Biomedical subjects

J C Lynch

Publications and source records attributed to J C Lynch.

At least 55 records · Page 3Linked to original sources

PubMed1993

Epidemiology of low cholesterol levels in older adults. The Cardiovascular Health Study.

BACKGROUND: Low cholesterol levels have been associated with increased mortality from stroke, cancer, and other noncardiovascular diseases, but the reasons for this association remain unclear. One explanation is that persons with low cholesterol levels have early or occult disease that eventually leads to their deaths. METHODS AND RESULTS: This possibility was explored in 2,091 men and 2,714 women 65-100 years old in the Cardiovascular Health Study, a multicenter observational study of risk factors for heart disease and stroke in older adults. Cholesterol levels < or = 160 mg/dL were present in 11.6% of men and 3.7% of women and increased in prevalence with age. After adjustment for age, total cholesterol levels in this range were associated with a twofold increased prevalence of treated diabetes in men and women and with a twofold increased prevalence of cancer diagnosed in the preceding 5 years in women only. Low cholesterol was also associated with lower levels of hemoglobin, albumin, and factor VII, suggesting a link with hepatic synthetic function. On multivariate analysis, factors most strongly associated with low cholesterol levels in men and women were decreased factor VII levels, decreased albumin, and diabetes. CONCLUSIONS: Cross-sectional associations with low cholesterol levels differ by sex and suggest poorer health by some measures. The observed relations with treated diabetes and impaired hepatic synthetic function should be examined for risk of mortality in longitudinal data from this and other observational studies.

Aged↗

PubMed1993

Survival following mechanical ventilation for acute respiratory failure in adult men.

STUDY DESIGN: Survival following mechanical ventilation for acute respiratory failure has important implications for medical decision-making and allocation of expensive resources for critical care. PROCEDURE: We reviewed a 5-year experience with mechanical ventilation in 383 men with acute respiratory failure and studied the impact of patient age, cause of acute respiratory failure, and duration of mechanical ventilation on survival. Survival rates were 66.6 percent to weaning, 61.1 percent to ICU discharge, 49.6 percent to hospital discharge, and 30.1 percent to 1 year after hospital discharge. When our data were combined with 10 previously reported series, mean survival rates were calculated to be 62 percent to ventilator weaning, 46 percent to ICU discharge, 43 percent to hospital discharge, and 30 percent to 1 year after discharge. Of 255 patients weaned from mechanical ventilation, 44 (17.3 percent) required an additional period of mechanical ventilation during the same hospitalization. RESULTS: Age had a significant influence on survival to hospital discharge and on that to 1 year after hospital discharge, and the cause of acute respiratory failure had a significant influence on survival only to weaning. Survival was best in younger patients and those with COPD or postoperative respiratory failure and worst in patients resuscitated after cardiac or respiratory arrest. Increased duration of mechanical ventilation significantly reduced survival only to hospital discharge. Overall survival was significantly affected by age and cause of acute respiratory failure, but not by duration of mechanical ventilation. CONCLUSION: We conclude that age, cause of acute respiratory failure, and duration of mechanical ventilation have specific influences on the generally poor outcome of mechanical ventilation for acute respiratory failure.

Acute Disease↗

PubMed1993

[Lipomyelomeningocele: experience with 16 operated cases].

Sixteen patients with lipomyelomeningoceles were operated by microsurgery technics from 1980 to 1991. Patients with lipomyelomeningoceles inappropriately treated or not submitted to treatment will develop significant neurological sequelae. In the authors' opinion, proper management of the patient with spinal lipoma requires early prophylactic resection of the lipoma and untethering of the spinal cord.

Adolescent↗

PubMed1992

Saccade initiation and latency deficits after combined lesions of the frontal and posterior eye fields in monkeys.

1. Monkeys were trained to perform horizontal visually guided saccades. Latency was measured before and after bilateral lesions of the frontal eye field (FEF) and after combined lesions of both the FEF and the posterior eye field. Destruction of either of these regions alone causes only modest deficits of eye movement, but destruction of both together produces profound oculomotor impairment. The results support the proposal that purposeful eye movements are controlled by a distributed corticocortical network that includes nodes in frontal and parieto-occipital regions.

Animals↗

PubMed1992

[Multiple intracranial aneurysms].

