Search PubMed⌕ Search

Biomedical subjects

R M Green

Publications and source records attributed to R M Green.

At least 163 records · Page 9Linked to original sources
PubMed1990

Factors determining survival after ruptured aortic aneurysm: the hospital, the surgeon, and the patient.

The 10-year experience of a single community was reviewed and a multivariate analysis was performed to determine the relative importance of clinical and environmental factors in mortality after ruptured abdominal aortic aneurysm resection. Ruptured aneurysms were repaired in 243 patients in six area hospitals (one university, five community) by 25 surgeons (16 vascular, 9 general). Overall, 30-day mortality was 55% (133/243). Although the mortality by hospital ranged from 44% to 68%, these differences were not statistically significant. However, significant variations occurred in the mortality rates of individual surgeons, ranging from 44% to 73%. The mortality rate for the vascular surgeons was less than that of the general surgeons, 51% versus 69% (p less than 0.05). Clinical factors were evaluated, and the most significant parameters were systolic blood pressure, presence of chronic obstructive lung disease, and history of chronic renal insufficiency. These results support the implication that the degree of specialization of the surgeon and the preexisting health of the patient are the most important determinants of survival after ruptured abdominal aortic aneurysm. The size and sophistication of the hospital appear to be less influential factors.

Aged↗
PubMed1990

Method in bioethics: a troubled assessment.

This discussion is a critical assessment of the methods employed by some leading writers in the field of bioethics. The author agrees with those in the field who regard its primary or essential method as moral philosophy, but he nevertheless finds a prevalent tendency among bioethical writers merely to apply received moral principles to issues and to avoid penetrating theoretical analysis, even when such analysis is unavoidably required. He explains these deficiencies in terms of the exigencies of interdisciplinary work and the affinity of much early bioethics with policy- or legislatively-oriented "public ethics". The discussion ends with a call for increased theoretical sophistication in this field.

Bioethics↗
PubMed1990

Multiple intracerebral hemorrhages after smoking "crack" cocaine.

After smoking "crack" cocaine and consuming large quantities of ethanol, a 36-year-old man developed multiple, bilateral, deep, and superficial cerebral hematomas. He was hypertensive for several days, but angiography revealed no evidence of vascular malformation or vasculitis. The multifocality of the hematomas and lack of underlying disease suggest that the hemorrhages resulted from cocaine-induced acute hypertension or arterial spasm, possibly potentiated by heavy ethanol consumption.

Adult↗
PubMed1990

Comparison of infrainguinal graft surveillance techniques.

One hundred seventy-seven patients with infrainguinal bypass grafts were followed by use of standard graft surveillance techniques to learn more about the natural history of hemodynamic abnormalities in the patient with no symptoms. A decrease in the ankle/brachial pressure ratio of 10% or more was considered an abnormal evaluation. Results of the duplex scan were interpreted as abnormal when the peak systolic flow velocity was greater than 120 cm/sec or less than 40 cm/sec. There were 18 graft thromboses (10%) during the period of observation, and nine of these grafts were successfully revised or replaced. Recurrent symptoms prompted graft revision in 20 additional patients, and 18 of these reoperations were successful. Twenty-nine of the 38 reoperations occurred within the first 18 months of the study. The primary cumulative patency rate was 86% at 1 year and 66% at 5 years. The secondary cumulative patency rate was 91% at 1 year and 80% at 5 years. Sudden graft occlusion occurred in five patients after a normal ankle/brachial index. Most of 90 patients with abnormal ankle/brachial indexes reverted to normal at the next visit. Nineteen of the 26 that did not, had significant graft problems, but only eight patients had operable conditions, and five of the eight already had occluded grafts. No patient with a normal ankle/brachial index and duplex scan results had graft occlusion before their next surveillance visit. If the duplex scan outcome was abnormal but the ankle/branchial index normal the incidence of sudden graft occlusion was 4%. In contrast, if the duplex scan outcome was abnormal and the ankle/brachial index is reduced, then the risk of graft occlusion is 66%.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Vessel Prosthesis↗
PubMed1989

Comparative cariogenicity and dental plaque-forming ability in gnotobiotic rats of four species of mutans streptococci.

