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Biomedical subjects

D R Allen

Publications and source records attributed to D R Allen.

At least 19 recordsLinked to original sources
PubMed2002

Autosomal dominant myocardial disease diagnosed by fetal presentation of proband with an aneurysm of the muscular interventricular septum.

We describe an inherited form of a disorder in which four patients spanning three generations were affected with congenital myocardial disease. The youngest member of the family, diagnosed as a fetus with a large aneurysm of the muscular interventricular septum, demonstrates an antenatal pathogenic process. Study of the specific findings in each patient suggests that congenital aneurysms of the muscular interventricular septum may be in some way associated with specific developmental pathways of the heart. We believe that screening family members of patients with muscular interventricular septal aneurysms may be indicated to assess for silent myocardial disease.

Adult↗
PubMed1998

Abdominal aortic aneurysm rupture rates: a 7-year follow-up of the entire abdominal aortic aneurysm population detected by screening.

PURPOSE: The goal of the current study was to identify the risk of rupture in the entire abdominal aortic aneurysm (AAA) population detected through screening and to review strategies for surgical intervention in light of this information. METHODS: Two hundred eighteen AAAs were detected through ultrasound screening of a family practice population of 5394 men and women aged 65 to 80 years. Subjects with an AAA of less than 6.0 cm in diameter were followed prospectively with the use of ultrasound, according to our protocol, for 7 years. Patients were offered surgery if symptomatic, if the aneurysm expanded more than 1.0 cm per year, or if aortic diameter reached 6.0 cm. RESULTS: The maximum potential rupture rate (actual rupture rate plus elective surgery rate) for small AAAs (3.0 to 4.4 cm) was 2.1% per year, which is less than most reported operative mortality rates. The equivalent rate for aneurysms of 4.5 to 5.9 cm was 10.2% per year. The actual rupture rate for aneurysms up to 5.9 cm using our criteria for surgery was 0.8% per year CONCLUSION: In centers with an operative mortality rate of greater than 2%, (1) surgical intervention is not indicated for asymptomatic AAAs of less than 4.5 cm in diameter, and (2) elective surgery should be considered only for patients with aneurysms between 4.5 and 6 cm in diameter that are expanding by more than 1 cm per year or for patients in whom symptoms develop. In centers with elective mortality rates of greater than 10% for abdominal aortic aneurysm (AAA) repair, the benefit to the patient of any surgical intervention for an asymptomatic AAA of less than 6.0 cm in diameter is questionable.

Aged↗
PubMed1998

Efficacy of a mouthrinse containing 0.05% cetylpyridinium chloride for the control of plaque and gingivitis: a 6-month clinical study in adults.

The objective of this 6-month, double-blind, clinical study, conducted following the American Dental Association (ADA) guidelines, was to provide an assessment of the effectiveness of a newly developed mouthrinse containing 0.05% cetylpyridinium chloride (CPC) for the control of supragingival dental plaque and gingivitis. Adult men and women from the Manchester, England, area were entered in the study, and stratified into two treatment groups (CPC mouthrinse and control mouthrinse), which were balanced for baseline Quigley-Hein Plaque Index scores and baseline Löe-Silness Gingival Index scores. Participants were given an oral prophylaxis and instructed to brush their teeth twice daily (morning and evening) for 1 minute with a soft-bristled toothbrush and fluoride dentifrice provided, immediately followed by rinsing for 30 seconds with 15 cc of their assigned mouthrinse. Examinations for supragingival plaque and gingivitis were conducted after 3 months' and again after 6 months' participation in the study. One hundred eleven participants complied with the protocol and completed the entire 6-month clinical study. At both the 3- and 6-month study examinations, the CPC mouthrinse group exhibited statistically significantly less supragingival plaque and gingivitis than did the control mouthrinse group. At the 6-month examination, the magnitude of these differences met or exceeded 24% for all 4 parameters measured (28.2% for Quigley-Hein Plaque Index, 63.4% for Plaque Severity Index, 24.0% for Löe-Silness Gingival Index, and 66.9% for Gingivitis Severity Index). The magnitude of the reductions in supragingival plaque and gingivitis were adequately large to support a claim of efficacy, in accordance with the criteria provided by the published guidelines of the ADA for the demonstration of the efficacy of a chemotherapeutic agent for the control of supragingival plaque and gingivitis. Thus, the results of this 6-month clinical study support the conclusion that a newly developed mouthrinse containing 0.05% cetylpyridinium chloride provides a statistically significant, clinically relevant level of efficacy for the control of supragingival plaque, and for the control of gingivitis, in accordance with the criteria provided by current ADA guidelines.

