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Biomedical subjects

J M Michel

Publications and source records attributed to J M Michel.

At least 19 recordsLinked to original sources

Video-assisted neck exploration for primary and secondary hyperparathyroidism: initial experience.

BACKGROUND: Minimally invasive surgery (MIS) for primary hyperparathyroidism includes unilateral neck exploration, access via a totally endoscopic approach, and access via a video-assisted procedure. We report herein our initial experience with the video-assisted neck exploration procedure for primary (PHPT) and secondary hyperparathyroidism (SHPT). METHODS: Between June 1999 and May 2000, 35 patients were selected for PHPT (n = 25) and SHPT (n = 10). In all cases, video-assisted neck exploration was performed under general anesthesia, leading to selective adenoma removal in PHPT or subtotal parathyroid resection in SHPT. Patient selection was based on the preoperative localization studies (ultrasonography and sestamibi scintigraphy). RESULTS: Five of the 25 patients operated on for PHPT (20%) and three of the 10 patients who underwent surgery for SHPT (30 %) were converted to a conventional surgical technique. The mean operative times in PHPT and SHPT were 48.9 +/- 18.7 min and 136.8 +/- 18.7 min, respectively. The recurrent laryngeal nerve was identified in 45% of the patients. The median size and weight of the resected parathyroid glands were 1.8 cm (range, 0.9-2.5) and 1 g (range, 0.5-7), respectively. The length of skin incision was 24 +/- 1.2 mm. All but one patient are currently cured, with a median follow-up of 6 months (range, 2-13). Postoperative complications included hematoma and transient hoarseness in one patient each (2.85%). The median pain intensity, based on the visual analogue scale (VAS) method, as measured at postoperative day 1 was 0.5 (range, 0-3.6). In the PHPT group, the postoperative hospital stay was

Adult↗

Bile exposure of the denervated stomach as an esophageal substitute.

BACKGROUND: Both the supine position and the existence of a gastric drainage procedure are suspected to promote reflux of duodenal juice into the denervated intrathoracic stomach. Erythromycin has been shown to weaken pyloric resistance to gastric outflow and to enhance antral motility, gastric emptying, and gallbladder contractility. METHODS: The presence of bile in the gastric transplant of 79 patients was monitored over a 24-hour period with use of the Bilitec 2000 optoelectronic device 3 to 195 months after subtotal esophagectomy. Ten patients were reinvestigated after a 3-year period. Five groups were studied: group I: n = 12, no gastric drainage, never given erythromycin, group 2: n = 40, gastric drainage, never given erythromycin, group 3: n = 7, no gastric drainage, given erythromycin, group 4: n = 13, gastric drainage, given erythromycin, and group 5: n = 7, no longer given erythromycin (with or without gastric drainage). The percentage of time gastric bile absorbance was more than 0.25 was calculated for the total, supine, and upright periods of recording in reference to data from 25 healthy volunteers. RESULTS: The Bilitec test was pathologic in 9 of the 12 patients of group 1 whereas it was normal in three. Gastric exposure to bile was longer in group I patients than in controls for the total (p = 0.012) and supine (0.036) periods, but the difference did not reach statistical significance for the upright period (p = 0.080). Bile exposure in group 4 did not significantly differ from controls (total: p = 0.701; supine: p = 0.124; upright: p = 0.712). Bile exposure for the total period did not significantly differ whether patients were taking erythromycin or the drug had been discontinued at the time of the study (p = 0.234); and it tended to decrease with time in patients investigated twice (p = 0.046). CONCLUSIONS: Gastric exposure to bile after truncal vagotomy and transposition of the stomach up to the neck is pathologic in three quarters of patients. It is more marked in the supine than in the upright position and tends to decrease with time. The addition of a gastric drainage procedure in combination with erythromycin therapy tends to normalize gastric exposure to bile. The effects of erythromycin may persist after discontinuation of the drug.

Adult↗

[Managing chronic wounds. Knowledge and practice of nurses].

