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Biomedical subjects

R McKenzie

Publications and source records attributed to R McKenzie.

At least 19 recordsLinked to original sources
PubMed1992

Regulation of complement activity by vaccinia virus complement-control protein.

A major protein secreted by vaccinia virus-infected cells has structural similarity to the super-family of complement-control proteins. This vaccinia complement-control protein (VCP) was studied to determine how it regulates complement activation. VCP was bound by C4b and C3b and served as a cofactor with factor I in cleaving these two molecules. VCP inhibited the formation and accelerated the decay of the classical C3 convertase. It also accelerated decay of the alternative pathway convertase, although higher concentrations were apparently needed. In vitro, therefore, VCP interfered with the classical and alternative complement pathways at several steps. In vivo, this interference may increase the virulence of vaccinia virus by enabling it to escape attack by the host's complement system.

Complement Activation↗
PubMed1992

Prophylactic intravenous ondansetron in female outpatients undergoing gynaecological surgery: a multicentre dose-comparison study.

The efficacy and safety of prophylactic intravenous ondansetron in preventing postoperative nausea and vomiting was investigated in a randomized, stratified, double-blind, placebo-controlled, dose-comparison study of 580 ASA physical class I and II female outpatients undergoing gynaecological surgery and receiving general anaesthesia. Patients received either ondansetron 1, 4 or 8 mg, or placebo i.v. immediately prior to a standardized technique for induction and maintenance of anaesthesia. All patients were intubated and received nitrous oxide and a narcotic. All doses of ondansetron were significantly more effective than placebo in preventing emesis over the 24 h postoperative period. Ondansetron significantly decreased nausea and emesis scores over 24 h postoperatively without causing sedation. No changes in laboratory parameters (haematology, blood chemistry, and liver enzymes) or vital signs (heart rate, blood pressure, and respiratory rate) were observed. Headache and dizziness were the most common side-effects; however, their incidence was the same as with placebo. Ondansetron was generally well tolerated, as evidenced by an adverse event, laboratory safety, and vital sign profile similar to placebo. Ondansetron 4 mg was found to be the optimal prophylactic i.v. dose for female outpatients over the entire 24 h postoperative period. Higher doses may offer an added benefit in some patients, such as those with a history of nausea and vomiting following general anaesthesia.

Adult↗
PubMed1992

Side effects of morphine patient-controlled analgesia and meperidine patient-controlled analgesia: a follow-up of 500 patients.

Many physicians, Certified Registered Nurse Anesthetists (CRNAs), and registered nurses have the clinical impression that either morphine sulfate or meperidine hydrochloride is a better drug to control postoperative pain. In this study, we evaluated pain relief and side effects for these two drugs to assess their potential differences. CRNAs conducted a structured interview of 500 female patients 24 hours after major gynecologic, urologic, or breast surgery. Patients' responses on 4-point scales of none, mild, moderate, and severe were collected for pain intensity, degree of nausea, severity of vomiting and itchiness, and degree of sedation experienced since the operation. There were 91 patients who received morphine patient-controlled analgesia (PCA) and 409 patients administered meperidine PCA. No statistically significant differences for pain intensity, degree of nausea, severity and incidence of vomiting, or degree of sedation were found. However, a significant difference was found in the incidence rates of mild itchiness, which occurred more frequently in the morphine PCA group (P less than .001). Patients vomited more often after vaginal hysterectomy than patients having laparotomy, major oncology, or tuboplasty surgeries (P less than .05), and vaginal repair patients reported more vomiting than patients having major oncology or tuboplasty surgeries. Clinical impressions that either morphine or meperidine should be the preferred treatment for patients following gynecologic operations was not found by a 24-hour review of 500 patients for pain relief and side effects. Although mild itchiness occurred more frequently in the morphine PCA group, treatment was rarely necessary.

Adult↗
PubMed1991

The causes of death in patients with human immunodeficiency virus infection: a clinical and pathologic study with emphasis on the role of pulmonary diseases.

