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Biomedical subjects

J B Martin

Publications and source records attributed to J B Martin.

At least 37 records · Page 2Linked to original sources
PubMed2000

neo-inositol polyphosphates in the amoeba Entamoeba histolytica.

We have reexamined the structure of inositol phosphates present in trophozoites of the parasitic amoeba Entamoeba histolytica and show here that, rather than being myo-inositol derivatives (Martin, J.-B., Bakker-Grunwald, T., and Klein, G. (1993) Eur. J. Biochem. 214, 711-718), these compounds belong to a new class of inositol phosphates in which the cyclitol isomer is neo-inositol. The structures of neo-inositol hexakisphosphate, 2-diphospho-neo-inositol pentakisphosphate, and 2, 5-bisdiphospho-neo-inositol tetrakisphosphate, which are present in E. histolytica at concentrations of 0.08-0.36 mM, were solved by two-dimensional (31)P-(1)H NMR spectroscopy. No evidence for the co-existence of their myo-inositol counterparts has been found. These neo-inositol compounds were not substrates of 6-diphospho-inositol pentakisphosphate 5-kinase, an enzyme purified from Dictyostelium discoideum that phosphorylates 6-diphospho-myo-inositol pentakisphosphate and more slowly also myo-inositol hexakisphosphate, specifically on position 5. Because preliminary data indicate that large amounts of the same neo-inositol phosphate and diphosphate esters are also present in another primitive amoeba, Phreatamoeba balamuthi, the occurrence of high concentrations of neo-inositol polyphosphates may be much more general than previously thought.

Animals↗
PubMed2000

Effect of DHA supplementation on DHA status and sperm motility in asthenozoospermic males.

The effects of supplementation with docosahexaenoic acid (DHA) on DHA levels in serum, seminal plasma, and sperm of asthenozoospermic men as well as on sperm motility were examined in a randomized, double-blind, placebo-controlled manner. Asthenozoospermic men (n = 28; < or =50% motility) were supplemented with 0, 400, or 800 mg DHA/d for 3 mon. Sperm motility and the fatty acid composition of serum, seminal plasma, and sperm phospholipid were determined before and after supplementation. In serum, DHA supplementation resulted in decreases in 22:4n-6 (-30% in the 800-mg DHA group only) and total n-6 (-6 and -12% in the 400- and 800-mg DHA groups, respectively) fatty acids. Increases were noted in DHA (71 and 131% in the 400- and 800-mg DHA groups, respectively), total n-3 fatty acids (42 and 67% in the 400- and 800-mg DHA groups, respectively), and the n-3/n-6 ratio (50 and 93% in the 400- and 800-mg DHA groups, respectively). In seminal plasma, DHA supplementation resulted in a decrease in 22:4n-6 (-31% in the 800-mg DHA group only) and an increase in the ratio of n-3 to n-6 (35 and 33% in the 400- and 800-mg DHA groups, respectively). There were insignificant increases in DHA and total n-3 fatty acids. In sperm, decreases were noted in 22:4n-6 (-37 and -31% in the 400- and 800-mg DHA groups, respectively). There were no other changes. There was no effect of DHA supplementation on sperm motility. The results show that dietary DHA supplementation results in increased serum--and possibly seminal plasma--phospholipid DHA levels, without affecting the incorporation of DHA into the spermatozoa phospholipid in asthenozoospermic men. This inability of DHA to be incorporated into sperm phospholipid is most likely responsible for the observed lack of effect of DHA supplementation on sperm motility.

Adult↗
PubMed2000

Endovascular repair using vein-covered stents in the carotid artery bifurcation.

The treatment of a bleeding carotid artery pseudoaneurysm in a patient using endovascular repair is described. Vein-covered stents were successfully employed. There were no neurological complications and no recurrent bleeding during 8 months follow up and carotid artery continuity was achieved. Stents covered with saphenous vein may be considered a treatment option for endovascular repair of pseudoaneurysm of the carotid artery.

Aneurysm, False↗
PubMed2000

Breaking down the walls: thoughts on the scholarship of integration.

The scholarship of integration is concerned with making connections across scientific disciplines, placing the work of individual investigators and their specialty fields into a larger context, and educating nonspecialists. The authors focus their comments on the biomedical sciences, but observe that closer integration of the biomedical and behavioral sciences will be particularly crucial to advance understanding of the human brain. They observe that as biomedical sciences become more technologically sophisticated, progress is increasingly dependent on sciences such as physics, chemistry, engineering, and related fields. However, the scholarship of integration has been slower than other forms of scholarship to gain acceptance as an integral activity of the professoriate. The isolation of disciplines from one another, particularly at large universities, and the perception of interdisciplinary work as risky and professionally unrewarding are among the forces that may discourage integrative scholarship. In addition, a troubling disconnect exists between the scientific community and the larger public in the understanding of science. Leaders in academic medicine and science must develop strategies to move interdisciplinary work from the margins into the mainstream of academia. Solutions that have been proposed include creating new research entities and funding mechanisms dedicated to interdisciplinary work; reinvigorating the integrative role of the physician-scientist; and training specialists in translational research. The scientific community must also work to develop more effective means of communicating the importance of its work to the public.

