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J C Lynch

Publications and source records attributed to J C Lynch.

At least 37 records · Page 2Linked to original sources
PubMed1998

Organization of the medial pulvinar nucleus in the macaque.

BACKGROUND: The medial pulvinar appears to subserve the integration of associative cortical information and projects to visuomotor-related cortex. In contrast to the other pulvinar subdivisions, the medial pulvinar is a polymodal structure. Therefore, we studied the structural organization of the medial pulvinar to determine how it differs from the surrounding unimodal nuclei. METHODS: Nissl-stained sections were examined to determine the boundaries of, and the distribution of neuronal sizes within, the medial pulvinar. In addition, Golgi-impregnated neurons were examined and drawn for analysis. Only rhesus monkey specimens were used, and the material had been prepared previously for other studies. RESULTS: Projection neurons have round to oval somata and moderate numbers of primary dendrites that extend for short distances before branching into many secondary branches. Two variations of projection neurons (P1 and P2) were distinguished on the basis of the diameters of their dendritic tree. Both varieties have short dendrites that radiate in all directions. They differ in that P2 cells have longer second tier dendrites than P1 cells. Three types of local circuit neurons, tufted, radiating and varicose, were distinguished on the basis of their dendritic morphology. Four types of afferent fibers were identified. Type 1 afferents form cone-shape terminal arbors. Type 2 afferents are similar to those reported for retinal or cortical terminals. Type 3 afferents are of medium thickness and of an unknown origin. Type 4 afferents are thin and have small varicosities consistent with previously described cortical afferents. Afferent fibers are predominantly oriented along the mediolateral axis of the nucleus. We observed putative contacts between some afferents and local circuit neurons and between local circuit neurons and projection neurons. CONCLUSIONS: Medial pulvinar neurons are generally smaller and rounder than those found in the adjacent pulvinar nuclei. These results provide additional evidence for structural distinctions between thalamic nuclei having different functions. However, the observed differences are subtle. In addition, the data in this report provide morphological evidence that cortical signals are likely to be integrated by means of the circuitry located within the nucleus.

Animals↗
PubMed1998

Effect of follicularity on autologous transplantation for large-cell non-Hodgkin's lymphoma.

PURPOSE: This study evaluated the outcomes of patients who received high-dose chemotherapy (HDC) and autologous hematopoietic stem-cell transplantation (ASCT) for large-cell non-Hodgkin's lymphoma (NHL) and the effect of a follicular versus a diffuse histology. PATIENTS AND METHODS: The prognostic factors in 289 patients who underwent HDC and ASCT for large-cell NHL between May 1983 and December 1996 were analyzed. RESULTS: With a median follow-up duration of 24 months for surviving patients (range, 3 to 131 months), 112 of 289 (39%) were alive and 82 of 289 (28%) were failure-free. In a multivariate analysis, the factors associated with a poorer failure-free survival (FFS) included a lactic dehydrogenase (LDH) level greater than normal (P < .0001), three or more prior chemotherapy regimens received (P < .01), a mass > or = 10 cm at transplant (P < .01), and diffuse histology at the time of transplant (P = .026). Patients who received HDC and ASCT for large-cell NHL in the good-prognosis category (normal LDH, < three prior chemotherapy regimens, no large mass, and not chemotherapy-resistant) had a 5-year survival rate of 45%. Within the good-prognosis group, patients with diffuse large-cell NHL had a 5-year survival rate of 42% compared with 58% for patients with follicular large-cell (FLC) lymphoma (P = .05). CONCLUSION: Good-prognosis patients with FLC histology who receive HDC and ASCT have an improved survival compared with good-prognosis patients with a diffuse large-cell histology.

Adolescent↗
PubMed1998

Outcome of 337 intracranial aneurysms patients operated in a public hospital.

Many recent series of surgery for intracranial aneurysms have been based on experience of developed countries with great resources and a state of art health care. The purpose of the current study is to correlate the outcome of patients operated for intracranial aneurysms, reported from intensive high technology neurosurgical centers with the results of low technology, environment, where we practice. Between January 1986 and December 1996, 337 patients with intracranial aneurysms were operated on at the Servidores do Estado Hospital. We retrospectively reviewed the medical and radiologic records and compared the outcome of this group with other series derived from developed countries. The overall mortality of this series was 6.9%. Of the 313 good grades surgical patients, the mortality was 4.7% and the successful results were obtained in 88.8% individuals. We conclude that patients harboring intracranial aneurysms can be satisfactory handled in less developed nations, if a meticulous intraoperative technique is employed, even though sophisticated technology and equipment are not available.