The clinical records and autopsy data of 75 patients dying with AIDS were reviewed to determine the frequency of individual diseases diagnosed premortem and postmortem, the significance of pulmonary processes found in the lungs at autopsy, and the clinical and pathologic causes of death. Cytomegalovirus (CMV) infection was identified histologically either premortem or postmortem in 81% of patients. The lungs and adrenal glands were infected most commonly. Only one-half of CMV infections were recognized premortem. Pneumocystis pneumonia and Kaposi sarcoma occurred in 68% and 59% of patients, respectively, but were not unsuspected premortem in any patient. Visceral involvement with Kaposi sarcoma, however, was frequently recognized only at autopsy. While disseminated M. avium-intracellulare infection was common (31% of patients), histologically documented pulmonary disease was uncommon (3% of patients). Cryptococcal infection, diagnosed in 10 patients, was confined to the central nervous system in only 1 patient. Toxoplasma, in contrast, infected the brain of only 6 patients. All 75 patients had one or more disease processes identified in their lungs or pleurae at autopsy. These processes included opportunistic infections in 76% of patients, neoplasms in 37% (Kaposi sarcoma in 36% and lymphoma in 3%), and other processes in 60%. The most prevalent pathogen, CMV was found in pulmonary tissue from 44 patients and caused significant disease in 21 patients. Five patients died due to CMV pneumonia. Pneumocystis carinii was found at autopsy in 24 patients. In spite of treatment, pneumocystis pneumonia was fatal in 11 patients. One patient died with concomitant CMV and pneumocystis pneumonia. Kaposi sarcoma, identified in the lungs of 23 patients, led to death in 5 patients via upper airway obstruction, hemorrhage, or parenchymal destruction. Other fatal pulmonary processes included bacterial pneumonia in 9 patients, idiopathic diffuse alveolar damage in 5, cryptococcosis in 2, and pulmonary hemorrhage in 1. Specific clinical criteria were used to determine the cause of death due to organ system failure. Fifty-one percent of patients died due to respiratory failure; 16% from neurologic disease; 17% from hypotension that was not caused by respiratory, neurologic, or cardiac disease; and 3% from cardiac dysfunction. Thirteen percent of deaths did not meet the clinical criteria defining these 4 categories. This clinical assessment was combined with autopsy data to identify specific diseases as causes of death.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Prevention of hypertension and vascular changes by captopril treatment.

Treatment of female spontaneously hypertensive rats (SHR) and control Wistar-Kyoto (WKY) rats with captopril was carried out by the addition of the drug in the drinking water throughout pregnancy and lactation and after weaning. At 28 weeks of age, average systolic blood pressure of treated SHR was 113 +/- 3 mm Hg, which was below that of control SHR (188 +/- 3 mm Hg) and WKY rats (124 +/- 3 mm Hg). Body weight and heart rate of the SHR were not affected by the treatment. Tissue level of catecholamines was increased by captopril treatment in the superior cervical ganglia but remained unchanged in the plasma, heart, mesenteric arteries, and the adrenal glands of both SHR and WKY rats. Left ventricular weight, wall thickness, and internal diameter of the left ventricle in the SHR were reduced by the treatment. Morphometric measurements of the mesenteric arteries showed that vascular alterations present in the control SHR were prevented by the treatment. In the superior mesenteric artery and large mesenteric artery, smaller lumen size at maximal relaxation found in the control SHR was normalized to the level of the WKY rats. Hypertrophy of the medial wall in the superior mesenteric, large and small mesenteric arteries, and an increase in the number of smooth muscle cell layers in the large mesenteric artery of the SHR were prevented by the treatment. Perfusion study of the mesenteric vascular bed showed that reactivity of these vessels to norepinephrine was reduced, and sensitivity to norepinephrine (as determined by the effective dose that causes 50% of maximal response) was increased in the SHR by captopril treatment. Sensitivity of the tail artery in response to norepinephrine was not altered by the treatment. We conclude that long-term treatment with captopril of SHR before and after birth prevented the development of hypertension, structural and functional alterations of the mesenteric arteries, and cardiac hypertrophy.

Animals↗
PubMed1978

A safer method for paracervical block in therapeutic abortions.

