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Biomedical subjects

R McKenzie

Publications and source records attributed to R McKenzie.

At least 37 records · Page 2Linked to original sources
PubMed1999

Incidence of intracranial bullet fragment migration.

Migration of retained bullets or bullet fragments may present as a complication of gunshot wounds to the head. This phenomenon has been reported in cases of abscess formation or retained copper fragments. Management of such migratory fragments is controversial. The purpose of this study is to determine the incidence of fragment migration in a population of neurosurgical patients treated for gunshot wounds to the head. Two-hundred and thirteen cases treated at Detroit Receiving Hospital between 1985 and 1987 were reviewed. Each patient treated had initial and one week follow-up imaging studies. Nine cases of documented migratory intracranial bullet fragments were identified. Thus, the incidence in this population is 4.2%. The fragments in eight cases were composed of copper, and in the remaining case, lead. No case was associated with an abscess. Fragments in the anterior fossa were found to migrate towards the sella turcica, while those of the middle fossa and posterior hemispheres migrate towards the confluence of sinuses (Torcula Herophili). Fragment migration was documented as early as 36 h post-injury. Based on this study, we recommend serial imaging studies to look for migrating bullet fragments and surgical removal aided by intra-operative ultrasound to localize the fragment when possible.

Adult↗
PubMed1998

Lateralization in chicks and hens: new evidence for control of response by the right eye system.

Domestic chicks show marked lateralization of visually evoked behaviour: left eye use is associated with, and has advantage for, the detection of novelty; right eye use is associated with the use of selected cues to determine what response should be given. Experiments undertaken to see how far such lateralization might be a transient feature of development showed similar patterns in both adults and chicks: (i) use of the right, but not the left, frontal field allowed the inhibition of pecks at a familiar social partner; (ii) in distant viewing, there was spontaneous preference for more use of the left eye when the social partner was familiar rather than unfamiliar. The chick data, in particular, support the hypothesis that the visual system fed by the right eye is especially competent in the control of response. This is shown by the ability of birds that are using the right eye to inhibit approach to an entirely novel potential social partner, and inhibit pecks at a familiar partner. The resemblances between chick and hen are sufficient to show that the basic adult pattern is already present in the young chick: the various developmental changes in features of lateralization, such as days of bias to control by one or other hemisphere, thus do not cause the appearance of the adult pattern.

Animals↗
PubMed1998

Droperidol-ondansetron combination versus droperidol alone for postoperative control of emesis after total abdominal hysterectomy.

STUDY OBJECTIVES: To investigate the hypothesis that the combination of ondansetron and droperidol would be more effective than droperidol alone in reducing nausea and vomiting. DESIGN: Randomized, doubleblind study. SETTING: Magee-Womens Hospital, Pittsburgh, Pennsylvania. PATIENTS: 160 healthy, ASA physical status I and II, female patients scheduled for total abdominal hysterectomy. INTERVENTIONS: After induction of anesthesia with propofol, Group 1 received intravenous (i.v.) droperidol 1.25 mg plus i.v. ondansetron 4 mg. Group 2 received i.v. droperidol plus i.v. saline. MEASUREMENTS AND MAIN RESULTS: The complete response (no emesis, no rescue) for Group 1 was 36 of 80 patients (45%) versus 30 of 80 patients (38%) in Group 2 (p = 0.21). In Group 1, 42 of 80 patients (53%) required rescue antiemetic as compared with 44 of 80 patients (55%) in Group 2 (p = 0.43). There were 72 total rescues in Group 1 versus 73 in Group 2, (p = 0.24). Mean time until first rescue was 578 +/- 429 minutes in Group 1 and 418 +/- 354 minutes in Group 2, (p = 0.03). In Group 1, 81 % (34/42) were rescued for nausea only versus 90% (39/44) of Group 2 (p = 0.16). In Group 1, 21% of patients (17/80) had at least one emetic episode versus 34% (27/80) of Group 2 patients (p = 0.05). There were 31 emetic episodes in Group 1 versus 72 episodes in Group 2. (p = 0.02). Mean time to the first emetic episode was 699 +/- 403 minutes in Group 1 and 616 +/- 376 minutes in Group 2, (p = 0.23). CONCLUSION: For patients undergoing total abdominal hysterectomies, the addition of ondansetron to droperidol increases the time until first rescue and reduces the number of emetic episodes, as well as the percentage of patients, having at least one emetic episode.