Academic Medical Centers↗
PubMed2000

Neurovascular embolization: in vitro evaluation of a mechanical detachable platinum coil system.

The authors evaluated a mechanically detachable platinum coil system intended for neurovascular use. The introduction characteristics, ease of delivery, ease of retrieval, and detachability were studied with fluoroscopic guidance with in vitro silicone models. All the coils passed easily through the microcatheter. The detachment maneuver occurred within 20 seconds with 20 or fewer rotations of the pusher wire. One of 229 coils detached prematurely but only after deliberate and extreme manipulation. The detachment system is safe, reliable, and consistent and will be useful for interventional neuroradiologists.

Cerebrovascular Disorders↗
PubMed2000

The effect of contrast material on transcranial Doppler evaluation of normal middle cerebral artery peak systolic velocity.

BACKGROUND AND PURPOSE: Several recent studies have shown that sonographic contrast agents may affect transcranial Doppler evaluation of the arterial peak systolic velocity (PSV). Some investigators reported an increase in PSV, and others reported no change in PSV compared with baseline values. This study was conducted to determine the effect of sonographic contrast agent on PSV measured in normal middle cerebral arteries. METHODS: Continuous spectral Doppler sonography was performed on the right middle cerebral artery of 20 participants with angiographically proven normal intracranial vasculature. Videotaping was performed in each case from the initiation of the administration of contrast medium until the effect of the contrast agent on the PSV subsided. The PSV values were normalized for each participant, were pooled, and were plotted as a function of time. RESULTS: PSV increased in all participants after the administration of contrast material; the mean maximum increase was 24+/-7.4% (mean +/- standard deviation) (range, 15-36%). The mean duration of PSV increase was 320+/-97 s (range, 165-465 s). CONCLUSION: The middle cerebral artery PSV increased substantially after the administration of contrast material. This effect needs to be considered if velocity thresholds developed for disease detection without the use of contrast materials are used when contrast agents are administered.

Adolescent↗
PubMed2000

Percutaneous transluminal angioplasty and stenting of the proximal vertebral artery for symptomatic stenosis.

BACKGROUND AND PURPOSE: Percutaneous transluminal angioplasty (PTA) for significant stenosis involving the origin of the vertebral artery is now a well established treatment for selected patients when posterior cerebral arterial circulation is compromised. Arterial spasm, dissection, and restenosis may occur in some instances, with subsequent hemodynamic compromise. To prevent these potential complications, we combined PTA of the vertebral artery with primary stenting, using coronary stents, in seven patients. We herein present our short- and intermediate-term results. METHODS: A total of seven lesions affecting the origin of the vertebral artery were treated by primary trans-stenotic coronary stent placement. All patients were symptomatic, fulfilling the general criteria for vertebral artery angioplasty. Patients were followed for up to 36 months after treatment. RESULTS: All seven lesions were successfully dilated. Residual stenosis was never greater than 20% in diameter. No perioperative complications occurred. Clinical follow-up showed immediate resolution or improvement of symptoms in all patients. One patient's condition deteriorated 15 months after stent placement because of atheromatous stenosis of the prevertebral segment in the ipsilateral subclavian artery. CONCLUSION: Stent placement to treat significant stenosis involving the origin of the vertebral artery is safe and effective for alleviating symptoms and improving blood flow to the posterior cerebral circulation. Coronary stent design seems to be particularly well suited to cover atherosclerotic lesions of the origin of the vertebral artery. The stent mesh probably prevents elastic recoil and early restenosis after PTA, as it does in coronary arteries.

Aged↗
PubMed2000

Dense packing of cerebral aneurysms: an in vitro study with detachable platinum coils.

Aneurysm models were used to study the density of packing after coil embolization. Platinum coils were introduced until the point of minimally dense packing, indicated by aneurysmal circulatory exclusion. Packing was continued up to the point of maximal density, indicated by protrusion into the parent artery. Volumetric ratios (coil volume/aneurysmal volume) were calculated for minimally and maximally dense packing. Maximally dense packing ratios were a little higher than the minimally dense ratios, but less than 37%.

Implants, Experimental↗
PubMed1999

Fatty acid analysis of blood serum, seminal plasma, and spermatozoa of normozoospermic vs. asthenozoospermic males.