BACKGROUND: Recommendations on chronic wound management have greatly evolved during the last years. Practice in the medical units of the Civil Hospital of Colmar (France) appears to controversy these recommendations. Since nurses have a central place in such cares, we conducted a management audit among those working in different departments, before organising an educational program. METHODS: One hundred and ten nurses (20 p. 100), randomly selected among the 546 concerned by chronic wounds working in the hospital were invited to participate in this audit composed of 23 questions. RESULTS: Participation rate was 72 p. 100. Response rates were higher than 80 p. 100 for 18 of 23 questions. The percentages below are those of the expressed answers. For 58 p. 100 of nurses executing the care after medical prescription, 31 p. 100 did so without medical advice and 11 p. 100 in collaboration with a doctor. Five and 14 p. 100 respectively knew all the classical clinical characteristics of venous and arterial leg ulcers. Some important risk factors for pressure sores were not well known, and only 15 p. 100 of nurses regularly used an evaluation scale of this risk. The massage-kneading of a stage I pressure ulcer was practiced by 49 p. 100 of nurses. Depending on the questions, 64 to 82 p. 100 of them routinely used antiseptics, and 82 p. 100 thought it was more important than compression for the healing of a venous leg ulcer. In more than one third of the answers, the dressing of a chronic wound was described as sterile. Finally, if an average knowledge of hydrocolloids was observed, there was little on alginates, foams and hydrogels, with a majority of nurses avoiding to answer these questions. COMMENTS: Although important is the management of chronic wounds, basic knowledge was insufficient to hope for the nurses' collaboration. Prevention policy of pressure sores was not optimal. There were discrepancies between local practices and actual knowledge. Knowledge of new dressings was inadequate, and there was a risk for limited clinical benefit. We believe the results would have been similar if the audit had conducted among the doctors. Hense, a vast educational program has been initiated.

Chronic Disease↗

Analysis of genes involved in 6-deoxyhexose biosynthesis and transfer in Saccharopolyspora erythraea.

Glycosylation represents an attractive target for protein engineering of novel antibiotics, because specific attachment of one or more deoxysugars is required for the bioactivity of many antibiotic and antitumour polyketides. However, proper assessment of the potential of these enzymes for such combinatorial biosynthesis requires both more precise information on the enzymology of the pathways and also improved Escherichia coli-actinomycete shuttle vectors. New replicative vectors have been constructed and used to express independently the dnmU gene of Streptomyces peucetius and the eryBVII gene of Saccharopolyspora erythraea in an eryBVII deletion mutant of Sac. erythraea. Production of erythromycin A was obtained in both cases, showing that both proteins serve analogous functions in the biosynthetic pathways to dTDP-L-daunosamine and dTDP-L-mycarose, respectively. Over-expression of both proteins was also obtained in S. lividans, paving the way for protein purification and in vitro monitoring of enzyme activity. In a further set of experiments, the putative desosaminyltransferase of Sac. erythraea, EryCIII, was expressed in the picromycin producer Streptomyces sp. 20032, which also synthesises dTDP-D-desosamine. The substrate 3-alpha-mycarosylerythronolide B used for hybrid biosynthesis was found to be glycosylated to produce erythromycin D only when recombinant EryCIII was present, directly confirming the enzymatic role of EryCIII. This convenient plasmid expression system can be readily adapted to study the directed evolution of recombinant glycosyltransferases.

Anti-Bacterial Agents↗

A simple method to transfer plasmid DNA into neuronal primary cultures: functional expression of the mGlu5 receptor in cerebellar granule cells.

We describe a method to transfer cDNA into neuronal primary cultures with a commercialised cationic lipid, Transfast. Cultures were transfected at a rate of about 5% with green fluorescent protein (GFP) cDNA. Comparing Transfast to other transfection reagents, we found this compound to be the most efficient. GFP-transfected mouse cerebellar granule cells displayed normal whole-cell voltage-sensitive and unitary big K+ channel currents. We also used this transfection method with success to transfer GFP cDNA into primary cultures of striatum and colliculus. Transfast was then used to cotransfect cultured cerebellar cells with GFP cDNA, in conjunction with cDNA coding for the metabotropic glutamate receptor type 5 (mGlu5 receptor). Ninety percent of the cells expressing GFP also expressed mGlu5 receptor. Though neurones were best transfected one day after plating, they still expressed both GFP and mGlu5 receptor proteins 2 weeks after plating, i.e. after full differentiation. A functional test of the expressed mGlu5 receptor was thus performed in GFP-transfected neurones. Stimulation of mGlu5 receptor induced single big K+ channel activity, as it was the case for the native mGlu1 receptor. This indicated that the transfected mGlu5 receptor plasmid was functionally expressed and that both mGlu1 and mGlu5 receptors may share common coupling mechanisms to big K+ channels in neurones.

