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Biomedical subjects

L Morin

Publications and source records attributed to L Morin.

At least 37 records · Page 2Linked to original sources
PubMed1994

Prenatal diagnosis and management of fetal thoracic lesions.

There have been significant strides made during the last decade in understanding the natural history and pathophysiology of fetal thoracic lesions. Largely as a result of advances in prenatal ultrasound, we are not only able to diagnose these lesions and advise parents about prognosis, but also offer the possibility of fetal intervention for the most severely affected fetuses. However, large gaps remain in the current state of knowledge of fetal thoracic lesions. We are unable to accurately predict pulmonary hypoplasia, the most devastating consequence of fetal thoracic lesions. In lesions, such as CDH, the selection criteria for fetal intervention remain ill defined. Proof of the efficacy and superiority of fetal surgery over conventional postnatal therapies for diaphragmatic hernia await the results of prospective trials. Fetal surgery in lesions such as CCAM and BPS is currently reserved for only those fetuses with hydrops and a uniformly fatal outcome. Whether fetal surgery in these cases would be beneficial in the absence of hydrops is difficult to say especially given the possibility of spontaneous regression. During the next decade we anticipate continued growth in our understanding of these lesions, refinement in selection criteria for intervention, and advances in techniques for salvaging these severely compromised fetuses. The diagnosis and treatment of fetal thoracic lesions remains a formidable challenge, but one which can be met with cautious optimism, due to the availability of fetal interventions not previously available.

Bronchopulmonary Sequestration↗
PubMed1991

HLA DQB1*0301 allele is involved in the susceptibility to erythema multiforme.

Erythema multiforme (EM) is an acute, episodic inflammatory disorder of the skin and mucous membranes of various etiology that could be related to immunologic hypersensitivity response. EM has been previously reported to be associated with serologically defined HLA-DRw53 and DQw3 antigens. In this report, we reevaluate the role of HLA class II alleles in EM manifestations. With use of the polymerase chain reaction, followed by sequence-specific oligonucleotide hybridization, 35 unrelated Caucasian EM patients and 80 randomly selected healthy subjects were studied, and the DRB3, DRB4, DQA1, and DQB1 alleles were analyzed. The comparison of frequencies of these alleles indicates that (i) susceptibility to EM disease is more associated with the HLA-DQ than the HLA-DR subregions and (ii) that the DQB1*0301 is the most frequent allele among EM patients. Sixty-six percent of the patients had the DQB1*0301 allele compared to 31% of the controls (RR = 4.1; p less than 0.001). An even stronger DQB1*0301 association was found in the patient group with herpes-associated EM (76%; RR = 6.5; p less than 0.001). Our data demonstrate a clear association between an HLA-DQB1 allele and susceptibility to EM.

Adolescent↗
PubMed1990

A combination of HLA-DQ beta Asp57-negative and HLA DQ alpha Arg52 confers susceptibility to insulin-dependent diabetes mellitus.

Family and population studies indicate that predisposition to insulin-dependent (type I) diabetes mellitus (IDDM) is polygenic. It has been shown that the absence of the aspartic acid in position 57 (Asp57) of the DQ beta chain is positively correlated to IDDM. However, Asp57-negative haplotypes do not always confer susceptibility and conversely, some Asp57-positive haplotypes seem to be disease associated. It has been suggested that other HLA class II sequences, probably belonging to the HLA DQA1 gene, confer susceptibility to IDDM. This report, based on extensive oligonucleotide dot blot hybridization of PCR-amplified DQA1 and DQB1 genes, reinforces the importance of the Asp57-negative DQ beta chain, but also introduces the possibility that a DQ alpha chain bearing an arginine in position 52 (Arg52) confers susceptibility to IDDM. A molecular model of susceptibility to IDDM is proposed. This model strongly suggests that the disease susceptibility correlates quantitatively with the expression at the cell surface of a heterodimer, composed of a DQ alpha-chain bearing an Arg52 and a DQ beta chain lacking an Asp57. In view of the respective positions of the two residues and their charge, we might anticipate that both residues DQ beta Asp57 and DQ alpha Arg52 are critical for modulation of susceptibility, presumably via viral-antigenic peptide and/or autoantigen presentation.

Base Sequence↗
PubMed1990

HLA DQ alpha/beta molecule associated with the susceptibility to insulin-dependent diabetes mellitus. A model for HLA/autoimmune disease association.

We have proposed a molecular model of susceptibility to Insulin-Dependent Diabetes Mellitus (IDDM) based on the proportional expression at the cell surface of the following susceptible (S-S) HLA-DQ heterodimere composed of a chain DQ alpha Arg 52 positive (S) and a chain HLA-DQ beta Asp 57 negative (S). All other DQ alpha/beta chains associations are considered as protective molecules. This model allows a predictive scale of risk for the disease.

Alleles↗
PubMed1990

Typing for HLA DQ using oligonucleotidic probes.

