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Biomedical subjects

X Navarro

Publications and source records attributed to X Navarro.

85 records · Page 5Linked to original sources
PubMed1988

Reinnervation of sweat glands in the mouse: axonal regeneration versus collateral sprouting.

The capacity of sudomotor axons to reinnervate sweat glands by regeneration after freezing was compared with their capacity to reinnervate by the mechanism of collateral sprouting. Two groups of mice were prepared in the same manner, with a single exception. All nerves to the hind paw were cut and tied to prevent regrowth. The exception, the lateral plantar nerve, was left intact in one group and frozen at the ankle in the other group. Reinnervation of sweat glands in the paw was charted frequently for 10 weeks using a silastic mold method. We found that sudomotor axons regenerating from the frozen nerve functionally reinnervated sweat glands of the paw sooner, beginning at 15 days postoperation, and at a higher rate than reinnervation from the collateral branching intact nerve, that began at about 25 days. Full recovery occurred by 41 days in most animals of both groups. We also found that stimulation of sweating by pilocarpine activated more sweat glands during the reinnervation period than stimulation by heating the mice, suggesting that the newly regenerating sudomotor axons have a high threshold.

Animals↗
PubMed1988

The effect of pancreas transplantation on diabetic polyneuropathy.

Neuromuscular function was evaluated in long-term type I diabetic patients who retained a functioning pancreas graft. A group of 34 patients was examined at 1 year and another group of 11 patients at 2 years after pancreas transplantation. In this report the clinical and electrophysiological course of motor features of polyneuropathy are described. Before pancreas transplantation, clinical evidence of polyneuropathy was present in all patients. The mean motor nerve conduction velocities (NCV) were below normal and the mean amplitude of the evoked muscle action potentials (MAP) were in the low normal range. The observed abnormalities of muscle strength and tendon reflexes had not progressed in these intervals. Motor NCV improved slightly and MAP amplitude was essentially unchanged. These preliminary results indicate that the progression of diabetic polyneuropathy may be halted by successful pancreas transplantation.

Adolescent↗
PubMed1988

Plasma lipids and their fatty acid composition in multiple sclerosis.

We report an extensive study of the plasma lipid profile and fatty acid composition in 61 multiple sclerosis (MS) patients compared with 61 normal subjects. The main abnormality in the MS was a reduction in the proportion of linoleic and arachidonic acids mostly evident in the HDL and in the cholesteryl esters fraction, with a compensatory increase in saturated acids. The fatty acid abnormalities correlated with the duration of the disease and the degree of disability. Thus, in the MS patients studied there was a deficiency in essential fatty acids, although this metabolic abnormality does not seem specific to MS.

Adult↗
PubMed1988

Long-term follow-up of polyneuropathy in diabetic kidney transplant recipients.

Nerve conduction and electromyography (EMG) of insulin-dependent (type 1) diabetic patients with end-stage nephropathy was studied before and up to 10 yr after kidney transplantation (KTx). A series of nondiabetic KTx patients served as a comparison group. Motor nerve conduction velocity (NCV) was measured in the ulnar, median, peroneal, and tibial nerves; sensory NCV was measured in the median nerve. EMG was performed in the first dorsal interosseus, flexor carpi radialis, anterior tibialis, and gastrocnemius muscles. In 68 pre-KTx diabetic patients, the mean NCV was below normal in all nerves, and the mean amplitudes of the evoked muscle action potential (MAP) were low normal in the upper extremity and below normal in the lower extremity. The values of the comparison group were within the normal range. At 1 (n = 57), 5 (n = 23), and 10 (n = 10) yr after KTx, the mean NCV of the diabetic patients remained essentially unchanged, but MAP amplitudes of all muscles had declined. EMG revealed progression of the denervation process, especially in muscles of the lower extremities. We conclude that diabetic neuropathy continues to progress by a progressive axonal loss after correction of uremia by KTx.

Action Potentials↗
PubMed1988

Pancreas transplantation in nonuremic, type I diabetic recipients.