Adult↗
PubMed1998

A randomized, prospective comparison of pain after gasless laparoscopy and traditional laparoscopy.

STUDY OBJECTIVE: To compare pain after laparoscopic tubal ligation by gasless laparoscopy versus carbon dioxide (CO2) pneumoperitoneum. DESIGN: Prospective, randomized, single-blind comparison (Canadian Task Force classification I). SETTING: Private obstetric-gynecology hospital associated with a university resident teaching program. PATIENTS: Women age 21 to 42. INTERVENTION: Single-puncture laparoscopic tubal ligation was performed with a silicone elastomer band. Gasless laparoscopy was performed with a Laprolift and traditional laparoscopy with CO2 pneumoperitoneum. Postoperative pain in the shoulder and periumbilical and lower pelvic regions was measured by visual analog scale on the day of surgery and postoperative days 1, 2, 3, 7, and 14. MEASUREMENTS AND MAIN RESULTS: Of the 67 patients, 54 provided visual analog scales for analysis, 30 in the gasless group and 24 in the traditional group. No statistical difference was seen in scores for shoulder, periumbilical, and pelvic pain between techniques. CONCLUSION: Patients undergoing gasless laparoscopy and traditional laparoscopy experience similar postoperative pain.

Adult↗
PubMed1998

Combination therapy with famciclovir and interferon-alpha for the treatment of chronic hepatitis B.

Interferon-alpha (IFN-alpha) treatment results in long-term remissions in only 25%-40% of patients with chronic hepatitis B virus (HBV) infection. Famciclovir, the oral prodrug of penciclovir, inhibits HBV DNA replication. Five adults with chronic HBV infection in whom previous IFN-alpha therapy had failed were treated in a pilot study of overlapping IFN-alpha and famciclovir therapy totaling 20 weeks. HBV DNA levels decreased by 0.9 log units during the initial 4-week period of famciclovir alone, followed by a further decrease of 1.8 logs during the middle 12-week period of combination therapy. HBV DNA rose by 0.9 log during the final 4-week period of IFN-alpha alone. Two patients cleared HBV DNA, and their liver disease improved by clinical and histologic criteria. The combination of famciclovir and IFN-alpha appeared to be at least additive in suppressing HBV DNA. Efficacy trials of combination therapy with famciclovir and IFN-alpha are warranted.

2-Aminopurine↗
PubMed1998

A comparison of the efficacy, safety, and patient satisfaction of ondansetron versus droperidol as antiemetics for elective outpatient surgical procedures. S3A-409 and S3A-410 Study Groups.