Animals↗

[Primary surgical care of pelvic fractures associated with perineal laceration].

Unstable fractures of the pelvic ring, associated to perineal lacerations are severe injuries occurring during high-energy trauma. High rates of septic complications and mortality have been reported with these injuries. Current treatment guidelines, while dealing with open pelvic fractures or dislocations are discussed, based on a current review of the literature and on our local experience. At our institution, 55 unstable type B or C fractures of the pelvic ring were treated by osteosynthesis between 1991 and 1997. Of these, 11 patients presented with an associated perineal laceration (20%). Simultaneously to the immediate pelvic ring fixation, a diversion colostomy was performed in all these patients. Repeated wound debridements and wide spectrum antibioprophylaxis were associated. Of these 11 patients presenting an open pelvic fracture, only one died of pelvic sepsis at three weeks. 10 patients survived (91%) and went on to bony union, without any local infectious complications. Aggressive multidisciplinary initial surgical management is a rule when dealing with this type of injuries, immediate colostomy and careful wound debridement must be associated to the initial osteosynthesis.

Adult↗

Surgical treatment of thyroid papillary carcinoma: current controversies.

Papillary cancer is the most frequent thyroid cancer occurring in all age groups with a good prognosis. Surgery is commonly recognized as the primary treatment of PC, but controversy concerning the type of resection continues. We are still waiting for the best predictors of tumor aggressiveness which would help us to select patients for the type of surgery according to the tumor prognosis. We currently recommend total thyroidectomy in all cases leading to eradicate all tumoral tissue specially in multicentric disease, to optimize the effect of postoperative Iodine-131 therapy and to allow thyroglobulin levels to be reliably used as a marker of recurrence. We advocate lymphnode dissection only if chain nodes are palpable. Total thyroidectomy should be made by experienced surgeon in order to minimize post-operative morbidity.

Biopsy, Needle↗

[Left colectomy with immediate anastomosis in emergency surgery].

PURPOSE OF THE STUDY: A retrospective study of our experience with one-stage left colectomy for acute diverticulitis and obstruction with a review of the literature to more clearly define the indications of this procedure. PATIENTS AND METHODS: 30 patients were operated for acute diverticulitis (group 1) and 47 for obstruction (group 2). Only 7 patients (23%) of group 1 had an intraoperative colonic lavage while this was performed for all the patients of group 2. RESULTS: The postoperative morbidity and mortality for the patients of group 1 and 2 were 37 and 28%, and 7 and 11% respectively. None of the patients of group 1 had clinical anastomotic leak, while this occurred in 2 patients (4%) of group 2. The mean hospital stay was 26 days for patients of group 1 and 17 days for patients of group 2. CONCLUSIONS: Bowel obstruction should be treated by one-stage left colectomy and intraoperative colonic lavage for patients with low anaesthetic risks (ASA 1 and 2). Immediate anastomosis protected by colostomy or ileostomy could be proposed for patients with an intermediate risk (ASA 3). Patients with acute diverticulitis and a localized abscess or peritonitis should be treated with one-stage colectomy; an immediate protected anastomosis could be performed in patients with generalized purulent peritonitis while a Hartmann's type colectomy should be the reasonable option for fecal generalized peritonitis. Intraoperative colonic lavage does not seem mandatory.

Acute Disease↗

cAMP-mediated long-term modulation of voltage-dependent K+ channels in cultured colliculi neurons.

Previously, we have described prolonged cAMP-induced inhibition of a K+ current in cultured colliculi neurons. The aim of the present study was to characterize the channel responsible for this cAMP-dependent effect. We detected the presence of a non-inactivating voltage-dependent 16-pS K+ channel that displayed long-lasting inhibition upon a brief application of cAMP and greater sensitivity to tetraethylammonium than to 4-aminopyridine. In addition to this channel, colliculi neurons express two other voltage-sensitive, non-inactivating K+ channels (8 and 49 pS) whose activity is facilitated by a brief application of cAMP, the effect of which is also long-lasting. These results suggest the presence of common sustained cAMP-dependent processes responsible for both up- and down-regulation of these channels in the neurons studied. They indicate that the 16-pS, but not the 8-pS or the 49-pS channels, participates in the cAMP-inhibited macroscopic K+ current.