The four species, each represented by two strains, all produced high levels of fissure caries in the upper and lower jaws of gnotobiotic Fisher rats. Streptococcus rattus strains and Streptococcus mutans NCTC 10832 gave low levels of approximal caries, whereas Streptococcus cricetus, Streptococcus sobrinus and Strep. mutans NCTC 10449 gave high levels. The only strains to produce buccal surface lesions were Strep. sobrinus and Strep. cricetus. All strains were able to form dense plaque in the central fissure of the second molar. Strep. cricetus, Strep. rattus and Strep. sobrinus strains were capable of producing smooth-surface plaque. This difference in plaque-forming ability did not correlate precisely with differences in cariogenicity, and such differences occurred between strains of the same species.

Animals↗
PubMed1989

Attitudes of some young female bank employees to dentistry.

Structured interviews were undertaken with one hundred 18-30-year-old females, seeking their views on dental care. Almost all regarded their own past experience as affecting their general level of dental anxiety. Over half were anxious about visiting the dentist and almost all of these were anxious before entering the surgery. The Anxious emphasized the negative features in dental care and the practice environment whereas the Non-anxious concentrated on positive features, particularly their relationship with the dentist. Many spontaneously commented that their attitudes had been improved by changing dentists, although some still remained anxious. 'Worst visits' had frequently occurred early in their lives. Appearance was of prime importance; function was ignored. Interviewees believed that visiting the dentist would be eased by lower costs, more convenient hours, better surroundings in the practice and improved techniques to make dentistry more comfortable.

Adolescent↗
PubMed1989

Alteration in doxorubicin and doxorubicinol plasma concentrations with repeated courses to patients.

Fifteen cancer patients were studied following repeated courses of doxorubicin (12-44 mg/m2) (together with other anticancer agents) to consider the possibility of enhanced metabolism as a cause of the previously reported reduction in doxorubicin plasma concentrations with repeated courses. Plasma doxorubicin and doxorubicinol concentrations were measured by a modified high-performance liquid chromatography/fluorescence method. The results presented confirmed the significant decline in doxorubicin plasma concentration-dose ratios measured 3 h after the 1-h infusion. Although the degree of this reduction varied markedly between patients, it was shown not to be associated with a rise in the plasma concentration-dose ratio of the major metabolite doxorubicinol or with altered renal and/or hepatic function, which may have influenced disposition. Alternative mechanisms that might explain the reduction in doxorubicin concentrations, such as increased doxorubicin clearance or volume of distribution, were not considered in the present study.

Adolescent↗
PubMed1989

Reexploration for thrombosis in carotid endarterectomy.

We reviewed the records of patients undergoing carotid endarterectomy and manifesting either postoperative stroke or thrombosis by oculopneumoplethysmography (OPG-Gee) to analyze the etiology of stroke and to determine the indications for reexploration. Of 900 consecutive elective endarterectomies performed during an 8-year period, 41 patients experienced a perioperative stroke, carotid thrombosis, or both. These patients were subdivided into three groups: group 1, 22 patients with perioperative stroke and carotid thrombosis; group 2, six patients with carotid thrombosis but without symptoms; and group 3, 13 patients with postoperative stroke but no thrombosis. In group 1, 17 patients were reexplored (group 1a), and five were observed without reexploration (group 1b). In group 2, three of the patients were reexplored (group 2a), and the remaining three were observed (group 2b). None of the group 3 patients were reexplored. In group 1a, four (23%) patients awoke from anesthesia with neurological deficits, whereas in group 3, nine (69%) patients awoke with such deficits. Follow-up at 30 days revealed that 76% of group 1a patients demonstrated improvement in symptoms, whereas similar results were seen in only 20% of group 1b patients and 23% of group 3 patients. These trends were maintained throughout the follow-up period of 1-5 years. Those patients who were asymptomatic, group 2, with thrombosis were more likely to have been operated on for asymptomatic carotid stenosis. with thrombosis were more likely to have been operated on for asymptomatic carotid stenosis. Thrombosis was the most common cause of postoperative stroke (63%) in patients after carotid endarterectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Results of supraceliac aortic clamping in the difficult elective resection of infrarenal abdominal aortic aneurysm.