We have typed 25 homozygous B lymphoblastoid cell lines, defined as reference panel during the Xth International Histocompatibility Workshop, using PCR (Polymerase Chain Reaction) and oligonucleotidic probes recognizing sequences of DQA and DQB genes. The polymorphism of 8 HLA-DQA1, and 12 DQB1 alleles is reported and the advantages of this technique are compared to that of other typing methods, currently used.

Cell Line↗
PubMed1988

Removal of the 33, 23 and 18 kDa extrinsic proteins of photosystem II by sulfite treatment at alkaline pH.

We found that sulfite incubation of photosystem II submembrane fractions can induce selective depletion of the 18, 23 and 33 kDa polypeptides of the PSII oxygen evolving complex. When the sulfite treatment was done at pH 8.0, the 18 and 23 kDa proteins were removed efficiently from the PSII oxygen evolving complex. Under the same conditions, the 33 kDa subunit remained bound (even when 2 M sodium sulfite was used). However, in more alkaline conditions (pH 9.8), we show extensive removal of the 33 kDa in the presence of a low sulfite concentration (50 mM). The different extraction affinity for the 18, 23 and 33 kDa of the photosystem II complex was interpreted to mean that the 33 kDa polypeptides are bound to photosystem II by both electrostatic and hydrogen bonding forces.

Chlorophyll↗
PubMed1988

Conscious-sedation analgesia during craniotomy for intractable epilepsy: a review of 354 consecutive cases.

The perioperative records of 354 consecutive patients undergoing craniotomy for surgical treatment of intractable epilepsy performed with conscious-sedation analgesia were reviewed retrospectively. There was no perioperative morbidity or mortality identified which could be attributed to the anaesthetic technique. The technique was not suitable for seven patients, in whom general anaesthesia was induced. The most frequent intraoperative problems were convulsions (16 per cent) and nausea and vomiting (eight per cent). Less frequent problems included excessive sedation (three per cent), "tight brain" (1.4 per cent) and local anaesthetic toxicity (two per cent). This study confirms that conscious-sedation analgesia provides suitable conditions for craniotomies when brain mapping is required.

Adolescent↗
PubMed1987

Outflow resistance measurement during infrainguinal arterial reconstructions: a reliable predictor of limb salvage.

Criteria for abandoning infrainguinal arterial reconstructions in favor of major amputations should include reliable predictors not only of graft patency, but more importantly, of limb salvage. To evaluate the efficacy of intraoperative outflow resistance measurements in predicting limb salvage after infrainguinal bypasses, we have reviewed 134 such operations (64 femoropopliteal and 70 femorodistal bypasses) performed for critical ischemia. Outflow resistance measurements were divided into quartiles for femoropopliteal bypasses (Group A 0.17 mm Hg/ml/min or less, Group B 0.18 to 0.24 mm Hg/ml/min, Group C 0.25 to 0.4 mm Hg/ml/min, and Group D greater than 0.4 mm Hg/ml/min) and femorodistal bypasses (Group A 0.4 mm Hg/ml/min or less, Group B 0.4 to 0.58 mm Hg/ml/min or less, Group C 0.6 to 1 mm Hg/ml/min, and Group D 1 mm Hg/ml/min or greater). One year limb salvage rates for patients who underwent femoropopliteal bypass were 95 percent, 92 percent, 87 percent, and 67 percent from the lowest to the highest quartile (difference not statistically significant), and for those who had femorodistal bypass, they were 51 percent, 75 percent, 48 percent, and 0, respectively (p less than 0.05). Interestingly, 12 month graft patency and limb salvage rates for patients who underwent femorodistal bypass with outflow resistances between 0.59 and 1 mm Hg/ml/min did not correlate well (22 percent and 48 percent, respectively), whereas for those with outflow resistance greater than 1 mm Hg/ml/min, they were 22 percent and 22 percent, respectively. Thus, measurement of intraoperative outflow resistance is a very accurate predictor of limb salvage after infrainguinal bypass operations.

Adult↗
PubMed1987

Intraoperative outflow resistance as a predictor of late patency of femoropopliteal and infrapopliteal arterial bypasses.

To evaluate the efficacy of intraoperative outflow resistance (OR) measurements in predicting late graft patency rates (PR) for femoropopliteal (FP) and femoroinfrapopliteal (FD) bypasses, we have reviewed 134 such cases performed during the past 3 years at our institution. Of these, 64 bypasses were FP (13 autogenous saphenous vein [ASV] and 51 polytetrafluoroethylene [PTFE]) and 70 were FD (43 ASV and 27 PTFE). Total and distal OR measurements (measured in millimeters of mercury per milliliter per minute) were divided into four groups each for all infrainguinal bypasses combined and for FP and FD bypasses separately. The relationship of PR to total and distal OR measurements were analyzed according to the product limit method. Overall 1- and 2-year PRs were 64% and 56%, respectively. For FP bypasses the same PRs were 78% and 67% whereas for FD bypasses, they were 52% and 45%, respectively. The 1-year PRs for FP and FD bypasses within each respective OR group were analyzed. For FP bypasses in the lowest to the highest total OR groups, the 1-year PRs were 86%, 75%, 78%, and 62% (NS), and for FD bypasses they were 72%, 89%, 23%, and 22% (p less than 0.001). Similar trends were observed when distal OR measurements were analyzed. For infrainguinal PTFE bypasses, both total and distal OR measurements were significant predictors of patency, whereas for those with ASV only distal OR measurements were predictive. These data reaffirm our early experience with OR measurements. Although a trend for predicting graft patency was noted for FP bypasses, OR measurements were highly predictive only for FD bypasses.