Docosahexaenoic acid (DHA; 22:6n-3) is found in extremely high levels in human ejaculate with the majority occurring in the spermatozoa. However, the relative concentration of DHA and other fatty acids, in blood serum, seminal plasma, and spermatozoa of asthenozoospermic vs. normozoospermic individuals is not known. We analyzed the phospholipid fatty acid composition of blood serum, seminal plasma, and spermatozoa of normozoospermic men and asthenozoospermic men in order to determine if DHA levels, as well as the levels of other fatty acids, differed. The serum phospholipid DHA levels were similar in the two groups, suggesting similar intakes of dietary DHA. On the other hand, seminal plasma levels of DHA (3.0 vs. 3.7%) and total polyunsaturated fatty acids (PUFA) (11.8 vs. 13.5%) were significantly lower in asthenozoospermic vs. normozoospermic men, respectively, while 18:1 (19.0 vs. 16.8%) and monounsaturated fatty acids (MUFA) (24.2 vs. 21.7%) were significantly higher in the asthenozoospermic vs. the normozoospermic men. Spermatozoa from asthenozoospermic men had higher levels of 18:1, 20:0, 22:0, 22:1, and 24:0 than sperm from normozoospermic men, and lower levels of 18:0 and DHA (8.2 vs. 13.8%). Furthermore, total MUFA (19.3 vs. 16.5%) was higher and total PUFA (19.0 vs. 24.0%), n-3 fatty acids (9.3 vs. 14.6%), and the ratio of n-3 to n-6 fatty acids (1.0 vs. 1.6) were lower in the asthenozoospermic men. Therefore, in asthenozoospermic individuals, lower levels of DHA in the seminal plasma, but not in the blood serum, mimic the decreased concentrations of DHA in the spermatozoa. This suggests that the lower concentrations of spermatozoon DHA in these individuals are due not to dietary differences but to some type of metabolic difference in the asthenozoospermic men.

Docosahexaenoic Acids↗
PubMed1999

Vertebroplasty: clinical experience and follow-up results.

This study was undertaken to report the clinical experience with percutaneous minimal invasive vertebroplasty using polymethyl-methacrylcate (PMMA) for a consecutive group of patients. Over the period of the last 4 years, 40 patients were treated at 68 vertebral segment levels with the intention to relieve pain related to vertebral body lesions. Reduced vertebral body height and destruction of the posterior vertebral wall were not considered to be exclusion criterias. The vertebroplasty procedure was performed under general anesthesia and in prone position with imaging control using mostly biplane DSA fluoroscopic guidance, and rarely with single-plane mobile DSA combined with computed tomographic guidance. Unilateral, but more frequently bilateral, transpedicular introduction of a 2-3-mm OD needle was followed by an injection of polymethyl-methacrylcate (PMMA). PMMA preparation involved a diluted mixture (20 mL powder for 5 mL liquid) allowing for an extended polymerization time of up to 8 min. The PMMA was mixed with metallic powder to enhance its radio-opacity. Before PMMA injection, a vertebral phlebography was obtained to evaluate the filling pattern and identify sites of potential PMMA leakage. Injection of opacified PMMA was performed under continuous visual control with fluoroscopy to obtain adequate filling and to avoid important PMMA leakage. Clinical follow-up involved an evaluation using a questionnaire for assessment of pain, pain medication, and mobility. One to six levels were treated in one to three treatment sessions for patients with metastatic, osteoporotic, and hemangiomatous lesions of the vertebral bodies who presented with pain. The results observed matched those reported previously with a success rate of approximately 80% and a complication rate below 6% per treated level. Treatment failure and complications observed were related to leakage, insufficient pretreatment evaluation, anesthesia, or patient position during treatment. Image guidance with fluoroscopy was efficient both for precise transpedicular approach and PMMA implantation control. Vertebroplasty is very efficient for treatment of pain. Treatment failure was mostly related to insufficient pretreatment clinical evaluation, and complication due to excessive PMMA volume injection. Control of PMMA volume seems to be the most critical point for avoiding complications. A good fluoroscopy control is therefore mandatory.

Adult↗
PubMed1999

Pathology findings with acrylic implants.

We report the pathological findings in cases of acrylic implants obtained by direct intratumoral injection of polymethyl-methacrylate (PMMA) and N-butyl-cyano-acrylate (NBCA). Direct intratumoral injection of acrylic implants was performed for a variety of primary and secondary bone lesions. These types of treatments have been used at our institution in the last 4 years for 40 vertebroplasty (PMMA) procedures and for nine bone lesions of other locations (PMMA, NBCA). Postmortem histology became available for 1 case of PMMA and for 5 cases with NBCA intratumoral acrylic implants. The pathological findings associated with PMMA and NBCA were evaluated and compared. PMMA exhibited a macroscopic and microscopic rim of tumor necrosis, 6 months after implantation. NBCA exhibited compressive effects on the nearby tumor tissue, however, without signs of significant necrosis outside the acrylic tumor cast. Tumor captured inside the acrylic cast showed extensive to near complete necrosis. Acrylic implants may lead to necrosis when injected directly in tumors. The necrotizing effect may extend beyond the limits of an implant in the case of PMMA. Such an extended effect of PMMA, when compared with NBCA, may be due to the variable toxicity of acrylic implants, including the different degrees of the exothermic reaction during polymerization.