We have used clamping of the aorta above the celiac axis (SC) in 30 of 431 elective resections of infrainguinal abdominal aortic aneurysms (AAA) during the past five years as an alternative to a difficult aortic cuff dissection. The results of SC clamping in these 30 patients are compared with the results of 379 routine aneurysm resections with infrarenal (IR) clamping and 22 additional aneurysm resections where the clamp was placed immediately above the renal arteries. These difficult cuff dissections occurred in 12 patients with inflammatory AAA, in 11 patients with juxtarenal AAA, and in seven patients with recurrent or noninfected false AAA of the proximal cuff. Patients with ruptured or suprarenal aneurysms and those undergoing combined operation for a visceral ischemic syndrome and an aneurysm were excluded from this study. Patients with SC clamping had similar operative mortality rates, comparable renal function, and frequency of cardiac events as patients with IR clamping. Blood loss was slightly higher in the SC group (p = 0.07) and serum aspartate amino transferase (AST) levels were three times higher than in the IR group; however, this was of no clinical significance. In contrast, those 22 patients whose aortas were clamped immediately above the renal arteries (AR) had higher perioperative mortality rates (2% IR, 3% SC vs 32% AR) and a higher incidence of kidney failure requiring dialysis (1% IR, 3% SC vs 23% AR). The mean values of serum creatinine and blood urea nitrogen were also significantly higher in the AR group when compared with both the IR and the SC groups (IR: 25 and 1.5 mg/dl, respectively; SC: 27 and 1.8 mg/dl; AR: 41 and 3.5 mg/dl). The single most important risk factor accounting for the differences between clamping above the celiac artery and clamping above the renal arteries was the presence of atherosclerotic debris in the nonaneurysmal, juxtarenal aortic segment. Clamping the aorta with juxtarenal atherosclerosis caused either atheroembolization to kidneys, legs, and intestine or injury to the aorta, renal arteries, or both; it was the cause of morbidity in all five cases of kidney failure requiring dialysis and accounted for all seven of the deaths in the AR group. SC clamping does not add risk to the patient undergoing resection of an infrarenal AAA and is the preferred method of achieving proximal control of the infrarenal aorta when a a hazardous cuff dissection is likely.(ABSTRACT TRUNCATED AT 400 WORDS)

Aorta, Abdominal↗
PubMed1988

Tooth wear and the position of the mental foramen.

Variation in the position of the mental foramen with respect to the teeth ("apparent" position) seems to be associated with race, but in the determination of this position, factors which affect the disposition of the teeth plainly have a bearing on the results. The apparent position was investigated in a sample of southern Chinese skulls of known age which were classified by the degree of tooth wear. Controlling for "true" position and size of the mandible, a highly significant correlation between wear and position was found, age and tooth size having no significant contribution as additional explanatory variables. The effect of tooth wear on the apparent position of the foramen may partly explain racial variation.

Adolescent↗
PubMed1988

A resolution of the ascertainment sampling problem: IV. Continuous phenotypes.

This paper considers ascertainment corrections for continuous phenotypes. Two main points are considered. The first is a discussion of what ascertainment corrections can be devised to ensure asymptotically unbiased parameter estimates when the nature of the ascertainment procedure is not known. The second is an analysis of the properties of various forms of ascertainment correction possible when the nature of the ascertainment procedure is known. Some ascertainment corrections are thus shown to be valid and others invalid.

Data Interpretation, Statistical↗
PubMed1988

Human central nervous system and plasma pharmacology of mitoxantrone.

Mitoxantrone 5-6 mg/m2 was administered IV to 10 consenting patients prior to surgical resection of an intracerebral tumor. Plasma pharmacokinetic parameters were calculated and concentration of mitoxantrone in intracerebral tumors was determined. Concentrations of mitoxantrone were also determined in autopsy tissues of one of the patients who expired 192 days after receiving the drug. The plasma pharmacokinetics were best described by a 3 compartment model, with a tl/2 gamma of 4.74 +/- 5.53 h. Mitoxantrone concentrations in the intracerebral tumors were potentially cytotoxic and ranged from 4 to 322 ng/g. In all but one case, mitoxantrone concentration was higher in tumor than in concurrent plasma samples. There was no obvious relation between tumor mitoxantrone concentration and peak plasma mitoxantrone concentration or time from mitoxantrone administration to tumor removal. Low grade gliomas and viable tumors tended to have lower mitoxantrone concentrations than did other tumor types and necrotic tumors. In the patient undergoing autopsy, highest mitoxantrone concentrations were found in liver, thyroid and heart.