UNLABELLED: Two identical, randomized, double-blind, placebo-controlled studies enrolled 2061 adult surgical outpatients at high risk of postoperative nausea and vomiting (PONV) to compare i.v. ondansetron 4 mg with droperidol 0.625 mg and droperidol 1.25 mg for the prevention of PONV. The antiemetic drugs or placebo were administered i.v. 20 min before the induction of anesthesia with a barbiturate compound, followed by maintenance with N2O/isoflurane/enflurane. Nausea, emetic episodes, adverse events, and patient satisfaction were analyzed for the 0 to 2 h and 0 to 24 h postoperative periods. In the 0 to 2 h postoperative period, there was a complete response (no emesis or rescue antiemetic) in 46% of subjects given placebo (P < 0.05 versus antiemetic groups), in 62% given ondansetron, in 63% given droperidol 0.625 mg, and in 69% given droperidol 1.25 mg (P < 0.05 versus ondansetron). In the 0 to 24-h postoperative period, there were no significant differences in complete response between the ondansetron and droperidol 0.625 or 1.25 mg groups; all groups remained superior to placebo. The proportion of patients without nausea during the 0 to 24 h postoperative period was greater in the antiemetic groups compared with the placebo group; however, droperidol 1.25 mg was more effective than ondansetron 4 mg or droperidol 0.625 mg (43% vs 29% or 29%, respectively). Headache incidence was higher in the ondansetron group compared with either droperidol group. Patient satisfaction scores did not differ significantly among antiemetic treatment groups, although all were superior to placebo. In conclusion, all antiemetic treatment regimens were superior to placebo for the prevention of PONV in the immediate postoperative period; however, droperidol 1.25 mg was more efficacious than ondansetron during the early recovery period (0-2 h). There were no significant differences between ondansetron and either droperidol dose for emesis prevention during the 0 to 24 h postoperative period. IMPLICATIONS: More than 2000 patients at high risk of postoperative nausea and vomiting were given either placebo, ondansetron 4 mg, or droperidol 0.625 mg or 1.25 mg i.v. before the administration of general anesthesia. After surgery, the incidence of nausea, vomiting, medication side effects, and patient satisfaction were evaluated for 24 h. Droperidol 0.625 or 1.25 mg i.v. compared favorably with ondansetron 4 mg i.v. for the prevention of postoperative nausea and vomiting after ambulatory surgery.

Adolescent↗
PubMed1997

Effect of propofol for induction and ondansetron with or without dexamethasone for the prevention of nausea and vomiting after major gynecologic surgery.

STUDY OBJECTIVES: To test the hypothesis that for major gynecologic surgery the combination of propofol for induction, ondansetron, and dexamethasone would be a more effective antiemetic combination than propofol for induction, ondansetron, and saline; and to determine if a propofol induction of anesthesia improved our previously reported results when thiamylal was the induction drug. DESIGN: Double-blind, randomized study. SETTING: Magee-Womens Hospital, Pittsburgh, Pennsylvania. PATIENTS: 80 healthy ASA physical status I, II, and III female inpatients scheduled for major gynecologic surgery. INTERVENTIONS: After induction of anesthesia with propofol, Group 1 received intravenous (IV) ondansetron 4 mg and saline, and Group 2 received IV ondansetron 4 mg followed by IV dexamethasone 20 mg. MEASUREMENTS AND MAIN RESULTS: For Group 1 and Group 2, respectively, no emesis and no rescue occurred in 15 (37.5%) and 21 (52.5%) patients (p = 0.13); emesis occurred in 7 (17.5%) Group 1 patients and 5 (12.5%) Group 2 patients, rescue antiemetic 23 (57.5%) Group 1 patients and 19 (47.5%) Group 2 patients. Nausea was reported by 31 (77.5%) Group 1 patients and 30 (75%) Group 2 patients. CONCLUSIONS: The hypothesis that the addition of dexamethasone to the propofolondansetron combination would significantly reduce postoperative nausea and vomiting (PONV) was not confirmed. A propofol induction of anesthesia resulted in a comparable incidence of PONV when compared with our previously reported results using thiamylal for induction of anesthesia for women having major gynecologic operations.

Adolescent↗
PubMed1997

Immunotherapy of recurrent genital herpes with recombinant herpes simplex virus type 2 glycoproteins D and B: results of a placebo-controlled vaccine trial.