Adolescent↗
PubMed1997

Management of chylothorax.

BACKGROUND: Chylothorax is a rare primary or secondary condition the optimum management of which remains uncertain. METHODS: Twenty cases of chylothorax, including ten of primary chylothorax and ten secondary to either malignancy, subclavian vein thrombosis or lymphangioma treated between 1956 and 1986 have been reviewed. RESULTS: Open pleurectomy was the most successful treatment in preventing reaccumulation of the effusion. Three patients had thoracic duct-azygous vein anastomoses, but all anastomoses were probably occluded within a year of surgery. Three patients have been lost to follow-up and five died within 2 years of their treatment, but 12 patients were alive and free from an effusion 3-22 years after treatment. CONCLUSION: Patients with chylothorax should undergo lymphangiography to identify the cause and site of the lymphatic abnormality. Conservative treatment is successful in some patients but should be abandoned if the fluid loss exceeds 1.5 l/day for more than 5-7 days in an adult or more than 100 ml/day in a child. Parietal pleurectomy is the most successful treatment when no distinct chylous leak can be identified. Less commonly, an isolated chylous leak either in the chest or in the abdomen may be identified and this should be treated by direct ligation.

Adult↗
PubMed1996

Continuous monitoring of cellular nitric oxide generation by spin trapping with an iron-dithiocarbamate complex.

Nitric oxide (NO) generation in murine macrophages was determined in real time using the electron paramagnetic resonance (EPR) spin trapping method. An iron complex of N-methyl D-glucamine dithiocarbamate was utilized as the spin trap. This spin trapping compound reacts with NO in solution to form a specific room-temperature stable, mononitrosyl complex which is readily detected and identified by EPR spectroscopy. Mouse peritoneal macrophages were placed in an EPR sample-cell and activated by lipopolysaccharide and gamma-interferon at 37 degrees C, followed by an additional incubation in oxygenated medium without these activation agents. After various incubation periods, spin trap solution was infused to replace the medium in the sample-cell, and the time-evolution of the EPR signal of the spin adduct (NO-complex) was recorded. Rates of NO generation were calculated based upon the initial slopes of the increase in the EPR intensity with time. In comparison to the NO (or NO2-) generation rate obtained under similar experimental conditions using the Griess reaction assay, the spin trapping method was found to be more sensitive, with a lowest limit of the detection of 3 pmol/min. In addition, by using the spin trapping method, NO generation from the same cells could be measured consecutively during various stages of activation, because infusion of the spin trap solution did not affect the viability of macrophages.

Animals↗
PubMed1995

Effect of utilization review in a fee-for-service health insurance plan.

BACKGROUND: Although utilization review is widely used to control health care costs, its effect on patterns of health care is uncertain. METHODS: In 1989, New York City and its unions temporarily replaced actual utilization review with sham review for half the participants in the city's fee-for-service health insurance plan. We compared the health services provided to 3702 enrollees whose requests were subjected to utilization review (the review group) with the services provided to 3743 enrollees whose requests received sham review and were automatically approved for insurance coverage (the nonreview group). The enrollees, physicians, and hospitals were all unaware of the group assignments. RESULTS: During the study period (mean duration, eight months), the members of the review group underwent 1255 procedures in 20 categories of procedures for which second opinions were required (such as breast, cataract, foot, hernia, and hip-replacement surgery, as well as hysterectomy and coronary bypass surgery), and the members of the nonreview group underwent 1365 procedures (P = 0.02). The members of the review group had 124 fewer procedures in doctors' offices and hospital outpatient departments (P = 0.002). In the following year, the members of the review group underwent 248 procedures from the 20 categories, and the members of the nonreview group underwent 234 (P = 0.46). No other differences in patterns of care were found between the groups, including rates of hospital admission to medical-surgical, substances-abuse, or psychiatric units; average lengths of hospital stay; the percentage of enrollees who received preadmission testing; or rates of use of home care. During the study period, the mean age-adjusted insurance payments per person were $7,355 in the review group and $6,858 in the nonreview group (P = 0.06). CONCLUSIONS: The utilization-review program reduced the performance of diagnostic and surgical procedures for which second opinions were required and did not merely delay them until the following year. Otherwise, the program had little effect. Alternatively, actual review and sham review may both have decreased the use of hospital services, with patients or their physicians choosing more efficient treatment when they believed that care would be reviewed.

Case Management↗
PubMed1994

Surgical workload as a consequence of screening for abdominal aortic aneurysm.