Adult↗
PubMed1988

Renal clearance and protein binding of melphalan in patients with cancer.

The renal clearance of melphalan and the fraction unbound in plasma were determined after intravenous infusion of 5 mg/m2 over 5 min in nine patients with cancer to obtain information regarding the mechanism of renal handling of melphalan. Four of the patients underwent bone marrow transplantation and also received an IV dose of 220 mg/m2. Total melphalan clearance after the 5 mg/m2 dose ranged from 66.0 to 272 ml/min per m2; the percentage of the dose excreted unchanged in urine, from 2.5% to 92.8%; renal clearance, from 4.1 to 188 ml/min per m2; the fraction unbound in plasma, from 0.0598 to 0.460; and t1/2 beta, from 39.4 to 84.3 min. Unbound melphalan clearance and renal clearance calculated from the unbound fraction in plasma for each patient ranged from 441 to 3356 ml/min per m2 and 15 to 961 ml/min per m2 respectively and were not related to serum albumin, serum creatinine or creatinine clearance. The percentage of the dose excreted and melphalan renal clearance were not related to urine flow. There was evidence of active secretion of melphalan in the kidney an possible reabsorption. There were no significant paired differences in melphalan disposition between the high- and low-dose studies. Highly variable renal clearance involving active secretion may contribute in part to large interpatient differences in the total plasma clearance of melphalan in patients with cancer.

Adult↗
PubMed1988

Anomalous carotid-basilar anastomoses in cerebrovascular surgery.

Primitive embryonic anastomotic vessels between the internal carotid and basilar arterial systems occasionally persist into adult life. We encountered six such patients in a series of 765 carotid endarterectomies (0.8%). These arteries are named for the cranial nerves with which they run. The most commonly found vessel is the trigeminal artery, followed by the hypoglossal and proatlantal intersegmental arteries. The primitive otic artery is the rarest of the four anomalous vessels. These vessels are usually large and are associated with hypoplasia or aplasia of the normal intracranial anastomotic channels. Cerebral ischemia is common during temporary intraoperative carotid occlusion and was encountered in two of three patients who had intraoperative electroencephalographic monitoring. Thus cerebral ischemia should be anticipated during carotid cross-clamping and cerebral protective measures should be instituted when persistent primitive cranial vessels are encountered.

Basilar Artery↗
PubMed1988

Observations on cerebral computed tomography in patients having carotid endarterectomy.

A review was undertaken of all patients seen in our institution between January 1978 and March 1987 in whom a cerebral CT scan was obtained in association with elective carotid endarterectomy. Three hundred fifty-nine such patients were identified. In a subgroup of 89 patients who were neurologically normal after carotid endarterectomy, scans were performed at least 48 hours after surgery to quantitate the incidence of silent postoperative infarction. These scans were interpreted by one neuroradiologist. Preoperative cerebral CT scans showed ipsilateral infarction in 146 of 359 patients (40.6%). Ipsilateral infarction was most common in patients with stroke (76%) but was also seen in 32.8% of patients with transient ischemic attacks, in 9 of 40 patients (22.5%) with nonhemispheric symptoms, and in 9 of 45 patients (20%) with asymptomatic hemodynamically significant carotid stenosis. The postoperative stroke rate was not significantly increased by the presence of infarct on preoperative cerebral CT scan (2.6% vs 1.9%). New infarcts were seen on cerebral CT scanning after carotid endarterectomy in 2 of 89 patients with no detectable neurologic abnormality (2.3%). This study demonstrates a high frequency of ipsilateral infarction in patients having elective carotid endarterectomy, even in those patients with clinical symptom complexes thought by many physicians to be relatively benign (i.e., transient cerebral ischemia, nonhemispheric ischemia, and asymptomatic carotid stenoses).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