flap was occluded with a microclip and the plateau following the decay of pressure was read as the pressure at zero flow. The pressure decay technique was the simplest, most reproducible method and was verified by the other two methods. It gave a pressure at zero flow of 5.8 +/- 0.4 mmHg (0.77 +/- 0.05 kPa). The critical closing pressure is discussed and related to the pressure at zero flow.

Animals↗
PubMed1982

A study of blood flow and pressure in the vessels supplying a free flap.

A canine inferior epigastric free flap was studied to determine the normal hemodynamic parameters in a free flap operation. Following revascularization, mean arterial blood flow in the vessels supplying the flap was 4.1 to 4.8 ml/min/100 gm of tissue. Meticulous suture anastomosis did not adversely affect mean flow. Furthermore, resistance in the flap did not change throughout the procedure. Further studies, using this and other models, are underway to examine the hemodynamics of failing flaps. The current study provides the baseline data necessary for this continuing work, which may provide an insight into preventive or therapeutic measures directed at improving free flap survival.

Abdomen↗
PubMed1981

Survival following vascular compromise in an island skin flap.

A model for evaluating vascular compromise in an island skin flap is presented. Survival is seen earliest following loss of the artery. Both artery and vein ligation groups show equal survival from the second day on with complete survival after the third day. Longer healing, up to 5 days, is required before the loss of both vessels can be withstood. Survival of island flaps in Wistar rats is not dependent on circulation through the vascular pedicle after 3 to 5 days.

Animals↗
PubMedDate not supplied

Autotransplantation of epithelial cells in the pig via an aerosol vehicle.

A new method of delivery of epithelial suspensions with use of an aerosolization apparatus was examined in the pig. Full-thickness pig skin was harvested, and an epithelial suspension was created using standard techniques of dispase and trypsin. Twenty-four hours after skin harvest, four full-thickness wounds were created on the flanks of the pig. The control wound was sprayed with a solution without epithelial cells. The three experimental wounds were sprayed with epithelial cell suspensions (integral 10(6) cells/suspension). Weekly evaluation with photographs, biopsies, and tracings were done for 4 weeks. At 10 weeks, the entire process was repeated with new wounds on the pig's back. Thirty-five wounds in five pigs were evaluated: 10 control (5 flank, 5 back) and 25 experimental (15 flank, 10 back). Control wounds healed by contraction alone, with epithelium at the edges only. After 4 weeks, an open area remained. Central epithelial islands developed in experimental wounds at 2 weeks. These islands coalesced to close the wounds by 4 weeks. Histology at 1 week showed groups of epithelial cells deeply embedded in granulation tissue. These groups became immature epithelial layers on the surface by 2 weeks, and all layers of epithelium were present by 4 weeks. Overall, flank experimental wounds epithelialized sooner, but contracted at the same rate as control wounds. In conclusion, epithelial cells can be delivered by an aerosolization apparatus and remain viable and proliferative in a pig model.

Aerosols↗
PubMedDate not supplied

Safety and pharmacokinetics of EMLA in the treatment of postburn pruritus in pediatric patients: a pilot study.

The purpose of this study was to determine the safety and pharmacokinetics of a eutectic mixture of local anesthetics (EMLA) used to ameliorate postburn pruritus after application onto newly formed, intact skin in children. EMLA was applied once to an itchy site where healed skin had formed. Serial blood samples were collected to measure lidocaine, prilocaine, o-toluidine, and methemoglobin. Maximal plasma concentration, minimal plasma concentration, time to achieve the maximal plasma concentration, elimination half-life, and area under the concentration-time curve were calculated. Vital signs, oxygen saturation, clinical signs of hypoxia, and itch intensity were measured. Five children had 15.7 +/- 2.54 g (+/- SD) of EMLA applied to a skin surface area of 93.0 +/- 37.0 cm2. Lidocaine and prilocaine concentrations were below toxic levels; o-toluidine was not detected. Methemoglobin remained between 1 and 3%; patients did not exhibit any clinical signs of hypoxia. Mean oxygen saturation was 98.9 +/- 0.01%. The mean number of pruritic episodes and antihistamine breakthrough doses were greater in the 2 prestudy control days compared with study day 3 (P = 0.01 and P = 0.03, respectively). Skin at the site of EMLA application remained anesthetized for 12 to 13 hours. In this small pilot study, EMLA seems to be a safe, novel treatment for postburn pruritus in burned children when applied to newly healed, intact skin.

Administration, Topical↗
PubMedDate not supplied

Relaxation following contraction in tonically contracted smooth muscle from the bovine trachea.

Isometric tension was recorded from strips of bovine tracheal smooth muscle in which the tone had been artificially raised by agonist drugs such as histamine and carbachol. Application of exogenous acetylcholine produced a biphasic response consisting of an initial contraction followed by a more prolonged relaxation before tone was restored to normal. Atropine blocked both components of the biphasic response to exogenous acetylcholine. Tetrodotoxin blocked neither phase of the response to exogenous acetylcholine even though a similar biphasic response to electrical stimulation was severely disrupted. Application of exogenous substance P produced a biphasic response of similar magnitude and form to that produced by acetylcholine. Application of exogenous histamine (tone raised by carbachol) also produced a biphasic response although higher concentrations were required to produce a relaxation of equal magnitude to that produced by acetylcholine. It is concluded that the inhibitory component of the biphasic response to exogenous acetylcholine occurs as a non-specific sequel to contraction.

Acetylcholine↗