Adolescent↗
PubMed1997

Subcortical input to the smooth and saccadic eye movement subregions of the frontal eye field in Cebus monkey.

We have recently identified two functional subregions in the frontal eye field (FEF) of the Cebus monkey, a smooth eye movement subregion (FEFsem) and a saccadic subregion (FEFsac). The thalamic input to these two subregions was studied and quantified to gain more information about the influence of the cerebellum and basal ganglia on the oculomotor control mechanisms of the cerebral cortex. A recent study using transneuronal transport of virus demonstrated that there are neurons in the basal ganglia and cerebellum that project to the FEFsac with only a single intervening synapse (Lunch et al., 1994). In the present study, we concentrated on the thalamic input to the FEFsem to define possible basal ganglia-thalamus-cortex and cerebellum-thalamus-cortex channels of information flow to the FEFsem. We localized the functional subregions using low threshold microstimulation, and retrogradely transported fluorescent tracers were then placed into the FEFsem and FEFsac. The neurons that project to the FEFsem are distributed in (1) the rostral portion of the ventral lateral nucleus, pars caudalis, (2) the caudal portion of the ventral lateral nucleus, pars caudalis, (3) the mediodorsal nucleus, (4) the ventral anterior nucleus, pars parvocellularis, and (5) the ventral anterior nucleus, pars magnocellularis. In contrast, the large majority of neurons that project to the FEFsac are located in the paralaminar region of the mediodorsal nucleus. The FEFsac and FEFsem thus each receive neural input from both basal ganglia-receiving and cerebellar-receiving cell groups in the thalamus, but each receives input from a unique combination of thalamic nuclei.

Animals↗
PubMed1997

Diabetes mellitus and echocardiographic left ventricular function in free-living elderly men and women: The Cardiovascular Health Study.

This report describes the relation among diabetes, blood pressure, and prevalent cardiovascular disease, and echocardiographically measured left ventricular mass and filling (transmitral valve flow) velocities in the Cardiovascular Health Study, a cohort of 5201 men and women > or = 65 years of age. Ventricular septal and left posterior wall thicknesses were greater in diabetic than in nondiabetic subjects, showing a significant linear trend (p = 0.025 for ventricular septal thickness in both sexes combined, p = 0.002 for posterior wall thickness) with increased duration of diabetes. Increased wall thickness of the ventricular septum or the left posterior wall was not associated with prevalent coronary heart disease (CHD) in the cohort. Increased left ventricular mass was associated with diabetic persons not reporting CHD and with all subjects with CHD regardless of glucose tolerance status. After adjusting for body weight, blood pressure, heart rate, and prevalent coronary or cerebrovascular disease, diabetes (as measured by glucose level, insulin use, oral hypoglycemic use, and a positive history of diabetes before baseline examination) remained an independent predictor of increased left ventricular mass among men and women (174.2 gm in diabetic men vs 169.8 gm in normal men, 138.2 gm in diabetic women vs 134.0 gm in normal women, p = 0.043 for both sexes combined). Both early and late diastolic transmitral peak flow velocities were higher with increased duration of diabetes, but the calculated ratio of the early peak flow velocity to the late velocity (E/A ratio) did not differ significantly between subjects with historical diabetes and those with normal fasting glucose (both genders combined, p = 0.190). Glucose level, insulin use, oral hypoglycemic use, and a positive history of diabetes before baseline examination were significant independent predictors of the late transmitral peak flow velocity and its integrated flow-velocity curve but not for the integral of the early peak flow velocity or the E/A ratio. Diabetes is associated with abnormal left ventricular structure and function in elderly persons. This association persists after adjustment for body weight, blood pressure, heart rate, and reported coronary or cerebrovascular disease.

Aged↗
PubMed1997

Carrying the burden of cardiovascular risk in old age: associations of weight and weight change with prevalent cardiovascular disease, risk factors, and health status in the Cardiovascular Health Study.