Thirty eight patients with multiple intracranial aneurysms were studied. They correspond to 19.4% of all aneurysms treated over a twelve year period in the Servidores do Estado Hospital. 89 aneurysms and 4 infundibuli were detected. In 71.0% of the patients, two aneurysms were found; in 18.4%, three aneurysms; and in 10.4%, 4 or 5 aneurysms were observed. Twenty-seven patients were women and 11 men, ranging in age from 16 to 72 (average 47 years old). Subarachnoid hemorrhage was found in 36 patients (86.8%). The operative mortality in this series was 3.5%. We concluded that patients with multiple intracranial aneurysms should have all aneurysms, that can bleed, clipped through standard micro-neurosurgery technics.

Adolescent↗

PubMed1991

Intravascular plastic catheters. How they potentiate tumor necrosis factor release and exacerbate complications associated with sepsis.

We tested the hypothesis that long-term intravascular cannulation exacerbates the harmful effects of an infectious challenge. Four groups of rats were initially studied: rats without intravascular catheters or infection (group 1), rats without catheters with a polymicrobial infection (group 2), rats with catheters but no infection (group 3), and rats with catheters and infection (group 4). Infected animals had an increased mortality and generated a significantly increased tumor necrosis factor response compared with noninfected animals. Animals with catheters and infection generated far less cardiac output than animals from the other three groups. No histologic changes differentiated the four groups. Therefore, the presence of a sterile intravascular catheter significantly increases cardiac dysfunction and mortality rates in rats with chronic bacteremia. These results suggest that intravascular plastic catheters potentiate the destructive cascade of events produced by the host in response to bacteremia.

Abscess↗

PubMed1991

Mediastinal bulk in Hodgkin disease. Method of measurement versus prognosis.

The presence of a large mediastinal mass (bulk disease) in patients with newly diagnosed Hodgkin disease is believed by many to predict a poorer prognosis and to warrant more aggressive treatment. These masses are formed by an aggregate of mediastinal lymph nodes. The determination of bulk disease is confusing, with at least 27 definitions having been proposed. This study seeks to determine the best definition, and determine the role of thoracic computed tomography (CT) versus chest radiographs in the evaluation of mediastinal bulk disease. One hundred seven consecutive newly diagnosed adult patients with Hodgkin disease were evaluated using 13 commonly used definitions of mediastinal bulk. Of the 76 patients with mediastinal disease, 73 had bulk disease as defined by at least one definition. Of the 16 patients who had recurrence of mediastinal disease, only the presence of bulk disease according to one definition (hilar adenopathy, greater than or equal to 2 cm) was statistically significant in its prediction (P = .05). No definition based on the size of the mediastinal nodal mass reliably predicted those patients with recurrence. No differences in our data were found for differing stages or disease cell types, the presence of extension, or with differing treatment regimens. This study highlights the confusion and controversy surrounding the use of bulk disease of the mediastinum as an adverse prognostic indicator. The numerous methods of measuring mediastinal bulk in patients with newly diagnosed Hodgkin disease are confusing, overlap, and are not statistically reliable in predicting recurrence. Efforts to create a standard or ideal definition were unsuccessful. Thoracic CT was useful in those patients whose bulk disease distorted only one side of the mediastinal silhouette on chest radiographs.

Adult↗

PubMed1991

Reported practice behaviors for medical care of patients with diabetes mellitus by primary-care physicians in Pennsylvania.

OBJECTIVE: To compare the American Diabetes Association standards for the medical care of diabetic patients with reported care patterns. RESEARCH DESIGN AND METHODS: These standards were compared with reported care patterns obtained from a stratified random telephone survey of general practitioners, family physicians, and general internists in Pennsylvania. A total of 610 physicians completed the survey for a response rate of 73%. RESULTS: All primary-care physicians reported measurement of glycosylated hemoglobin, routine referrals to eye doctors, and patient self-monitoring of blood glucose less than recommended. Nearly all physicians performed foot exams, but the exams were infrequent for many of the physicians. Significant and independent differences (P less than 0.05) were noted between different groups of physicians. Older physicians and general practitioners reported patterns of care most different from the recommended standards for referral to eye doctors, measurement of glycosylated hemoglobin, and use of patient self-monitoring of blood glucose. General practitioners reported the lowest frequency of foot exams. CONCLUSIONS: Educational programs on diabetes for primary-care physicians should focus on reported behaviors most different from recommended standards and may need to target subgroups of physicians to achieve a more uniform level of care for all diabetic patients.

Blood Glucose Self-Monitoring↗

PubMed1990

[Chronic subdural hematoma: surgical treatment and results in 96 patients].

