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Biomedical subjects

B Davidson

Publications and source records attributed to B Davidson.

At least 19 recordsLinked to original sources
PubMed1992

Prognostic significance of anastomotic recurrence from colorectal adenocarcinoma.

A retrospective analysis of the prognostic significance of anastomotic recurrence in 50 patients with colorectal adenocarcinoma was conducted from 1970 to 1987. All primary cancers were located above 10 cm from the anal verge. Forty anastomotic recurrences (80 percent) followed resection of sigmoid or proximal rectal tumors. The overall disease-free interval was 13 months, with 90 percent of recurrences diagnosed within 24 months of the primary resection. Forty-five recurrences (90 percent) were associated with synchronous or metachronous metastases. Overall median survival following the recurrence was 16 months--37 months if the anastomosis was the only recurrence site. Of five patients alive without evidence of disease, all were asymptomatic, and recurrence was confined to the anastomosis. In conclusion, anastomotic recurrence following resection of colorectal adenocarcinoma frequently heralds disseminated disease but can be potentially resected for cure if it is the only site in an otherwise asymptomatic patient.

Adenocarcinoma↗
PubMed1992

Value of exfoliative cytology for investigating bile duct strictures.

The cause of a biliary tract stricture may be difficult to determine radiologically. Exfoliative biliary cytology was evaluated in 62 patients (median age 65 years, range 30-94) with biliary tract strictures presenting to the Hepatobiliary Unit between January 1984 and December 1989. Bile samples were taken during endoscopic retrograde cholangiopancreatography (ERCP) in 42 patients, percutaneous cholangiography in 14, and both in six. The site of stricturing was upper third of the bile duct in 43% (n = 27), middle third in 10% (n = six), and lower third in 47% (n = 29). Of the 47 patients with radiological appearances of a malignant stricture, 22 (47%) had histological confirmation by biopsy either under computed tomography guidance, at endoscopy, at operation, or at necropsy. Fourteen of the 47 patients had positive cytology (30%). In seven patients cytology alone established the presence of malignancy (15%) and in the other seven positive cytology was confirmed by histology. The addition of cytology to tissue biopsy therefore allowed malignancy to be confirmed in 29 of the 47 patients (62%). None of the 15 patients subsequently shown to have benign disease had positive cytology. Sensitivity of the technique was 30% and specificity 100%. Samples for exfoliative cytology are simple to obtain, the results are highly specific and should be a routine part of the investigation of biliary strictures.

Adult↗
PubMed1992

A prospective controlled study comparing brush and bile exfoliative cytology for diagnosing bile duct strictures.

Imaging of biliary strictures may suggest malignancy but cytology can provide a tissue diagnosis. The aim of this study is to compare the diagnostic value of brush cytology and bile cytology. Thirty two patients (20 males, 12 females, median age 66 years, range 31-84) with biliary strictures at endoscopic retrograde cholangio pancreatography (24) or percutaneous transhepatic cholangiography (8) had bile cytology and brush cytology. Brushings were taken using a modified Geenan cytology brush (6 Fr gauge, Wilson Cook) passed alongside a guide wire placed through the stricture. Bile was aspirated after insertion of an internal/external catheter or an endoprosthesis. Bile and brushings were examined by one experienced cytologist (AD) and was reported as positive or negative for malignant cells. Twenty nine patients had malignant strictures. Sixteen were confirmed by histology and 13 had malignancy suggested by clinical follow up. Three patients had resection of histologically benign strictures. The overall sensitivity of brush cytology (17 of 29 positive, 59%) was significantly greater than bile cytology (seven of 29 positive, 24%) (p < 0.01) as was the diagnostic accuracy (63 v 31%, p < 0.01). None of the patients had positive bile cytology with negative brush cytology. There were no procedure related complications and the average sampling time once the guide wire had been inserted was less than five minutes. It is concluded that brush cytology is more sensitive than bile cytology and with the technique described is safe and rapid.

Adult↗
PubMed1992

The effect of the illness episode approach on Medicare beneficiaries' health insurance decisions.

This article reports on a quasi-experimental test of the Illness Episode Approach (IEA), a new approach to providing Medicare beneficiaries with information about the financial consequences of alternative health care coverage decisions. Beneficiaries were randomly assigned to free, three-hour workshops, half using materials developed through application of the IEA, half using traditional comparative information on insurance options. Analysis of data collected before and after the workshops indicates that participants in the Illness Episode sessions were more likely to drop duplicative coverage, to spend less on premiums, and to report that their decisions to change coverage had met their expectations. The entire sample of workshop participants showed significant increases in knowledge of Medicare and their own insurance, as well as improved satisfaction with the cost of their health care coverage.

Aged↗
PubMed1992

The incidence of myopia in the Israel Air Force rated population: a 10-year prospective study.