Measured weight in old age, reported weight at age 50 y, and weight change from age 50 y to old age were studied in association with prevalent cardiovascular disease (CVD), CVD risk factors, and health status in a population of 4954 men and women aged > or = 65 y in the Cardiovascular Health Study (CHS). Heavier weight (i.e., generally weight in the fourth quartile for the cohort) at age 50 y was more closely associated with prevalent CVD than was current weight, with these associations stronger in women than in men. Heavier current weight and heavier weight at age 50 y were associated with cardiovascular risk factors, including higher blood pressure, lower high-density-lipoprotein cholesterol, and higher fasting insulin. Heavier weight at both time points was related to mobility problems in both men and women and to lower current physical activity levels; among women, strong associations were also seen with lower education and current income. Remaining within 10% of reported weight at age 50 y was associated with better health status as measured by reported health, mobility difficulty, number of medications, and prevalent CVD in men. Paradoxically, most cardiovascular risk factors were lowest for weight losers despite an association of weight loss with poorer health. In this cohort of persons aged > or = 65 y, heavier weight was associated with CVD and CVD risk factors, suggesting that prevention of overweight may prove beneficial in improving cardiovascular risk in older persons. Weight stability from age 50 y to old age was associated with better health status than was weight gain or loss.

Aged↗
PubMed1996

Functionally defined smooth and saccadic eye movement subregions in the frontal eye field of Cebus monkeys.

1. Intracortical microstimulation was used to localize and define the smooth and saccadic eye movement subregions of the frontal eye field (FEF) and the supplementary eye field (SEF) in nine hemispheres of six Cebus apella monkeys and to map the hand/arm areas in the dorsal premotor area and other adjacent areas in five hemispheres of three C. apella monkeys. Monkeys were anesthetized during experiments with Telazol, a dissociative agent that has no significant effect on microstimulation-induced eye movement parameters (current threshold, velocity, and duration). The functional subregions were defined with the use of low threshold current (< or = 50 microA). Electrically elicited eye movements were videotaped and quantified. The two types of eye movements were clearly distinguished by their significantly different duration and velocity (P < 0.0001) and their different responses to long stimulus trains. 2. The saccadic subregion of the FEF in Cebus monkeys is in the same location as in macaque monkeys (Walker's areas 8a and 45). Most of the functional and anatomic characteristics of the saccadic subregion of Cebus are the same as those reported in the saccadic FEF subregion of macaque monkeys. 3. A subregion in which only smooth eye movements were evoked was found in the posterior shoulder of the superior arcuate sulcus near its medial tip. A band of inexcitable cortex separated the SEF and this smooth eye movement subregion of the FEF. This supports the proposal that the smooth eye movement subregion is independent of the SEF but is analogous to the saccadic subregion of the FEF. The existence of two subregions of the FEF was further confirmed by single-unit recording results. It is proposed that the smooth eye movement subregion in Cebus monkeys may be comparable with the one described in macaque monkeys. 4. Both saccadic and smooth eye movements were also reliably evoked in the SEF in each hemisphere studied. This result strongly indicates that the SEF is concerned with not only saccadic eye movements, as previously reported, but also with smooth (pursuit) eye movements.

Animals↗
PubMed1996

Corticocortical input to the smooth and saccadic eye movement subregions of the frontal eye field in Cebus monkeys.

1. The locations and connections of the smooth and saccadic eye movement subregions of the frontal eye field (FEFsem and FEFsac, respectively) were investigated in seven hemispheres of five Cebus monkeys. The supplementary eye field was also mapped in seven hemispheres and the hand/arm regions of the dorsal and ventral premotor areas were localized in five hemispheres. Monkeys were immobilized during experiments with Telazol, a dissociative anesthetic agent that has no significant effect on microstimulation-induced eye movement parameters (threshold, velocity, and duration). The functional subregions were defined with the use of low threshold intracortical microstimulation (current < or = 50 microA). Then different retrogradely transported fluorescent tracers were placed into these functionally defined regions. 2. The FEFsac in Cebus monkey is in the same location as the one in macaque monkeys, which is in Walker's areas 8a and 45. The FEFsem is located in the posterior shoulder of the superior arcuate sulcus near its medial tip and is therefore more accessible for tracer injections than the one in macaque monkeys. This subregion is within cytoarchitectural area 6a beta, which is distinct from the adjacent area 6a alpha (dorsal premotor area). This smooth eye movement subregion may be comparable with the one in macaque monkeys. 3. Cortical connection patterns of the FEFsac and FEFsem are similar and parallel to each other. The predominant neural input to these two subregions originates in other cortical eye fields, including the supplementary eye field, the parietal eye field, the middle superior temporal area, and the principal sulcus region. These cortical eye fields each contain two separate, almost non-overlapping, distributions of labeled neurons that project to the corresponding frontal eye field (FEF) subregions. These results suggest that there may be similar, but relatively independent, parallel corticocortical networks to control pursuit and saccadic eye movements. The weak connections between the middle temporal area (MT) and FEF suggest that the MT may not provide the major source of visuomotion inputs to the FEF, but that it rather plays a role in mediating visual information that is relayed from the striate and extrastriate cortices via MT to the parietal cortex and then to the FEF. In addition to the well-known neural connections between the lateral intraparietal area and the FEF, additional parietal projections have been demonstrated from the dorsomedial visual area area specifically to the FEFsac and from area 7m specifically to the FEFsem.

