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Biomedical subjects

N Martin

Publications and source records attributed to N Martin.

At least 181 records · Page 10Linked to original sources
PubMed1993

A combined intradural presigmoid-transtransversarium-transcondylar approach to the whole clivus and anterior craniospinal region: anatomic study.

Surgical exposure of the clivus is difficult because of its proximity to vital neurovascular structures. The anatomic bases of a new surgical approach to this area are discussed. A supra-auricular skin incision is extended toward the posterior border of the sternocleidomastoid muscle. The vertebral artery is exposed from C2 to the occiput unroofing the foramen transversarium of C1. The bone removal consists of a posterior temporal craniotomy, a suboccipital craniectomy, including mastoidectomy with sigmoid sinus unroofing, removal of the lateral margin of the foramen magnum, of the medial third of the occipital condyle, and retrolabyrinthine petrous drilling. Posterior retraction of the vertebral artery facilitates occipital condyle drilling. Intradural exposure of the petroclival region is achieved by L-shaped cutting of the dura with the long branch placed infratentorially anterior to the sigmoid sinus. Intradural exposure of the craniospinal/upper cervical areas is achieved by cutting of the dura medial to the distal sigmoid sinus and by longitudinal cutting of the dura anterior to the vertebral artery. This approach allows multiple ports of entry to the clivus with full control of the vertebrobasilar system, and of the dural sinuses, and is anatomically suited for controlled removal of tumors located in these areas. This approach, or segments of it, has been used successfully in the treatment of large neoplasms of the craniovertebral junction.

Journal Article↗
PubMed1993

Monitoring carotid test occlusions with continuous EEG and clinical examination.

We routinely monitor invasive neuroradiologic carotid balloon test occlusions with continuous polygraph and quantitative EEG along with repeated detailed clinical examinations. Four of 17 consecutive cases showed changes during carotid occlusion. In one instance, an immediate delta increase was accompanied by slurred speech and aphasia. Another showed alpha attenuation without clinical change. A third patient had significant clinical change without EEG change. Nine of the 17 cases underwent permanent therapeutic carotid occlusion as treatment of an intracerebral vascular abnormality. Seven of these nine had no EEG or clinical changes during monitoring and have had no functional abnormalities on follow-up. The patient with focal alpha attenuation had an accidental balloon detachment but has had no functional or structural neurologic abnormalities. The patient with minor regional increased delta received a permanent carotid occlusion and went on to develop clinical signs 24 h later. We believe that continuous EEG monitoring and repeated clinical examinations provide useful ways of evaluating cerebral circulation during carotid test occlusions.

Adult↗
PubMed1993

Therapeutic alternatives for vein of Galen vascular malformations.

From September, 1986, to March, 1990, the authors treated 28 children harboring a vein of Galen vascular malformation. Eleven (39.3%) of the patients were neonates, 13 (46.4%) were 1 to 2 years old, and four (14.3%) were more than 2 years old. Fifteen patients (53.6%) presented with severe congestive heart failure, six (21.4%) had seizures, four (14.3%) had hydrocephalus, and three (10.7%) presented with intraventricular hemorrhage. Based on the Yaşargil classification of malformations, 10 lesions (35.7%) were Type I, seven (25%) were Type II, eight (28.6%) were Type III, and three (10.7%) were Type IV. In 11 patients (39.3%), a combined transfemoral, transarterial, and transvenous embolization of the vein of Galen malformation was performed. A pure transtorcular approach was utilized in eight patients (28.6%), and postembolization surgical clipping of arterial feeders was performed in two cases with intractable congestive heart failure. Complete anatomical occlusion of the galenic malformation was achieved in 13 patients (46.4%). An immediate postembolization improvement in the patient's clinical status was obtained in 23 (82.1%) of 28 patients and a good long-term clinical outcome was seen in 17 patients (60.7%). Five deaths (17.9%) occurred in this series of 28 patients; three (10.7%) were related to a transtorcular embolization and two (7.1%) to the unchanged natural history of the disease.

Cerebral Veins↗
PubMed1993

Comparison of inversion restraint provided by ankle prophylactic devices before and after exercise.