To determine the safety, immunogenicity, and efficacy of a recombinant herpes simplex virus type 2 glycoprotein D and B vaccine in the treatment of recurrent genital herpes, a randomized, placebo-controlled trial was held at two referral centers. Healthy patients with 4-14 recurrences per year received injections of both glycoproteins in MF59 adjuvant or of MF59 alone at 0, 2, 12, and 14 months. For 18 study months, the rate and number of recurrences, the duration and severity of the first confirmed recurrence, vaccine immunogenicity, and rates of local and systemic reactions were determined. The monthly rate of recurrences was not significantly improved, but the duration and severity of the first study outbreak was reduced significantly by vaccination. Glycoprotein-specific and neutralizing antibodies were boosted by vaccination for the duration of the study. This vaccine is safe and immunogenic and ameliorated an observed first postvaccination genital recurrence, but it does not reduce recurrence frequency.

Adult↗
PubMed1997

Intravenous dolasetron for the prevention of postoperative nausea and vomiting after outpatient laparoscopic gynecologic surgery.

The newer 5-hydroxytryptamine type 3 (5-HT3) antagonists are sometimes considered for routine prophylaxis of postoperative nausea and vomiting (PONV) in high-risk patients. This multicenter, randomized, double-blind, placebo-controlled study compared the efficacy and safety of three single intravenous (IV) doses of dolasetron mesylate salt (12.5, 25, or 50 mg) for the prevention of PONV in 635 females undergoing outpatient laparoscopic gynecologic surgery. Antiemetic efficacy was evaluated over a 24-h postoperative period by recording the number and timing of emetic episodes; effects on nausea were evaluated by a visual analog scale (VAS). The proportion of complete responders (no emetic episodes and no escape medication in 24 h) was significantly higher with each dolasetron mesylate dose (> 50% for each dose; P < or = 0.0003) than with placebo (30.6%). Fewer patients given dolasetron required or requested escape antiemetic medication compared with placebo (P < 0.0003). Dolasetron-treated patients had significantly (P < 0.0357) lower median postdose maximum nausea VAS scores compared with placebo-treated patients. Patient satisfaction with dolasetron was high and, overall, was significantly (P = 0.0131) greater than that with placebo. Dolasetron was an effective and well tolerated preventive treatment for PONV resulting from laparoscopic gynecologic surgery.

Adult↗
PubMed1997

Histopathologic changes associated with fialuridine hepatotoxicity.

Chronic hepatitis B is a widespread viral illness with the serious sequelae of cirrhosis and hepatocellular carcinoma. Current therapy with interferon is not universally efficacious, and this has led to the evaluation of other antiviral agents. A recent Phase II trial of the nucleoside analogue, fluoroiodoarabinofuranosyluracil (fialuridine, FIAU) was halted because of the sudden development of severe multisystem toxicity characterized by hepatic failure, lactic acidosis, and pancreatitis, which resulted in the deaths of five patients. We systematically evaluated pre- and post-therapy biopsy, explant, and autopsy specimens from the 15 patients involved in this trial to define the hepatic changes of fialuridine toxicity and to determine whether the degree of pre-existing hepatitis contributed to the severity of toxicity. Severe hepatotoxicity from fialuridine was characterized by hepatomegaly with diffuse, predominantly microvesicular steatosis, hepatocellular glycogen depletion, marked bile ductular proliferation, and cholestasis. Ultrastructural examination revealed intracytoplasmic lipid droplets and marked mitochondrial injury. Patients in whom severe toxicity did not develop mainly showed changes caused by the underlying chronic hepatitis B alone. There was a subtle increase in the amount of microvesicular steatosis in two of six patients with mild or no symptoms of toxicity. The microscopic and ultrastructural pattern of injury and systemic symptoms in patients with fialuridine toxicity are consistent with severe mitochondrial and metabolic derangements. Similar hepatic pathologic findings have been reported rarely for other antiviral nucleoside analogues, which suggests that the mechanisms of toxicity might be related.

Adult↗
PubMed1996

Brief retention deficits associated with cyclically recurring left hemisphere events.