4-Aminopyridine↗

Targeted gene inactivation for the elucidation of deoxysugar biosynthesis in the erythromycin producer Saccharopolyspora erythraea.

The production of erythromycin A by Saccharopolyspora erythraea requires the synthesis of dTDP-D-desosamine and dTDP-L-mycarose, which serve as substrates for the transfer of the two sugar residues onto the macrolactone ring. The enzymatic activities involved in this process are largely encoded within the ery gene cluster, by two sets of genes flanking the eryA locus that encodes the polyketide synthase. We report here the nucleotide sequence of three such ORFs located immediately downstream of eryA, ORFs 7, 8 and 9. Chromosomal mutants carrying a deletion either in ORF7 or in one of the previously sequenced ORFs 13 and 14 have been constructed and shown to accumulate erythronolide B, as expected for eryB mutants. Similarly, chromosomal mutants carrying a deletion in either ORF8, ORF9, or one of the previously sequenced ORFs 17 and 18 have been constructed and shown to accumulate 3-alpha-mycarosyl erythronolide B, as expected for eryC mutants. The ORF13 (eryBIV), ORF17 (eryCIV) and ORF7 (eryBII) mutants also synthesised small amounts of macrolide shunt metabolites, as shown by mass spectrometry. These results considerably strengthen previous tentative proposals for the pathways for the biosynthesis of dTDP-D-desosamine and dTDP-L-mycarose in Sac. erythraea and reveal that at least some of these enzymes can accommodate alternative substrates.

Amino Acid Sequence↗

Analysis of a Streptomyces antibioticus chromosomal region involved in oleandomycin biosynthesis, which encodes two glycosyltransferases responsible for glycosylation of the macrolactone ring.

A 6-kb region from the chromosome of Streptomyces antibioticus, an oleandomycin producer, was cloned and sequenced. This region was located between the 3' end of the gene encoding the third subunit of the oleandomycin type I polyketide synthase and the oleP and oleB genes, which encode a cytochrome P450 monooxygenase and an oleandomycin resistance gene, respectively. Analysis of the nucleotide sequence revealed the presence of five genes encoding a cytochrome P450-like protein (oleP1), two glycosyltransferases (oleG1 and oleG2) involved in the transfer of the two 6-deoxysugars (L-oleandrose and D-desosamine) to the oleandomycin macrolactone ring, a methyltransferase (oleM1), and a gene (oleY) of unknown function. Insertional inactivation of this region by gene disruption generated an oleandomycin non-producing mutant which accumulated a compound that, according to mass spectrometry analysis, could correspond to the oleandomycin macrolactone ring (oleandolide), suggesting that the mutation affects oleandrosyl glycosyltransferase.

Amino Acid Sequence↗

Modulation of big K+ channel activity by ryanodine receptors and L-type Ca2+ channels in neurons.

As metabotropic glutamate receptor type 1 (mGluR1) is known to couple L-type Ca2+ channels and ryanodine receptors (RyR, Chavis et al., 1996) in cerebellar granule cells, we examined if such a coupling could activate a Ca2+-sensitive K+ channel, the big K+ (BK) channel, in cultured cerebellar granule cells. We observed that (+/-)-1-amino-cyclopentane-trans-1,3-dicarboxylic acid (t-ACPD) and quisqualate (QA) stimulated the activity of BK channels. On the other hand, (2S, 3S, 4S)-alpha-carboxycyclopropyl-glycine (L-CCG-I) and L-(+)-2-amino-4-phosphonobutyrate (L-AP4) had no effect on BK channels, indicating a specific activation by group I mGluRs. Group I mGluRs stimulation of the basal BK channel activity was mimicked by caffeine and both effects were blocked by ryanodine and nifedipine. Interestingly, carbachol stimulated BK channel activity but through a pertussis toxin (PTX)-sensitive pathway that was independent of L-type Ca2+ channel activity. Our report indicates that unlike the muscarinic receptors, group I mGluRs activate BK channels by mobilizing an additional pathway involving RyR and L-type Ca2+ channels.