The prudence of prophylactic ankle taping continues to be questioned as recent studies have identified other forms of ankle stabilization as more effective means of injury prevention. The purpose of our study was to compare the effectiveness of three ankle prophylaxes (adhesive taping, lace-up brace, and semirigid orthosis) with a control condition (no support) in limiting inversion under dynamic loads imposed by repetitive walking (4 mph) and running (9 mph) on an 8.5 degrees laterally tilted treadmill. Ten subjects participated in four separate testing sessions in which they were videotaped while walking and running on a tilted treadmill before and after 20 minutes of vigorous exercise. Average maximum inversion angle was determined through biomechanical analysis of rearfoot motion for each experimental condition and analyzed with repeated measures ANOVA and Scheffé post hoc tests. There were significant differences in the average maximum inversion angle between the ankle devices at 4 and 9 mph, and between pre-exercise and postexercise measurements at 4 mph, between the semirigid orthosis and the control condition at 4 and 9 mph, and between the lace-up brace and the control condition at 4 mph. Overall, the semirigid orthosis provided the most inversion restraint during dynamic loading, followed by the lace-up brace, tape, and control condition. We concluded that the lace-up brace and semirigid orthosis evaluated were very similar in restricting inversion, and that both devices limited postexercise inversion significantly more than ankle taping.

Journal Article↗
PubMed1993

[Results of systematic programmed ventricular stimulation after myocardial infarction. Which protocol should be recommended?].

The authors report the prognostic value of ventricular arrhythmias induced by routine programmed ventricular stimulation after the acute phase of myocardial infarction. The protocol consisted of two extrastimuli in the first 185 patients and 3 extrastimuli in 308 patients. The use of 3 extrastimuli increased the incidence of inducible sustained monomorphic ventricular tachycardia (VT) < 270/mn, from 17 to 22% and, more importantly, that of ventricular fibrillation from 4 to 17%. Induction of ventricular flutter (monomorphic VT > 270/mn) was not increased. A long follow-up period (average 4 +/- 2 years) showed that the risk of VT was increased during the first months after infarction (n = 14), and that, 4 years later, other patients develop VT (n = 6). The risk of serious arrhythmias (VT and sudden death) was significantly higher in patients with inducible VT < 270/mn (20%) than in patients without inducible VT, but it was also higher in patients with inducible ventricular flutter (12.5%). The use of a third extrastimulus has a low positive predictive value for arrhythmic events (10%). This study confirms that the induction of sustained monomorphic VT after myocardial infarction is associated with an increased risk of arrhythmic events but the positive predictive value is relatively low (17%). In view of the risk of inducing non-specific ventricular fibrillation, the authors recommended using a stimulation protocol with only 2 ventricular extrastimuli.

Arrhythmias, Cardiac↗
PubMed1993

Immunologic changes occurring at kindergarten entry predict respiratory illnesses after the Loma Prieta earthquake.

Previous studies in adult populations have demonstrated alterations in immune function after psychologically stressful events, and pediatric research has shown significant associations between stress and various childhood morbidities. However, no previous work has examined stress-related immune changes in children and subsequent illness experience. Twenty children were enrolled in a study on immunologic changes after kindergarten entry and their prospective relationship to respiratory illness (RI) experience. Midway through a 12-week RI data collection period, the October 17, 1989 Loma Prieta earthquake occurred. The timing of this event created a natural experiment enabling us to study possible associations between immunologic changes at kindergarten entry, the intensity of earthquake-related stress for children and parents, and changes in RI incidence over the 6 weeks after the earthquake. Immunologic changes were measured using helper (CD4+)-suppressor (CD8+) cell ratios, lymphocyte responses to pokeweed mitogen, and type-specific antibody responses to Pneumovax, in blood sampled 1 week before and 1 week after school entry. RI incidence was assessed using home health diaries and telephone interviews completed every 2 weeks. RIs per child varied from none to six. Six children showed an increase in RI incidence after the earthquake; five experienced a decline. Changes in helper-suppressor cell ratios and pokeweed mitogen response predicted changes in RI incidence in the postearthquake period (r = .43, .46; p < .05). Children showing upregulation of immune parameters at school entry sustained a significant increase in RI incidence after the earthquake.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody Formation↗
PubMed1993

[Sturge-Weber-Krabbe syndrome. A severe form in a monozygote female twin].

We report a severe case of Sturge-Weber syndrome in one of two monozygotic twins. This syndrome included a facial portwine stain over the trigeminal ophthalmic V1 area, and ipsilateral vascular anomalies of the eye and of the pia mater. CT scans and MRI were very informative. The cerebral regional blood flow, studied with SPECT, showed a paradoxically high rate.

Brain↗
PubMed1993

Mitogenic effect of transforming growth factor-beta 1 on human Ito cells in culture: evidence for mediation by endogenous platelet-derived growth factor.