In the chick, brief episodes of enhanced recall ("retrieval events") recur approximately every 25 min in recall via the right hemisphere, and every 16 min in recall via the left. These events coincide with, and probably cause, the numerous transitions between memory phases described in the chick.; The most important of these is the transition to long-term memory, which is sometimes held to occur in chicks at about 50 min after learning, a transition picked out as unique by a variety of effects of amnesia-inducing agents, and by a brief impairment ("dip") in recall at 55 min. We used a single trial passive avoidance task, involving bead pecking, to show that in chicks using only one eye, such dips occur not only at 55 min (in right-eyed chicks only) but also after each of the subsequent series of left hemisphere events (in left-eyed chicks only). Dips in recall appear to result when processes that are initiated by left hemisphere retrieval events result in hemispheric interaction, with one hemisphere (which can be either left or right) holding an inadequate trace (e.g., as a result of monocular training). Recall tests under such conditions may involve both the adequate and the inadequate trace, so that performance is impaired.

Animals↗
PubMed1996

Droperidol/ondansetron combination controls nausea and vomiting after tubal banding.

The antiemetic activity of droperidol is attributed to antagonizing the dopaminergic neurons of the chemoreceptor trigger zone. Ondansetron is a serotonin (5HT) receptor antagonist at both peripheral and central 5-HT3 receptor sites with no known action on dopamine-mediated activity. We hypothesized that the combination of these two antiemetics would be more effective than droperidol alone. Women with ASA classified physical status I or II, scheduled for laparoscopic tubal banding, participated in a randomized double-blind clinical trial using a standardized anesthesia regimen. Within 15 min after induction of anesthesia, Group 1 (n = 60) received IV droperidol 1.25 mg and ondansetron 4 mg and Group 2 (n = 60) received IV droperidol 1.25 mg and saline. Before surgery and during recovery at 1, 2, and 24 h, emetic episodes, nausea, pain, drowsiness, medications taken, and adverse events were recorded. The complete response (no emesis, no rescue) for Group 1 was 55 of 60 (91.6%) versus 47 of 60 (78.3%) in Group 2 (P = 0.04). No patient needed rescue antiemetic medication in Group 1, whereas 5 of 60 (8.3%) patients were rescued in Group 2 (P = 0.03). There were seven emetic episodes in five patients in Group 1 and 30 emetic episodes in 12 patients in Group 2 over the 24-h study period (P = 0.03). The time to the first emetic episode was more than twice as long for Group 1 than Group 2 (P = 0.03) and total nausea scores were lower in Group 1 than Group 2 (P = 0.01). The droperidol/ondansetron combination was significantly superior to droperidol in complete response, time to and number of emetic episodes, and the incidence and severity of nausea in women having tubal banding.

Antiemetics↗
PubMed1995

Hepatic failure and lactic acidosis due to fialuridine (FIAU), an investigational nucleoside analogue for chronic hepatitis B.

BACKGROUND: We describe severe and unexpected multisystem toxicity that occurred during a study of the antiviral nucleoside analogue fialuridine (1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouracil, or FIAU) as therapy for chronic hepatitis B virus infection. METHODS: Fifteen patients with chronic hepatitis B were randomly assigned to receive fialuridine at a dose of either 0.10 or 0.25 mg per kilogram of body weight per day for 24 weeks and were monitored every 1 to 2 weeks by means of a physical examination, blood tests, and testing for hepatitis B virus markers. RESULTS: During the 13th week lactic acidosis and liver failure suddenly developed in one patient. The study was terminated on an emergency basis, and all treatment with fialuridine was discontinued. Seven patients were found to have severe hepatotoxicity, with progressive lactic acidosis, worsening jaundice, and deteriorating hepatic synthetic function despite the discontinuation of fialuridine. Three other patients had mild hepatotoxicity. Several patients also had pancreatitis, neuropathy, or myopathy. Of the seven patients with severe hepatotoxicity, five died and two survived after liver transplantation. Histologic analysis of liver tissue revealed marked accumulation of microvesicular and macrovesicular fat, with minimal necrosis of hepatocytes or architectural changes. Electron microscopy showed abnormal mitochondria and the accumulation of fat in hepatocytes. CONCLUSIONS: In patients with chronic hepatitis B, treatment with fialuridine induced a severe toxic reaction characterized by hepatic failure, lactic acidosis, pancreatitis, neuropathy, and myopathy. This toxic reaction was probably caused by widespread mitochondrial damage and may occur infrequently with other nucleoside analogues.