A study was performed to evaluate the surgical workload that has resulted from screening an at-risk population for abdominal aortic aneurysm (AAA) and to forecast the likely workload from an established screening programme. Over an 8-year period 8944 people aged 65-80 years were screened; 356 were found to have an AAA of 3 cm or greater in diameter. There were 288 outpatient consultations involving 171 patients, and 43 patients (4.8 per 1000 screened) had surgery during the study period. A fully operational screening programme for a population of 250,000, screening men and women at a rate of 2000 per year, would be expected to produce a surgical workload of nine or ten operations for AAA per year. Screening men only would increase this to 34 annually.

Aged↗
PubMed1994

Catechol adrenergic agents enhance hydroxyl radical generation in xanthine oxidase systems containing ferritin: implications for ischemia/reperfusion.

Iron chelators have been reported to protect tissues against reperfusion injury. This implies that iron is being released into the plasma or is made accessible in tissues for oxidation-reduction reactions. It has been postulated that ferritin is a likely source for this iron. This report demonstrates that adrenergic agents with the catechol structure, which includes the endogenous catecholamines norepinephrine and epinephrine, are capable of releasing iron from ferritin. It is shown that the net release of iron from ferritin by epinephrine is significantly enhanced under anaerobic conditions. The findings suggest that catecholamines can mediate iron release from ferritin under conditions that can occur during ischemia/reperfusion. Catecholamines are also shown to interact with the released iron and xanthine oxidase to produce highly reactive hydroxyl radicals. The implications of this interaction for ischemia/reperfusion are discussed.

Aerobiosis↗
PubMed1993

Neuropsychiatric disorders and periodontal disease.

The purpose of this study was to compare the severity of periodontal disease among subjects with neuropsychiatric disorders with that of a control group of normal subjects in order to determine the association between emotional disturbances and periodontal disease. One hundred and sixty-three subjects hospitalized for neuropsychiatric conditions (NP) and 78 control subjects with no emotional problems were examined. Periodontal attachment loss was measured using Russell's index (PI), and the oral hygiene status was evaluated with the Oral Hygiene Index (OHI) of Green and Vermillion by a single examiner. Full mouth radiographs were also evaluated. The results showed that mean PI, debris, calculus, and OHI scores were generally higher in NP subjects compared to controls. When the effects of severity of debris, calculus, and OHI scores, and daily tooth brushing frequency were controlled, NP subjects had statistically significantly higher mean PI scores than controls. These findings suggest that emotional problems may be associated with the severity of periodontal disease.

Adult↗
PubMed1992

Aetiology and treatment of chylous ascites.

A series of 45 patients with chylous ascites has been reviewed. The age at presentation ranged from 1 to 80 (median 12) years; 23 patients were aged < or = 15 years. Thirty-five patients had an abnormality of the lymphatics (primary chylous ascites); in the remaining ten, the ascites was secondary to other conditions, principally non-Hodgkin's lymphoma (six patients). Two principal mechanisms of ascites formation were identified using lymphangiography and inspection at laparotomy: leakage from retroperitoneal megalymphatics, usually through a visible lymphoperitoneal fistula (14 patients); and leakage from dilated subserosal lymphatics of the small intestine, invariably associated with leaking lacteals causing protein-losing enteropathy (24 patients). Both sites of leakage were present in a further five patients. In the remaining two patients, chyle was leaking from normal mesenteric lymphatics, in one via a ruptured mesenteric lymph cyst and in the other from the site of a previous lymph node biopsy. Other associated lymphatic abnormalities were present in 36 patients, lymphoedema of the leg being the commonest (26 patients). All patients were initially treated conservatively with dietary manipulation; this was the most satisfactory treatment for those with leaking small bowel lymphatics. Surgery (fistula closure, bowel resection or insertion of a peritoneovenous shunt) was performed in 30 patients. Closure of a retroperitoneal fistula, when present, was the most successful operation, curing seven of the 12 patients so treated.

Adolescent↗
PubMed1992

Intra-arterial thrombolysis should be the initial treatment of the acutely ischaemic lower limb.