Animals↗
PubMed1996

Uterine rupture and scar dehiscence. A five-year survey.

A review of the medical records from two public hospitals in Sydney was undertaken to determine the incidence of this uncommon complication. Twenty-seven cases of uterine rupture were reported out of 31,115 deliveries with an incidence of 0.086% (versus 0.05% in the current literature). The incidence associated with previous caesarean section was 0.038% (versus 0.8% in the current literature). Predisposing and associated factors in this review were similar to those reported by others. There was no maternal mortality in our series but the fetal mortality rate was 5 out of 27 cases. Uterine ruptures in the midtrimester were associated with high rates of maternal morbidity and fetal loss. Forty-eight per cent of patients with uterine rupture received epidural analgesia. The associated factors and outcomes are discussed. The current literature is reviewed in relation to this high-risk group of patients.

Adult↗
PubMed1995

Sex, age, and disease affect echocardiographic left ventricular mass and systolic function in the free-living elderly. The Cardiovascular Health Study.

BACKGROUND: Left ventricular (LV) hypertrophy, as measured by M-mode echocardiography, is an independent predictor of mortality and/or morbidity from coronary heart disease (CHD). LV global and segmental systolic dysfunction also have been associated with myocardial ischemia and cardiovascular morbidity and mortality. Echocardiographic data, especially two-dimensional, have not been available previously from multicenter-based studies of the elderly. This report describes the distribution and relation at baseline of echocardiographic LV mass and global and segmental LV wall motion to age, sex, and clinical disease category in the Cardiovascular Health Study (CHS), a cohort of 5201 men and women (4850 white) 65 years of age and older. METHODS AND RESULTS: M-mode LV mass adjusted for body weight increased modestly with age (P < .0001), increasing less than one gram per year increase in age for both men and women. After adjustment for weight, LV mass was significantly greater in men than in women and in participants with clinical CHD compared with participants with neither clinical heart disease nor hypertension (both P < .001). Across all CHS age subgroups, the difference in weight-adjusted LV mass by sex was greater in magnitude than the difference related to clinical CHD. M-mode measurements of LV mass could not be made in 34% of CHS participants, and this was highly related to age (29% in the 65 to 69 year versus 50% in the 85+ year age group, P < .001) and other risk factors. In participants with clinical CHD and with neither clinical heart disease nor hypertension, LV ejection fraction and segmental wall motion abnormalities were more prevalent in men than women (all P < .001). Of interest, 0.5% of men and 0.4% of women with neither clinical heart disease nor hypertension had LV segmental wall motion abnormalities, suggesting silent disease, compared with 26% of men and 10% of women in the clinical CHD group (P < .0001). Multivariate analyses revealed male sex and presence of clinical CHD (both P < .001) to be independent predictors of LV akinesis or dyskinesis. CONCLUSIONS: Significant baseline relations were detected between differences in sex, prevalent disease status, and echocardiographic measurements of LV mass and systolic function in the CHS cohort. Age was weakly associated with LV mass measurements and LV ejection fraction abnormalities. These relations should be considered in evaluating the preclinical and clinical effects of CHD risk factors in the elderly.

Age Factors↗
PubMed1995

Slow and saccadic eye movements evoked by microstimulation in the supplementary eye field of the cebus monkey.

1. Intracortical microstimulation was used to map the supplementary eye field (SEF) in eight hemispheres of five Cebus apella monkeys. Monkeys were immobilized during experiments with Telazol (tiletamine HCl and zolazepam HCl), a dissociative anesthetic agent that was demonstrated to have no significant effect on microstimulation-induced eye movement parameters compared with similar experiments in alert, behaviorally trained monkeys. The functional subregions were defined with the use of low-threshold current (< or = 50 microA). Electrically elicited eye movements were videotaped and quantified. Both slow and saccadic eye movements were reliably evoked at low threshold by microstimulation in each of eight hemispheres studied. The two types of eye movements were clearly distinguished by their significantly different duration and velocity (P < 0.0001) and their different responses to long stimulus trains. The results strongly support the proposal that the SEF produces not only saccadic eye movements as previously reported but also slow (pursuit) eye movements.

Anesthetics↗
PubMed1995

Physician recommendations for dietary change: their prevalence and impact in a population-based sample.