Ninety-six patients with chronic subdural hematoma were treated surgically and their clinical features presented in detail. Carotid angiography gave the correct diagnosis in all patients. CT scan was performed in 38 and was diagnostic in 92.1% of the cases. The clots were removed through burr-holes or small trephines: 78 (81.3%) patients were cured, 6 (6.2%) had permanent disabilities and 12 (12.5%) died. Operative mortality was related to the degree of neurological impairment, advanced age and systemic diseases. Neurologic sequelae were mostly related to reoperations due to recurrence of the hematoma and bilateral clots, as well. Low intracranial pressure syndrome with brain collapse was seen in 3 cases and treated with lumbar injection of saline solution. The delay in diagnosis and operation as cause of bad outcome is stressed.

Adolescent↗

PubMed1990

The significance of necrotic mediastinal lymph nodes on CT in patients with newly diagnosed Hodgkin disease.

Necrosis in lymph nodes shown on CT in many patients with nodal metastases may indicate that the primary tumor is aggressive and has a high degree of malignancy. However, the significance of nodal necrosis in patients with mediastinal Hodgkin disease remains uncertain. We studied the thoracic CT scans of 76 patients who had newly diagnosed Hodgkin disease with mediastinal involvement with respect to the presence of necrosis (low attenuation, complex, fluidlike areas), the size and volume of the mass, the sites involved, extension ("E" disease), and the patients' clinical response to treatment. CT scans showed necrotic nodes in 16 patients (21%). The difference between these patients and those without necrotic nodes was not statistically significant with respect to sex, age, stage, distribution of disease, presence of E disease, cell type, mass diameter, or the presence of bulk disease (mass diameter/maximal thoracic diameter greater than or equal to 0.33). The mass volume as measured by CT was not significantly (p = .08) larger (1274 cm3) than the group without necrotic nodes (876 cm3). An analysis of the various mediastinal sites involved showed no difference between patients with and without necrotic nodes. Lastly, the presence of necrotic nodes had no significant impact on patients' clinical response to treatment or survival. The presence of mediastinal necrotic nodes appears to have little radiologic or prognostic significance in patients with newly diagnosed Hodgkin disease.

Adult↗

PubMed1990

The effects of sleep loss on cognitive performance of resident physicians.

Although the long hours worked by resident physicians have raised concern in the public, legislators, and members of the medical profession, the consequences of sleep loss on the ability of residents to perform in clinical settings is unknown. The present study examined the effects of various amounts of reported sleep on cognitive performance measured by the American Board of Family Practice in-training examination. A total of 353 family practice residents in 21 programs who took the examination in Pennsylvania in 1988 were studied. Linear regression analysis demonstrated a statistically significant (P less than .05) decline in composite test score with decreasing sleep on the night before the examination for residents in each year of training. Loss of one night's sleep resulted in changes in test scores that were approximately equivalent in magnitude to the change that occurred in test scores between residents in the first and third year of training. The results suggest that prolonged testing over several hours may be necessary to detect the subtle but significant differences in cognitive performance that are present with relatively mild degrees of sleep loss.

Cognition↗

PubMed1989

Deficits of visual attention and saccadic eye movements after lesions of parietooccipital cortex in monkeys.

1. Visual attention is often profoundly disturbed in humans after damage to the cortex of the posterior parietal lobe, particularly of the minor hemisphere, with some patients being totally unaware of visual stimuli in the hemifield of extrapersonal space contralateral to the cortical damage. This severe form of visual inattention is usually called contralateral neglect and has occasionally been reported following posterior parietal lesions in monkeys. However, in monkeys, only qualitative observations have been published and those reports are not in agreement concerning the severity of the deficit. The present experiments were designed to measure quantitatively the amount of disruption of selective visual attention which is produced by lesions of posterior parietal and parietooccipital cortical lesions in monkeys. 2. Five monkeys were trained to visually fixate and follow with their gaze a small visual stimulus as it suddenly moved varying distances (8, 16, or 24 degrees) from the midline into the left or right visual hemifields. Two animals then received a unilateral cortical lesion limited to the inferior parietal lobule (IPL). Three animals received unilateral lesions which included both the inferior parietal lobule and a portion of adjacent dorsal prestriate cortex (IPL-PS). 3. Visual inattention is commonly divided into two levels of severity. The more severe form, contralateral neglect, is the complete absence of behavioral response to a stimulus in the visual field contralateral to hemisphere damage. The less severe deficit, usually called visual extinction, is a tendency to ignore the contralateral of two visual stimuli when they appear simultaneously and symmetrically placed with respect to the center of the subject's surroundings. The five monkeys in this study were tested on a stimulus paradigm which simultaneously measured the severity of visual neglect and also the amount and duration of visual extinction which were produced by the cortical lesions. 4. All monkeys displayed contralateral visual extinction after unilateral posterior parietal or parietooccipital lesions. Three of the five monkeys showed a reversal of the visual extinction after a second, symmetrical lesion was placed in the opposite hemisphere. No monkey showed evidence of full-blown contralateral neglect after lesions limited to the parietooccipital cortex, either in the formal testing situation or during informal neurological examinations. The severity of the observed inattention did not appear to be related to the size of the cortical lesions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

[Primary hematoma of the brain stem: considerations apropos of a case].