It is important to define the risk in pilots of becoming myopic in order to determine the need for yearly screening, and to predict pilot eligibility in environments where the use of corrective lenses may present problems. We conducted a prospective study of 1400 air force personnel followed for 10 years, who could be divided into three major groups; those with 20/20 vision in both eyes, those with 20/25 in one eye only and whose vision was 20/20 using both eyes together, and those who were accepted despite the fact that they required corrective lenses. Over the 10-year period, 23.1% of those with 20/25 visual acuity in one eye needed corrective lenses, significantly more than the 7.4% observed in those with 20/20 vision in both eyes (relative risk 3.1, 95% confidence interval 2.2-4.3, p less than 0.0000). The prevalence of corrective lenses increased until age 26. We conclude that 7.4% of pilots will become myopic over a 10-year period if accepted with 20/20 vision in both eyes. The risk, however, is much higher in those with incipient growth myopia starting in one eye at entry. Therefore, the annual screening of visual acuity in air force personnel is essential.

Adolescent↗
PubMed1991

Identification of male-factor semen samples prior to insemination and in vitro fertilization.

Semen analyses carried out as part of the clinical in vitro fertilization or intrauterine insemination protocols provide important information that determine the type of clinical treatment of the male partner and the sperm processing method. It is postulated that the sperm of male-factor patients cannot survive hypoosmotic stress conditions because of defective sperm membrane function. To test this, 0.1 ml of semen from each of 102 patients was placed in 1.0 ml of 150 mosmol/liter eosin citrate fructose solution and incubated for 30 min at 37 degrees C. The percentage viability of the sperm cells was then determined. The results indicated that patients with two or more abnormal semen parameters had a significantly lower percentage viability while in the hypoosmotic solution (40.6 +/- 4.7%), in contrast to non-male-factor patients (69.0 +/- 1.6%). Donor sperm (N = 32) serving as controls (73.3 +/- 2.1%) had a viability in hypoosmotic solution similar to that of non-male-factor patients. The data suggest that sperm of male-factor patients are less able to survive the hypoosmotic stress conditions as shown by the percentage viability in hypoosmotic solution and emphasize the importance of using less stressful sperm processing methods for in vitro fertilization or insemination in these patients.

Cell Membrane↗
PubMed1991

Surgical emergencies in liver disease.

In this chapter the surgical management of bleeding oesophageal varices, ruptured hepatocellular carcinoma and fulminant liver failure have been discussed. Bleeding oesophageal varices can usually be successfully treated with vasopressin, balloon tamponade and injection sclerotherapy. Emergency surgery should be considered if two courses of injection sclerotherapy have failed to achieve haemostasis. Stapled oesophageal transection and portosystemic shunting are currently the two most popular procedures. The former is associated with a lower morbidity and mortality as well as a lower incidence of subsequent encephalopathy. Ruptured hepatocellular carcinomas are usually associated with liver cirrhosis and impaired liver function. Selective coeliac axis cannulation followed by embolization of the hepatic artery branches supplying the tumour is an effective method of achieving haemostasis and is associated with a lower morbidity and mortality than emergency hepatic artery ligation or liver resection. If haemostasis is achieved by embolization the patient may subsequently be assessed for an elective resection of the tumour. Fulminant liver failure may be managed by supportive medical therapy or orthotopic liver transplantation. Patients whose liver failure is graded as mild (grade I) should be treated by medical therapy, whereas those with severe liver damage (grades III and IV) should be assessed for transplantation. Accurate monitoring of the patient's clinical progress and prognostic indicators are vital in deciding whether conservative treatment should be continued or liver transplantation performed.

Carcinoma, Hepatocellular↗
PubMed1991

Cardiovascular adaptations in Andean natives after 6 wk of exposure to sea level.

Six male Quechua Indians (34.0 +/- 1.1 yr, 159.5 +/- 2.1 cm, 60.5 +/- 1.6 kg), life-long residents of La Raya, Peru (4,350-m altitude with an average barometric pressure of 460 Torr), were studied using noninvasive methods to determine the structural and functional changes in the cardiovascular system in response to a 6-wk deacclimation period at sea level. Cardiac output, stroke volume, and left ventricular ejection fractions were determined using radionuclide angiographic techniques at rest and during exercise on a cycle ergometer at 40, 60, and 90% of a previously determined maximal O2 consumption. Subjects at rest were subjected to two-dimensional and M-mode echocardiograms and a standard 12-lead electrocardiogram. Hemoglobin and hematocrit were measured on arrival at sea level by use of a Coulter Stacker S+ analyzer. After a 6-wk deacclimation period, all variables were remeasured using the identical methodology. Hemoglobin values decreased significantly over the deacclimation period (15.7 +/- 1.1 to 13.5 +/- 1.2 g/dl; P less than 0.01). The results indicate that the removal of these high-altitude-adapted natives from 4,300 m to sea level for 6 wk results in only minor changes to the cardiac structure and function as measured by these noninvasive techniques.

Acclimatization↗
PubMed1991

Hepatolithiasis associated with anomalous biliary anatomy and a vascular compression. Hepatolithiasis and anomalous anatomy.