Adverse reactions to paracervical block, including death, are believed to be dose related. By using a modified jet injector instead of the standard syringe-and-needle technique, we obtained equal analgesia with one fifth of the standard milligram dosage of lidocaine in patients undergoing therapeutic abortion. Blood lidocaine levels as determined by gas chromatography were reduced by two thirds with jet injection. These results led us to conclude that jet injection for paracervical block is safer than the syringe-and-needle technique.

Abortion, Therapeutic↗
PubMed1977

Anaesthesia for dilatation, evacuation and curettage in outpatients: comparison of subanaesthetic doses of ketamine and sodium methohexitone-nitrous oxide anaesthesia.

Sub-dissociative doses of ketamine compared unfavourably with methohexitonenitrous oxide anaesthesia for dilatation, evacuation and curettage. We could not separate the desirable effects of analgesia and amnesia from the unwanted dream effects and visual disturbances. Although the time of clinical recovery was similar, the Trieger Motor Test revealed a delay in return to normal in both groups.

Adolescent↗
PubMed1977

Ketamine as the sole anaesthetic agent for laparoscopic sterilization. The effects of premedication on the frequency of adverse clinical reactions.

Ketamine, as the sole anaesthetic agent, was assessed in a double-blind study of 135 female patients who underwent laparoscopic sterilization. The patients were allocated randomly to one of four groups according to the type (pentobarbitone or droperidol) and route (i.v. or i.m.) of premedication. In addition all the patients received hyoscine i.m. Neither pentobarbitone nor droperidol prevented adverse emergence reactions and the total frequency of dream-like activity. However, patients who received pentobarbitone i.v. did not recall unpleasant dream-like activity. Patients who received droperidol i.v. had the shortest recovery time after ketamine anaesthesia. There was a high incidence of visual disturbances in all groups. Droperidol protected against the initial increase of heart rate, and pentobarbitone against the increase in arterial systolic pressure associated with ketamine.

Adult↗
PubMed1976

Dissociation of urate from sodium transport in the rat proximal tubule.=.

The tubular transport of urate and sodium was examined by clearance, free-flow micropuncture, intratubular microinjection and precession techniques in control rats and in rats receiving a new uricosuric diuretic, indanyloxyacetic acid (MK-196). The i.v. infusion of MK-196 (50 mg/kg of body wt/hr) resulted in significant increases in the fractional excretion of sodium (FENa) from 0.98 +/- 0.01 to 11.86 +/- 2.88% (P less than 0.001) and in FEurate from 14.1 +/- 1.03 to 56.0 +/- 2.86% (P less than 0.001). End-proximal tubular fluid to plasma inulin (TF/Pinulin) ratios were 2.43 +/- 0.15 and 2.51 +/- 0.10 in control and drug-treated animals, respectively (P = NS). Total urinary urate recovery after MK-196 administration was higher following microinjections of [2-14C] urate into early proximal tubule sites: 70.5 +/- 2.7% in controls vs. 84.9 +/- 0.9 (P less than 0.001), and after microinjections into late proximal tubule sites: 82.8 +/- 2.9% vs. 91.3 +/- 1.9 (P less than 0.05). Urinary precession of urate from inulin was demonstrable following placement of isotopes of these compounds on the surface of the kidney in controls, but was abolished by MK-196. This agent, therefore, inhibits the reabsorption and secretion of urate in the proximal convoluted tubule, the net effect being a marked increase in urinary urate excretion. By contrast, its inhibitory effect on sodium reabsorption is exerted at a site or sites distal to the accessible portion of the proximal tubule. The demonstration of reduced urate reabsorption and normal sodium reabsorption in the proximal tubule suggests that the reabsorption of these constituents of the glomerular filtrate is not intimately linked at this nephron site.

Animals↗
PubMedDate not supplied

Pneumatosis intestinalis associated with needle catheter jejunostomy tubes: CT findings and implications.

The CT findings of pneumatosis intestinalis (PI) associated with needle catheter jejunostomy tubes (NCT) are described in two patients. Each case had cyst-like intramural gas collections associated with the NCT. Neither case had focal bowel wall thickening or portal or mesenteric free air, and there was no evidence of intestinal necrosis. Our findings suggest that cyst-like intramural gas collections associated with NCT represent a benign form of PI.

Catheters, Indwelling↗