Adenocarcinoma↗
PubMed1999

The pediatric disposable end-tidal carbon dioxide detector role in endotracheal intubation in newborns.

OBJECTIVE: To determine the practical value of the new pediatric disposable ETCO2 detector Pedi-CAP in verifying endotracheal tube placement in neonatal resuscitation. METHODS: Infants who required endotracheal intubation in the delivery room or the neonatal intensive care unit (NICU) were included in a prospective study in which the endotracheal tube placement was determined clinically and simultaneously by the Pedi-CAP and confirmed by chest radiograph. The Pedi-CAP and clinical evaluation determination times of the endotracheal tube placement were measured and compared. The accuracy and ease of the Pedi-CAP use were tested. RESULTS: Forty-five newborns (450 to 4620 gm) who needed endotracheal intubation were included in the study. Twenty-four (53.3%) were intubated in the delivery room and 21 (46.7%) in the NICU. The Pedi-CAP color indicator correlated with the clinical evaluation and radiograph findings of proper intubation in 30 of 33 patients (sensitivity 91%, specificity 100%, positive predictive value 100%, and negative predictive value 80%). There were three false-negative results in patients with severe cardiorespiratory depression. The Pedi-CAP color indicator correlated with the clinical evaluation for the ET-tube being in the esophagus in 12 of 12 patients (sensitivity, specificity, and positive and negative predictive value were all 100%). The time required to determine the tube position by clinical evaluation was 0 to 90 seconds (mean = 39.7 seconds; SD +/- 15.3 seconds). The time required with the disposable ETCO2 detector was 4 to 12 seconds (mean = 8.1 seconds; SD +/- 2.9 seconds; p < 0.001). CONCLUSION: The use of a disposable pediatric endotracheal CO2 detector significantly reduces the time spent in verifying the endotracheal tube position (trachea versus esophagus) in newborns, including premature babies with body weight < 1000 gm. This is of particular benefit to babies who are erroneously intubated in the esophagus, because using the device allows much faster detection of this problem and much earlier reintubation.

Carbon Dioxide↗
PubMed1999

Twinkling artifact on intracerebral color Doppler sonography.

Transcranial Doppler sonography shows potential as a noninvasive technique for long-term follow-up of treated intracranial saccular aneurysms. This technical note describes a color Doppler artifact related to microcoil architecture that might represent a potential pitfall in transcranial Doppler sonographic evaluation of aneurysmal cavity thrombosis, since it may be wrongly interpreted as residual flow or aneurysmal cavity recanalization.

Angiography, Digital Subtraction↗
PubMed1998

Complications of carotid angioplasty and stenting.

The authors report the complications that occurred in their experience with performing recanalization procedures in the internal carotid artery and present their treatment strategies. The complications can be classified into those that were periprocedural and those that were postprocedural. The former include complications related to the vascular-approach access site of and those associated with the dilation and stenting procedure. Other complications observed included embolic events, dissection, vascular spasm, bradycardia, inappropriate dilation, occlusion of the external carotid artery, and rare, unusual complications such as the occurrence of iatrogenic cavernous carotid fistula. Postprocedure complications occurred in the hours and days following the procedure in the form of embolic and occlusive events, and hypotension and bradycardia were seen as late complications in the months following the procedure. The authors discuss how such complications occur and provide suggestions on how to avoid them. The role of stent placement and the potential use of protective devices are explored. Overall, adequate use of currently available systems allows for safe application of endovascular treatment techniques that avoid altogether or treat these potential complications. A reduced incidence of complications related to the initial individual learning curve may be obtained with preclinical training, in which use of invitro models should be considered. Surgical standby no longer seems required; however, early posttreatment surveillance in intensive care unit is mandatory to avoid the remaining primary complications.

Journal Article↗
PubMed1998

Behavioral treatment of pulsatile tinnitus and headache following traumatic head injury. Objective polygraphic assessment of change.

Pulsatile tinnitus is a disorder that can be extremely disabling. Nonetheless, it has not been well-researched in the fields of psychology or behavioral therapy. This article describes the evaluation and behavioral treatment of a gentleman with pulsatile tinnitus. The evaluation included polygraphic assessment of vasomotor and electromyographic function both before and after treatment. The results show that the combination of lifestyle modifications and specific behavioral interventions were successful in modifying not only self-report indices of functioning, but also the underlying physiology related to the disorder. The potential role of the various treatment components and the value of including polygraphic assessment for informing treatment and evaluating outcome are discussed.

Adult↗