Biliary tract abnormalities occur in about one of every three people, usually being minor and of no clinical significance. Major abnormalities, however, may present in an unusual manner and provide a major hazard to the unsuspecting surgeon. A patient presenting with cholangitis without jaundice or abnormal liver function tests is reported. Endoscopic retrograde cholangiography failed to demonstrate any bile ducts in the right postero-lateral segments of the liver, the "naked segment sign". A percutaneous transhepatic cholangiogram demonstrated a stricture obstructing the right posterior segmental hepatic duct with hepatolithiasis above the stricture. At operation an anomalous vessel was found at the site of the stricture. This case highlights the unusual way in which biliary tract anomalies may present and the importance of adequate pre-operative investigation.

Aged↗
PubMed1991

Controversy in the management of cholangitis secondary to hydatid daughter cysts.

A 36 year old Cypriot woman, resident in the U.K. since the age of three years, presented with pyrexia, jaundice and upper abdominal pain. On ultrasound examination the biliary tree was dilated, contained sludge and a cystic lesion was present in the liver. An endoscopic cholangiogram showed multiple filling defects in the bile duct which were not felt to be removable endoscopically and a nasobiliary drain was therefore inserted. On resolution of the cholangitis with drainage and antibiotics a laparotomy was performed. The right lobe of the liver was largely replaced by a multiloculated cyst and the bile duct contained multiple hydatid daughter cysts. A right hepatectomy was performed with t-tube drainage of the evacuated bile duct. She made an uneventful recovery and has had no problems on subsequent follow up. Histology confirmed an intrabiliary rupture of a hydatid liver cyst. Cholangitis secondary to daughter cysts is a rare but recognised complication of hydatid liver cysts. Management of hydatid liver cysts by formal resection is controversial but may be preferable in this situation.

Adult↗
PubMed1990

Dose-limiting toxicity of rifabutin in AIDS-related complex: syndrome of arthralgia/arthritis.

We studied the tolerance of humans to rifabutin, a rifamycin with antimycobacterial and in vitro anti-HIV activity. Sixteen subjects with AIDS-related complex were treated for 4-66 weeks with stepwise increasing oral doses of rifabutin from 300 to 2400 mg/day. The highest dose attained was twice that previously reported for humans. Serum and cerebrospinal fluid levels of drug were detected by high-pressure liquid chromatography. A reversible syndrome of arthritis/arthralgia, not previously described, was seen in most (nine out of 10) of those given doses exceeding 1050 mg/day. Uveitis and aphthous stomatitis developed at doses of approximately 1800 mg in two of those with joint manifestations. Typical manifestations of Reiter's syndrome were not seen in any patient. An orange-tan skin pigmentation was almost universal. Other toxicities resembled those previously associated with rifampin. Serum levels did not approach those found to inhibit HIV significantly in vitro. No consistent antiviral or immunological effects were observed; even at the highest doses, rifabutin did not appear to inhibit cellular immunity. Rifabutin was well tolerated at daily doses blow 1 g.

AIDS-Related Complex↗
PubMed1990

Ethical reasoning associated with the feeding of terminally ill elderly cancer patients. An international perspective.

An international nursing research study examined the ethical decision-making of "good and experienced" registered nurses in eight countries. The subjects were asked about their decision to feed or not to feed a hypothetical terminally ill, mentally alert, elderly cancer patient who refuses to eat. Cultural variations were demonstrated in the decisions as well as differences in ethical justification. The majority of nurses who would not feed appeared to use the principle of autonomy, whereas nurses who would feed the patient used beneficence as justification. Conditions under which nurses would change their decision to either feed or not feed the patient against her will included doctor's orders and lack of peer support for the decision. The majority of nurses clearly experienced a dilemma.

Adult↗
PubMed1989

Efficacy of rifabutin in the treatment of AIDS-related complex.

We performed a phase 1-2 antiviral dose escalation trial of rifabutin, a rifamycin antibiotic with anti-HIV-1 activity in vitro. We followed 16 men with AIDS-related complex (ARC) for a mean duration of 29 weeks; the maximum toxicity-limited dose of rifabutin was 2400 mg/day, which was achieved in two patients. There was some evidence of anti-HIV-1 activity in two patients, one of whom had an improvement in immune status, but 11 of the 16 patients showed a deterioration in either virologic or immunologic status. The majority of the patients under study remained clinically stable during the trial, but there was clinical deterioration in the three who entered with CD4 cell counts of less than 100 x 10(6)/l. On the basis of this trial, rifabutin as a single antiviral agent does not appear to be beneficial to ARC patients.

AIDS-Related Complex↗
PubMed1988

Essential fatty acids modulate apomorphine activity at dopamine receptors in cat caudate slices.

We have used a classical neurotransmitter release model to investigate the effect of dietary polyenoic fatty acids on the sensitivity of the presynaptic dopamine autoreceptor in slices of cat caudate nucleus. Maximum inhibition of [3H]dopamine release was seen only in animals fed a diet containing post delta-6-desaturation fatty acids of both the w3 and w6 series. The removal of either or both groups of fatty acids resulted in attenuation of sensitivity of the autoreceptor to apomorphine. We propose that a balance of w3 and w6 fatty acids is required to maintain normal dopaminergic function in the cat caudate nucleus.

Animals↗