A random-digit-dialing survey to examine the prevalence, content, and impact of physician dietary recommendations in a representative population-based sample of Washington State residents was administered to 1972 persons aged 18 years and older. Twenty percent of those surveyed received a physician's recommendation for dietary change in the previous year. The most common recommendations were to decrease intake of cholesterol, calories, and red meat and to increase intake of vegetables and fiber. Respondents receiving recommendations were more likely to report decreased use of high-fat foods and increased use of high-fiber foods and to be in the maintenance stage of dietary change. Results suggest that physicians can play a limited role in promoting dietary change.

Adolescent↗
PubMed1994

Input to the primate frontal eye field from the substantia nigra, superior colliculus, and dentate nucleus demonstrated by transneuronal transport.

The purpose of these experiments was to study the subcortical input to the frontal eye field (FEF) and to determine which subcortical structures might project to the FEF via pathways that contain only a single intervening synapse. We used retrograde transneuronal transport of herpes simplex virus type 1 (HSV-1) to label second-order neurons that send information to the FEF of cebus monkeys. The saccade region of the FEF was identified physiologically using intracortical stimulation and then injected with a strain of HSV-1 known to be transported transneuronally in the retrograde direction. Retrograde transport of virus labeled neurons was observed in all the thalamic sites known to innervate the FEF. In addition, we found neurons labeled by transneuronal transport in three subcortical sites: the pars reticulata of the substantia nigra, the optic and intermediate gray layers of the superior colliculus, and a posterior portion of the dentate nucleus of the cerebellum. Each of these sites has been shown in prior studies to project to thalamic regions that innervate the FEF. Moreover, the neurons labeled through transneuronal transport were located in a subregion of each subcortical site that is known to be involved in oculomotor control. These observations demonstrate that signals from the substantia nigra, superior colliculus and dentate nucleus can have a significant influence on the output of the FEF.

Animals↗
PubMed1994

[Intracranial cavernous angioma].

Clinical, radiological and histopathological features of eight cases of symptomatic cavernous angioma are presented. Five patients were being evaluated for seizure, two for mass lesions and one for intracranial hemorrhage. CT and/or MRI detected the lesion in all cases, but there is not a characteristic image for cavernous angioma. Good results were obtained by microsurgical approach to these malformations in seven patients with only one patient suffering a worsening of neurological status after surgery.

Adolescent↗
PubMed1994

Prediction of postoperative complications after elective aortic surgery using stepwise logistic regression analysis.

Perioperative risk factors that contribute to postoperative morbidity have been identified for various forms of vascular disease, but it is not clear to what degree each type of disease contributes to morbidity when these diseases are seen in combination. We used stepwise logistic regression analysis to determine the relative importance of 25 risk factors in predicting postoperative complications in 100 consecutive patients undergoing elective intra-abdominal aortic surgery (59% aneurysmal disease, 37% occlusive disease, 26% renal artery lesions). Thirty-one patients developed postoperative complications, including three deaths. The most common complication was deterioration in renal function (17 patients, 24% of those at risk) followed by the need for prolonged endotracheal intubation (> 48 hours, 8%). All other events occurred uncommonly (4% or less). Stepwise logistic regression demonstrated four criteria that were significantly associated with complications. In descending order of importance these were: renal artery occlusive disease, intraoperative blood replacement, the preoperative APACHE II score, and a history of heavy smoking. Since both physiologic status and comorbid conditions contribute to morbidity and costs of elective vascular surgery, outcome studies must be adjusted to account for these preoperative characteristics. Additionally, since two-thirds of patients who have renal artery occlusive disease develop complications that prolong hospitalization, our current methods of protecting the kidney during ischemia should be improved to potentially reduce this cause of morbidity.

Adult↗
PubMed1993

Unilateral pterional approach to bilateral cerebral aneurysms.

Between 1976 and 1991, we determined that 19 patients harboring bilateral supratentorial aneurysms should be approached in a single sitting through a unilateral pterional craniotomy. Using microsurgical techniques, the Sylvian cistern was opened widely to expose the aneurysms located ipsilateral to the craniotomy. These aneurysms were clipped in the usual fashion. Following clipping, a tunnel was developed over the contralateral anterior cerebral artery and over or under the contralateral optic nerve allowing access to the opposite carotid and middle cerebral arteries. The contralateral nonruptured aneurysms were clipped in a routine fashion. We were able to clip or wrap with muscle all bilateral aneurysms in 15 cases, and we have concluded that this approach can be safely employed in selected patients with bilateral supratentorial aneurysms, and thus a second craniotomy can be avoided.

Adult↗