Between July 1978 and January 1988, 111 of 210 pancreas transplants were in nonuremic, nonkidney (NUNK) recipients in whom complications of diabetes were judged more serious than the potential side effects of antirejection therapy. In all NUNK cases, the 1-year patient survival rate (PSR) and graft survival rate (GSR) were 90% and 39%. Since November 1984, 1-year PSR and GSR for 62 NUNK recipients of pancreas transplants alone (PTA) were 93% and 48%, compared to 89% and 37% for 28 pancreas transplants after (PAK) and 89% and 73% for 20 simultaneous (SPK) with a kidney transplant. The 1-year GSR for 1984-88 technically successful (TS) PTA cases (n = 47) was 63%, versus 75% for PAK (n = 13) and 86% for SPK (n = 17) cases. The 1-year GSRs, by technique and source for 1984-88 PTA cases, were 58% for bladder-drained cadaver (n = 30), 51% for enteric-drained related (n = 32), and 29% for enteric-drained cadaver (n = 17) donor transplants, and 75% (n = 24), 77% (n = 16), and 38% (n = 13) for the corresponding TS cases. Of NUNK recipients, 35 have had grafts function for more than 1 year and all but 3 were treated with cyclosporine (CsA). In the CsA-treated recipients, serum creatinine increased and creatinine clearances decreased by a magnitude of 40% during the first 6 months but thereafter remained stable in all but 2 patients. In the patients with functioning grafts studied at 1 year, retinopathy remained stable in 59% and progressed in 41% of the eyes (n = 39). Motor nerve conduction velocities were significantly increased and muscle action potentials remained stable in 24 patients with functioning grafts studied at 1 year, while in 14 patients in whom transplants failed there was a significant decrease in evoked muscle action potentials. A sustained euglycemic, insulin-independent state can be established in nonuremic, nonkidney diabetic recipients of pancreas transplants alone, with a beneficial effect on neuropathy, lack of an immediate benefit on advanced retinopathy, and an effect on nephropathy compounded by the influence of CsA on renal function.

Cyclosporins↗
PubMed1988

Fatty acids of plasma and red blood cell lipids in a normal population.

A detailed study of the fatty acid composition of each of the lipids present in plasma and red blood cells of 62 healthy subjects of our area (Barcelona and surrounding counties), by coupling thin-layer and gas chromatography techniques has been made. The results are presented as normative data for comparison with those found in pathological situations. No significant sex differences were found. With increasing age, there was a tendency for the proportion of linoleic acid to decrease. Correlation analyses between the fatty acid composition of different lipids suggested that the interchange of fatty acids between plasma and cells mainly affects the phosphatidylcholine of the latter.

Adolescent↗
PubMed1987

Geographical distribution of multiple sclerosis mortality in Spain.

Mortality from multiple sclerosis in Spain has been analyzed for the period 1969-1979. In this period 1841 deaths from MS as primary cause were registered. The death rate decreased markedly during the first years, but was steady between 1975 and 1979 with 0.35 deaths per 100,000 population. This value places Spain within the low-medium risk zone of MS. The geographical distribution by provinces shows a slight northern predominance, with the highest rates in the northwestern area.

Epidemiologic Methods↗
PubMedDate not supplied

Functional changes of the peripheral nervous system with aging in the mouse.

The influence of aging on peripheral nerve and target organ function was investigated in six groups of mice aged 2, 6, 9, 12, 18, and 24 months. Sudomotor, motor, and sensory functions mediated by the sciatic nerve were evaluated by silicone imprints, electrophysiological recordings and pinprick test from the distal hindpaw. Nerve conduction was also studied in the caudal nerves. The results showed that the number of sweat glands reactive to pilocarpine does not change significantly with aging, but the size of the sweat droplets is smaller in aged mice than in young mice. The amplitude of muscle and nerve action potentials evoked by stimulation of sciatic and caudal nerves decreased progressively from 2 to 24 months, while the latencies decreased from 2 to 6 months, remained unchanged until 12 months and increased thereafter. All the animals of the six groups studied showed positive, indistinguishable responses to pinprick. These results indicate that neurophysiological responses mediated by large diameter nerve fibers deteriorated with age, while those dependent of small fibers were preserved.

Aging↗
PubMedDate not supplied

[Physiology of the autonomic nervous system].

INTRODUCTION: The autonomic nervous system (ANS) is made up of a complex set of neurons and pathways that control the functioning of the different body systems within the organism. Its overall function is that of maintaining a state of homeostasis in the organism and of performing the adaptation responses when faced with changes in the external and internal environment. METHODS: The ANS is composed of visceral afferent pathways, integration centres at the brain stem, hypothalamus and cerebral cortex levels, as well as sympathetic and parasympathetic efferent pathways. The efferent pathways innerve the cardiac muscle, the smooth muscle and the exocrine and endocrine glands, while the afferent pathways are arranged in two patterns: oligosynaptic circuits, which mediate reflex adaptation responses of the visceral systems, and complex circuits, with projections to nuclei in the brain stem and the brain, where the information is collected and responses are produced that affect numerous systems. The afferent signals activate or inhibit the efferent components of the ANS by means of reflex pathways, independently of the will. These reflex circuits are also modulated by means of signals from central structures, and constitute a central autonomic neuronal network that integrates somatic, autonomic and affective responses. CONCLUSION: Dysfunctions of the ANS are possibly due to increases or decreases in autonomic control activity, which can appear because of lesions to the brain, spinal cord or peripheral nerves.