The case of a 48 year-old woman presenting with a primary pontine hematoma is reported. The clinical evolution simulated a brain stem tumor and the diagnosis of hematoma was not established before the operation. The preoperative neurological deficit improved except for a facial nerve palsy. These hematomas are thought to be due to rupture of "cryptic" arteriovenous malformations and should be differentiated from those secondary to systemic hypertension. The diagnosis of brain stem hematomas should be considered in any case of brain stem lesion, especially in young and normotensive patients.

Cerebral Hemorrhage↗

PubMed1988

[Xanthogranuloma of the choroid plexus: a case report].

We report an unusual case of a 30-year-old man who presented blindness and raised intracranial pressure secondary to a huge lateral ventricle xanthogranuloma. Computed tomographic scanning showed a highly calcified hyperdense mass that did not enhance after contrast administration. The mass was subtotally resected via transcallosal approach. The pathogenesis of the choroid plexus xanthogranuloma is discussed.

Adult↗

PubMed1987

Frontal eye field lesions in monkeys disrupt visual pursuit.

Discussions of the cortical control of eye movement have generally attributed the generation of saccadic movements to the frontal eye fields (FEF) and the control of pursuit movements to posterior parietal or prestriate cortex. Monkeys were trained to perform a series of oculomotor tasks, including both saccade and pursuit paradigms. Surgical ablation of the frontal eye fields produced only minor disruption of saccade performance, but caused a dramatic deficit in the ability of monkeys to visually track a slowly moving target. This disorder has not previously been associated with FEF lesions. These results necessitate a major re-evaluation of the way in which the cerebral cortex participates in oculomotor control.

Animals↗

PubMed1985

The differential projection of two cytoarchitectonic subregions of the inferior parietal lobule of macaque upon the deep layers of the superior colliculus.

Parietotectal projections were studied in the macaque monkey in experiments designed to compare the distribution of fibers originating in two cytoarchitecturally distinct regions within the inferior parietal lobule: the inferior bank of the intraparietal sulcus (area POa of Seltzer and Pandya, '80) and the adjoining part of area PG (von Bonin and Bailey, '47) on the convexity of the hemisphere, here called PGc. A dense fiber projection from POa to the intermediate and deep layers of the superior colliculus was observed by both anterograde autoradiographic and anterograde horseradish peroxidase methods. In contrast, only faint labeling was seen in the superior colliculus following injections of tritiated amino acids into area PGc on the convexity. In a second set of experiments, injections of horseradish peroxidase were placed in the intermediate and deep layers of the superior colliculus so that the cells of origin of the parietotectal projections could be identified. Many retrogradely labeled neurons were observed in POa, whereas very few labeled neurons were present in any other subdivision of the inferior parietal lobule or in the superior parietal lobule. These findings demonstrate that area POa has a prominent direct efferent projection to a major premotor region of the brainstem oculomotor system and suggest that by virtue of its parietotectal connection, this sulcal subdivision may have functional properties not shared with other subdivisions of the inferior parietal lobule.

Animals↗

PubMed1985

[Hypertensive intracerebral hematomas: apropos of 50 cases].

Fifty cases of supratentorial intracerebral hematomas associated with hypertension are analyzed. The best treatment of the intracerebral hematomas is not settled. The authors reviewed and analyzed the literature and they suggest that the small hematomas should be managed conservatively as well as those patients in deep coma. The subcortical hematomas usually improve with surgical removal. In the deep ganglionic type the initial treatment is clinical. If no improvement occurs the hematoma should be removed with microsurgery technique.

Adult↗

PubMed1985

[Redundant lumbar nerve root syndrome: report of a case].

The redundant nerve roots syndrome is the association of high grade extradural lumbar spinal block with a tortuous elongated nerve roots depicted as multiple serpentiginous filling defects on myelography. A case of a 64-years-old man is presented. Laminectomy and facetectomy were done with great improvement of the symptoms. A discussion of this syndrome is presented.

Humans↗