We assessed the effect of transforming growth factor-beta 1 on the proliferation of human Ito cells. Ito cells in their myofibroblastlike phenotype were grown from explants of human liver and were characterized with electron microscopy and positive immunostaining for desmin and smooth muscle alpha-actin. Transforming growth factor-beta 1 was mitogenic for human Ito cells whatever the culture conditions, although it was, as previously described, inhibitory of growth for rat Ito cells. The mitogenic effect of transforming growth factor-beta 1 was likely due to induction of autocrine platelet-derived growth factor chain secretion by Ito cells themselves because (a) the mitogenic effect of transforming growth factor-beta 1 was blocked by specific platelet-derived growth factor antibodies, (b) transforming growth factor-beta 1 increased platelet-derived growth factor-A chain messenger RNA expression and platelet-derived growth factor-AA secretion by human Ito cells and (c) human Ito cells expressed the alpha-type platelet-derived growth factor-A receptor messenger RNA. Exogenous platelet-derived growth factor-AA was also mitogenic for human Ito cells, mimicking the effect of transforming growth factor-beta 1. Our data suggest that results obtained with rat Ito cells must be extrapolated with caution to human ones. The mitogenic effect of transforming growth factor-beta 1 on human Ito cells probably has pathophysiological relevance because transforming growth factor-beta 1 has been demonstrated in vivo at sites of active liver fibrogenesis.

Actins↗
PubMed1993

Cardiac conduction abnormalities during carbamazepine therapy for neuralgia following Guillain-Barré syndrome.

A 61-year-old man without previous medical history was admitted for Guillain-Barré syndrome (GBS). Carbamazepine was prescribed on day 72 for dysesthesia occurring at the time of recovery. Subsequently, severe cardiac conduction disturbances (asystole, atrioventricular block) were observed and a permanent pacemaker had to be inserted. The possible relationship between carbamazepine therapy and cardiac side effects is discussed in this condition, as GBS itself is often complicated by cardiac arrhythmias.

Carbamazepine↗
PubMed1993

Intracranial dural arteriovenous fistulas and sinus thrombosis. Report of five cases.

Dural arteriovenous fistula and sinus thrombosis are sometimes associated. The relationship between these two conditions remains unclear. Thrombophlebitis of the dural sinus may induce a dural fistula. Conversely, thrombophlebitis is sometimes observed in the course of dural fistulas. We report five cases of dural arteriovenous fistulas associated with sinus thrombosis. In three cases, the angiographic and pathological data indicated the responsibility of thrombosis in the occurrence of the fistula. In the others two cases, thrombophlebitis and fistula were simultaneously diagnosed by angiography. However, in one of these cases, the clinical data showed that the fistula probably was a causative factor in the occurrence of thrombophlebitis.

Adult↗
PubMed1992

cDNA cloning and sequencing of rat alpha 1-macroglobulin.

cDNA clones coding for the plasma protease inhibitor alpha 1-macroglobulin were isolated from a rat liver library. The obtained cDNA sequence contained 4701 nucleotides and had an open reading frame coding for a 1,500 amino acid long protein, including a 24 amino acid signal peptide. The identity of the deduced protein sequence as alpha 1-macroglobulin was established by comparison with published peptide sequences of the protein. The mature protein shares 53% and 57% overall amino acid identity with the two other identified members of the rat alpha-macroglobulin family, alpha 1-inhibitor 3 and alpha 2-macroglobulin. A sequence typical for an internal thiol ester was identified. Of the 24 cysteines, 23 are conserved with alpha 2-macroglobulin. However, instead of the two most C-terminal cysteines in alpha 2-macroglobulin, which forms a disulfide bridge in the receptor binding domain, alpha 1-macroglobulin contains phenylalanine. One mRNA species hybridizing with the alpha 1-macroglobulin probe was observed in rat and mouse liver RNA (approximately 6.2 kb), whereas no corresponding transcript was detected in RNA from human liver.

Amino Acid Sequence↗
PubMed1992

First-derivative spectroscopic determination of binding characteristics of rifampicin to human albumin and serum.

A first-derivative spectroscopic method for the simultaneous determination of bound and unbound drug in human serum and serum albumin solution was developed. As an example, the binding characteristics of rifampicin were studied. In serum albumin solution, the rifampicin bound and unbound fractions were determined at 473.5 and 475.8 nm, respectively. For human serum, the unbound fraction was determined at 479.4 nm. The results obtained by the first-derivative spectroscopic method were in agreement with those obtained by equilibrium dialysis. The proposed method is very simple and accurate when applied to measurements of drug:protein binding. Moreover, it allows a direct measurement of the bound and unbound forms without any physical separation.

Humans↗
PubMed1992

Facial nerve neuromas: MR imaging. Report of four cases.

Four cases of facial nerve neuroma were evaluated by computed tomographic (CT) scan and magnetic resonance imaging (MRI). The extension of the tumor in the petrous bone or the parotid gland was well defined by MRI in all cases. CT scan was useful to demonstrate bone erosions and the relation of the tumor to inner ear structures. In cases of progressive facial palsy, CT and MRI should be combined to detect a facial neuroma and to plan the surgical approach for tumor removal and nerve grafting.

Adult↗