Autonomic Denervation↗
PubMedDate not supplied

[Autonomic neuropathy in diabetes mellitus].

AIMS: We analyse the different studies conducted on the prevalence, aetiopathology, clinical symptoms and treatment of diabetic autonomic neuropathy (AN), together with its involvement in the mortality of patients. DEVELOPMENT: AN can affect any part of the nervous system to varying degrees and at different moments in time, and its prevalence is significant in any of the stages of diabetes. The aetiopathogenesis of AN results from a multifactorial process involving metabolic disorders triggered by the activation of the polyolic pathway, microangiopathy and alterations affecting the synthesis of essential fatty acids due to hyperglycemia, which is made worse by a deficient regeneration of nerve tissue. Any of the systems innervated by the autonomous nervous system can be affected; the initial symptoms are insidious and of little cause for concern until the more advanced stages of the disease. The chief dysfunctions affect the cardiovascular, digestive, genitourinary and thermoregulatory systems. How AN courses in time varies from patient to patient and depends on the glycemic control that is carried out. Its presence is a factor that increases the mortality rate in diabetic patients. CONCLUSIONS: The prevalence of AN is notable, and the symptoms of autonomic dysfunction are usually under-diagnosed owing to its variability, lack of specificity and the wide range of symptoms. It is important to recognise this entity because of its effects on increasing morbidity and mortality, although they can be reduced by means of a strict glycemic control and specific treatment.

Autonomic Nervous System↗
PubMedDate not supplied

[Methodological considerations concerning peripheral nerve morphometry].

Morphometric studies of the peripheral nerve often present widely varying results which, in part at least, may be attributed to the different methodologies used. Two questions may be of importance with regard to the reliability of such results: the preselection of fibres according to their morphology and the method used in quantifying observations. In this work a morphological study was carried out on the myelinated fibres of the sciatic nerve of a rat in order to evaluate fibre selection criteria. A morphometric analysis was also performed using manual measurements, image digitalisation and surveying, and automatic image analysis. It was shown that morphological variability of transverse section fibres is considerable and that, really, the proportion of circular fibres with homogeneous compact myelin is only 50 to 70%, from which we can conclude that the selection of fibres carried out in some studies wishing to eliminate abnormal fibres is somewhat exaggerated. By analysing the fibres using various methods significant differences appear, some due to the fact that distinct methods may be used to calculate the same parameters in a different way. The most reliable parameters would appear to be those which do not depend on the shape of the fibres and those which automatic or semiautomatic methods can calculate directly such as areas and perimeters. In any case quantifying methods seem hardly discriminatory and the differences between methods disappear if analyses are carried out using random samples. Preselection of fibres appears unnecessary in this context as in no case are the results altered. Finally we suggest finishing quantitative analyses with qualitative studies which would permit getting more information especially useful in cases of ageing, regeneration or pathological studies.

Aging↗
PubMedDate not supplied

[Degeneration and regeneration of the peripheral nervous system with aging].

Clinical and experimental studies have shown that with aging there appear neurological changes which affect both the Central Nervous System (CNS) as well as the Peripheral Nervous System (PNS), bringing about a series of cognitive, sensory and physical disabilities in older people. Nerve lesions also cause disability. The basic mechanisms which begin with lesioned neurons have proved an interesting field of study for many neuroscientists since as far back as the mid-nineteenth century. However the influence of age on these postlesion neuronal processes has not aroused the same level of interest even though many authors have, out of curiosity, published reports of changes which take place in regenerative neurons as a result of age. The progressive increase in the aged population in industrialised nations warrants a detailed study into the influence of age on such neuronal processes. The PNS, due to its accessibility and greater regenerative potential vis-à-vis the CNS, may be a good model for this purpose. From results obtained by both other authors and ourselves it is clear that aging causes a decline in the regenerative abilities of peripheral nerve fibres. Functional recovery is not only slowed down but also decreases with age. The number of regenerative axons and their capacity for end sprouting, together with the biosynthesis and transport of new materials in the regenerative neurons, as well as the proliferation and synthesis of trophic factors by Schwann cells also decay. All of this leads to the fact that the regenerative capacity of nerve fibres is lesser with age, and that functional disabilities after a lesion are greater in older than in younger people.

Aging↗