Adult↗
PubMed1984

Anaesthetic considerations in percutaneous radiofrequency coagulation of the Gasserian ganglion.

This study determined the cardiovascular effects of percutaneous radiofrequency coagulation of the Gasserian ganglion, performed under neuroleptanalgesia and intermittent ultrashort-acting barbiturate anaesthesia. Twelve ASA physical status class II patients were studied. Highly significant increases in mean heart rate and arterial blood pressure followed the insertion of the cannula electrode into the Gasserian ganglion (p less than 0.001). In six randomly assigned patients severe tachycardia and hypertension also accompanied the progress of the thermal lesion (p less than 0.0001). Three patients developed premature ventricular contractions, and two developed significant ST segment depression. Intravenous nitroglycerin, used during current generation, successfully controlled the hypertensive response in the other six patients. In percutaneous thermocoagulation of the Gasserian ganglion the patient's co-operation is essential. In addition to providing suitable operating conditions for both surgeons and patient, we should also be able to maintain normal and stable cardiovascular haemodynamics. Intravenous nitroglycerin used as an adjunct to light general anaesthesia safely maintained intraoperative normotension. It is also suggested that patients with coronary artery disease be adequately monitored and protected during the procedure.

Aged↗
PubMed1984

Quantitative assessment of outflow resistance in lower extremity arterial reconstructions.

Graft patency is thought to correlate with resistance in the runoff bed or outflow resistance. However, accurate measurement of this parameter has been difficult. A simple and reproducible method for direct measurement of outflow resistance following completion of the distal anastomosis of a bypass graft has been developed. This method employs injection of a fixed amount of normal saline through the proximal end of the graft and measurement of the resulting integrated pressure increment by an analog computer. Division of this pressure integral by the volume injected is a measure of the outflow resistance expressed in resistance units (mm Hg/ml/min). The median outflow resistance in 31 femoropopliteal bypasses was 0.29 units with a range of 0.08-1.38 units. The median outflow resistance in 33 femorodistal bypasses was 0.7 units with a range of 0.18-2.34 units. All bypasses with an outflow resistance of 1.1 units or less remained patent for 3 months. There were 51 grafts in this group (30 femoropopliteal; 21 femorodistal) and their outflow resistance ranged from 0.08 to 1.1 units. All bypasses with an outflow resistance of 1.2 units or higher thrombosed within the first postoperative month. There were 13 grafts in this group (1 femoropopliteal; 12 femorodistal) and their outflow resistance ranged from 1.2 to 2.38 units. Eight of the 13 grafts that failed originally were subjected to thrombectomy, which was uniformly unsuccessful. Although this method does not yet allow bypass surgery to be denied to any patient, it does define a group of patients in whom thrombectomy will not be effective and should not be attempted.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Components of outflow resistance and their correlation with graft patency in lower extremity arterial reconstructions.

We have used a simple reproducible method to measure total outflow resistance (OR) and its proximal and distal components in 101 bypasses (46 femoropopliteal [FP] and 55 femorodistal [FD]). All bypasses with a distal OR greater than 1.2 mm Hg/ml/min failed within 3 months and all with distal OR less than 1.2 mm Hg/ml/min remained patent for at least 3 months. To evaluate the contribution of vasospasm to OR and its role in graft failure, 60 bypasses (29 FP, 31 FD) had OR measurements before and after local infusion of papaverine hydrochloride (60 mg). Within 3 months, nine grafts (all FD) occluded and 51 remained patent. All nine failures had distal OR greater than 1.2 mm Hg/ml/min before papaverine infusion. After infusion, the mean percentage decrease in both total and distal OR for all grafts was 30% and 31%, respectively. However, there was no significant difference between these papaverine-induced decreases in OR and 3-month graft failure or success. Moreover, in three bypasses, even though papaverine lowered the distal OR from greater than 1.2 to less than 1.2 mm Hg/ml/min, early occlusion occurred. In six grafts (1 FP, 5 FD) when total and distal OR before and after papaverine was greater than 1.2 mm Hg/ml/min, the graft was extended to a second distal artery as a sequential bypass. These six grafts have remained patent over 3 months. Thus measurement of OR and particularly distal OR is a most accurate predictor of early graft success or failure. Pharmacologic manipulation does not enhance the predictive value of the OR measurement. OR measurements also help to select those FD bypass cases in which extension to a second distal artery as a sequential bypass improves patency.

Aged↗