Acidosis, Lactic↗
PubMed1995

Traumatic rupture of the thoracic aorta: should one always operate immediately?

Although the traditional therapy for blunt traumatic rupture of the thoracic aorta (TRA) is immediate operative repair, there may be a selective role for delayed repair, particularly in patients with head trauma, respiratory failure, or cardiac dysfunction. The present study examines the hypothesis that TRA can be managed by selective delayed operative repair. Clinical data were collected from 59 consecutive patients with TRA at a regional trauma unit. All TRAs were at the aortic isthmus. Patients were retrospectively classified into three groups: group I (n = 12) included patients who either arrived in extremis or rapidly became unstable during triage; group II (n = 3) included patients who had no contraindications to early repair and underwent repair at the time of diagnosis; and group III (n = 44) consisted of patients who because of concomitant injuries or sepsis required initial admission and management in the intensive care unit until their clinical status had improved sufficiently to allow for deliberate delayed operative repair of the TRA. The delay ranged from 1 day to 7 months. Eight patients have yet to undergo repair and remain well at follow-up from 1 to 4 years. Overall survival rates in groups I, II, and III were 17%, 100%, and 82%, respectively. The surgery-related mortality rate in group III was 10% (three patients). Only two (4.5%) patients in group III died as a result of a ruptured aorta within 72 hours of admission. In conclusion, contrary to surgical doctrine, TRA may not require immediate operative repair in all cases, but may instead be managed selectively depending on the patient's clinical status.

Adult↗
PubMed1995

Antiemetic efficacy of a droperidol-morphine combination in patient-controlled analgesia.

STUDY OBJECTIVES: To evaluate the antiemetic effectiveness and side effects of adding low-dose droperidol to morphine delivered via a patient-controlled analgesia (PCA) device. DESIGN: Randomized, double-blind, clinical study. SETTING: University-affiliated women's hospital. PATIENTS: 60 healthy women, 18 to 60 years of age, who underwent total abdominal hysterectomy with a standardized anesthetic regime. INTERVENTIONS: After surgery, the control group (n = 20) had access via PCA to two cartridges, each containing morphine 1 mg/ml and saline 1 ml. The two treated groups (n = 20 each) had access via PCA to either droperidol 0.5 mg or droperidol 1 mg added to two cartridges containing morphine 1 mg/ml. MEASUREMENTS AND MAIN RESULTS: Preoperative data, including each patient's history of nausea and vomiting with and without previous anesthesia, motion sickness, smoking, and alcohol intake, and date of her last menstrual period, were obtained. All patients received a standardized anesthetic with droperidol 0.5 mg given at closure of the peritoneum. Among those patients who received droperidol added to morphine for their postoperative analgesic regimen, fewer required rescue antiemetic medication (p < 0.05, test of trend in proportions), and they had a lower incidence of vomiting (p < 0.05, test of trend in proportions), as well as a decrease in the number of times a rescue antiemetic was needed during the 24-hour postoperative period (linear trend, p = 0.013). CONCLUSIONS: An intermittent intake of low-dose droperidol with morphine given via a PCA delivery system in two treatment groups gave evidence for a dose-response relation between the amount of droperidol added and the proportion of patients needing a rescue antiemetic. The same result applied to the proportion of patients having an emetic episode and the number of times a rescue antiemetic had to be administered. There was no evidence that the low dose of droperidol added to morphine delivered via a PCA device increased unwanted side effects.

Adolescent↗