Animals↗

[Traumatic lesions of the anorectum].

Injuries of the colon and rectum are common surgical problems. Lesions can be classified into four groups according to the site of damage and the presence of sphincter tears: 1. intraperitoneal perforation without sphincter damage 2. intraperitoneal perforation with sphincter damage 3. extraperitoneal perforation without sphincter damage 4. extraperitoneal perforation with sphincter damage From 1990 to 1998, 11 patients, 7 males and 4 females presenting an anal and/or rectal trauma were admitted in Geneva University Hospital. 8 patients were admitted as an emergency, the 3 others had been transferred to correct an incontinent post traumatic pathology. No mortality. A terminal colostomy was performed in all patients with intraperitoneal injury and in 5 patients with combined extraperitoneal and anal sphincter injury. All sphincter lesions were sutured as an emergency (6 cases). In 3 patients we performed an overlapping sphincteroplasty. 2 patients with persisting incontinence were cured by a dynamic stimulated graciloplasty. The choice of treatment of anorectal trauma includes broad spectrum antibiotherapy, cleaning of the rectum, sphincter repair. A terminal diverting colostomy and laparotomy must be achieved in case of intraperitoneal injury, large extraperitoneal lesion, severe perineal laceration with or without pelvic fracture.

Anal Canal↗

Metabotropic glutamate receptors in the rat nucleus accumbens.

The effects of glutamate metabotropic receptors (mGluRs) on excitatory transmission in the nucleus accumbens were investigated using electrophysiological techniques in rat nucleus accumbens slices. The broad-spectrum mGluR agonist (1S,3R)-1-aminocyclopentyl-1,3-dicarboxylate, the mGluR group 2 selective agonists (S)-4-carboxy-3-hydroxyphenylglycine, (1S,3S)-ACPD) and (2S,1'S,2'S)-2-(2'-carboxycyclopropyl)glycine (L-CCG1), and the mGluR group 3 specific agonist L-2-amino-4-phosphonobutyrate (L-AP4) all reversibly inhibited evoked excitatory synaptic responses. The specific group 1 mGluR agonist (R,S)-3,5-dihydroxyphenylglycine [(R,S)-DHPG] did not depress transmission. Dose-response curves showed that the rank order of agonist potencies was: L-CCG1 > L-AP4 > (1S,3S)-ACPD. Group 2 and 3 mGluRs inhibited transmission via a presynaptic mechanism, as they increased paired-pulse facilitation, decreased the frequency of miniature excitatory postsynaptic currents and had no effect on their amplitude. The mGluRs did not inhibit transmitter release by reducing voltage-dependent Ca2+ currents through N- or P-type Ca2+ channels, as inhibition persisted in the presence of omega-conotoxin-GVIA or omega-Aga-IVA. The depression induced by mGluRs was not affected by specific antagonists of dopamine D1, GABA-B or adenosine A1 receptors, indicating direct effects. Finally, (R,S)-DHPG specifically blocked the postsynaptic afterhyperpolarization current (I(AHP)). Our results represent the first direct demonstration of functional mGluRs in the nucleus accumbens of the rat.

Adenosine↗

Swan-Ganz catheter induced pulmonary artery perforation during cardiac surgery concerning two cases.

Two case reports describing patients having cardiac operations under extra corporeal circulation are presented. At the completion of the operation, a massive hemoptysis occurred in both patients after a Swan-Ganz catheter had perforated the pulmonary artery. A hemostasis lobectomy was then immediately required. The immediate and long term prognosis seems satisfactory. This is an unusual but serious complication. The incidence of this complication varies between 0.06 and 0.2%. The more frequently related risk factors include people over the age of 60, pulmonary artery hypertension, anticoagulant therapy, hypothermia and manipulation of the heart by the surgeon. When this accident occurs, many authors suspect the balloon. An early diagnosis is essential in the case of a major or even a minor hemoptysis, because this complication may be a lethal one as the mortality rate may reach 50%. According to us, the appropriate therapy which would reduce this mortality is a surgical one (hemostasis lobectomy).

Aged↗