We review and discuss the initial management of acute arterial occlusion. Thrombolytic therapy has been available for over 25 years but has failed to gain universal acceptance in the initial management of this condition. Support for the use of initial thrombolytic therapy in all patients is based on the following arguments. It may be difficult to distinguish clinically between an embolic or a thrombotic occlusion, and inappropriate surgery in the latter may have disastrous consequences. Therefore, arteriography should be performed in all patients. It is then easy to place a catheter for thrombolytic therapy. This therapy allows treatment of associated medical problems before definitive surgery, and it may enable a more accurate assessment of the obstruction and better planning of surgery after dissolution of some of the occluding thrombus. Recanalisation may make reconstructive surgery easier and, finally, the results with initial thrombolysis are better than with surgery alone. The case against the motion is that expeditious surgery is in the patient's best interest, particularly in embolus, and when there is ischaemic damage to the limb. Furthermore, the reports of thrombolysis currently available are uncontrolled and do not demonstrate convincingly that the results of thrombolytic therapy are superior to surgery alone.

Acute Disease↗
PubMed1991

Non-invasive Doppler-derived cardiac output: a validation study comparing this technique with thermodilution and Fick methods.

The high mortality and morbidity related to cardiac events remains a considerable problem in vascular surgery. Predicting high risk patients is difficult except perhaps by coronary angiography which is invasive, costly and impractical. It would be useful to have a technique which could easily measure cardiac output and stratify cardiac risk in patients needing vascular surgery. Doppler-derived cardiac output may be such a technique. It offers considerable advantages over Swan-Ganz thermodilution measurement in that it is non-invasive, continuous, inexpensive, and requires only limited technical skill and training. In order to assess and validate a Doppler cardiac output monitor (ACCUCOM 2, Datascope Medical Co. Ltd.), we undertook a prospective study comparing Doppler-derived measurements with those obtained by thermodilution and Fick methods. Twelve patients undergoing elective coronary angiography were studied. Swan-Ganz thermodilution catheters were inserted on completion of cardiac catheterisation and five consecutive thermodilution and Doppler measurements made in each patient. Oxygen saturation from pulmonary artery and aortic blood samples, and a single indirect Fick cardiac output, were calculated. Linear regression analysis for Doppler against thermodilution gave a correlation co-efficient (r) of 0.81 (p less than 0.002), and (r) for Doppler against the Fick method was 0.76 (p less than 0.02). Bland and Altman's statistical method showed the differences to be normally distributed. The mean difference (thermodilution minus Doppler) was 0.32 l/min SD 0.48 l/min, 95% confidence limits -0.64 to +1.28 l/min. Doppler-derived cardiac output compares well with traditional methods of measurement and may be a useful tool in the assessment and monitoring of the high risk vascular patient.

Adult↗
PubMed1989

Effects of cigarette smoke, carbon monoxide and nicotine on the uptake of fibrinogen by the canine arterial wall.

An animal model has been used to investigate the effects of cigarette smoke, carbon monoxide and nicotine on the uptake of 125I-labelled fibrinogen by the arterial wall. The uptake of fibrinogen in the smoking group (5.5 +/- 2.8 counts.cm-2 x 10(-4)) and carbon monoxide group (6.1 +/- 2.7 counts.cm-2 x 10(-4)) was greater than the uptake in the control group (4.5 +/- 1.4 counts.cm-2 x 10(-4)) but this difference was not significant. In the nicotine group, there was a highly significant increase in wall uptake of 125I-fibrinogen (9.1 +/- 2.1 counts.cm-2 x 10(-4)) (P less than or equal to 0.001). These results suggest that nicotine, a major constituent of cigarette smoke, increases the retention of 125I-fibrinogen by the arterial wall and that this might be one mechanism by which cigarette smoking exerts its atherogenic effect.

Animals↗
PubMed1988

The effect of cigarette smoke, nicotine, and carbon monoxide on the permeability of the arterial wall.

The association between cigarette smoking and the development of atherosclerosis is well established, but the mechanism that makes cigarettes such a potent "risk factor" is not understood. There is normally a constant insudation of plasma macromolecules into the arterial wall. Fibrinogen and lipids are two of the large molecules involved in atherosclerosis. Therefore we studied the effect of cigarette smoke, nicotine, and carbon monoxide on the permeability of the canine arterial wall to 125I-labeled fibrinogen. The results show that inhaled cigarette smoke significantly and rapidly increases the permeability of the arterial wall to fibrinogen and that this effect can be produced with carbon monoxide alone but not with intravenous nicotine.

Animals↗
PubMed1986

Stapled ileo-anal anastomosis: a technique to avoid mucosal proctectomy in the ileal pouch operation.

Ten patients have undergone abdominal proctocolectomy with the formation of an ileal reservoir anastomosed onto the anal canal using a stapling device. This technique avoids stripping of the rectal mucosa from the muscle tube (mucosal proctectomy) which is time consuming and often difficult. One patient is awaiting closure of her ileostomy. The remaining seven are continent and are passing between one and six motions a day.

Adult↗