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Biomedical subjects

M A Germain

Publications and source records attributed to M A Germain.

68 records · Page 4Linked to original sources
PubMed1985

The induction of microphthalmia, encephalocele, and other head defects following hyperthermia during the gastrulation process in the rat.

The aim of this study was to ascertain whether there is a period during early embryonic development of the rat that is particularly sensitive to hyperthermia. Pregnant Sprague-Dawley rats were partially immersed in a water bath at 43.5 degrees C until their core temperatures, monitored by a rectal thermistor probe, were elevated to 43.5 degrees C. The procedure was repeated 6 hours later. The regimen of two heatings was performed over a range of development from early gastrulation (8 days 18 hours) to about the 12 somite stage (10 days 18 hours). The rats were killed on days 17-19 and the fetuses were examined. Each group contained a minimum of five litters. The main teratogenic effect of the hyperthermia was the induction of one or more head defects, notably microphthalmia, encephalocele (either a single, large, parietal encephalocele or multiple small protuberances), and maxillary hypoplasia. Microphthalmia was the most common defect with approximately 90% of surviving fetuses having small eyes when heating occurred between 9 days 6 hours and 10 days 0 hours (9.06 and 10.00). Encephaloceles were induced by heating between 9.00 and 10.00 with a peak sensitivity between 9.12 and 9.18 when 57% of surviving fetuses were affected. Maxillary hypoplasia resulted from heating between 9.06 and 10.06 with up to 20% of surviving fetuses being affected. Control rats were exposed to the same experimental procedure in a water bath at 38 degrees C on 9.12 and 9.18, the gestational time most sensitive to hyperthermia induced malformations. There were no abnormal fetuses in the controls. The critical period identified spans 9 days 6 hours to 10 days 0 hours gestational age. In developmental terms this includes a large proportion of the gastrulation process.

Animals↗
PubMed1985

Hyperthermia as a teratogen: parameters determining hyperthermia-induced head defects in the rat.

This study determined the relationship between the duration and extent of temperature elevation, during a critical period of rat embryonic development, and the induction of congenital malformations. Pregnant Sprague-Dawley rats, at 9 days 12 hours gestation (gastrulation stage), were partially immersed in a water bath until their core temperature, monitored by a rectal thermistor probe, was elevated to a nominated temperature. Seven temperatures were tested from 40.5 degrees C to 43.5 degrees C, elevations of 2.0-5.0 degrees C in core temperature. Various durations at each of these temperatures were tested for potential teratogenicity. A single elevation of 5.0 degrees C or 4.5 degrees C needed only a "spike" in duration to be teratogenic, 4.0 degrees C was teratogenic within 5 minutes, 3.5 degrees C within 10 minutes, 3.0 degrees C within 20 minutes, and 2.5 degrees C within 1 hour. An elevation of 2.0 degrees C for 8 hours was not teratogenic. Microphthalmia was the most common malformation at all teratogenic temperatures and was frequently the only malformation seen at the shortest time exposure for a particular temperature. Encephalocele, facial clefting, and maxillary hypoplasia were the other frequently seen malformations. Five control rats were placed in the water bath for 2 hours at 38 degrees C so that their core temperature was not elevated. All the control fetuses were normal. An elevation of 2.5 degrees C for 1 hour was the threshold combination for teratogenesis. As the temperature increased above a 2.5 degrees C elevation the necessary duration of exposure for teratogenesis decreased.

Animals↗
PubMed1984

Alcohol and congenital heart defects: an experimental study in mice.

Pregnant mice were exposed to a single dose of alcohol (0.03 ml of 25% alcohol X g-1 mouse) or two doses (2 X 0.015 ml of 25% alcohol X g-1 mouse) 4 h apart, by intraperitoneal injection or by gavage, on days 7, 8, 9 or 10 of gestation. The mice were killed on the day before term and the fetuses examined for heart defects. Alcohol exposure on day 8, 9 or 10 of gestation caused a high incidence of ventricular septal defects (60%, 75% and 15% respectively). Defects of both the membranous and muscular parts of the septum were seen as well as more complex ventricular septal defects involving the great vessels. Day 7 was resistant to the induction of heart defects. This study has demonstrated that a relatively short exposure to high doses of alcohol during pregnancy in mice can cause congenital heart defects. This has important implications both as a possible cause of congenital heart anomalies in humans and for the counselling of mothers of affected children.

Abnormalities, Drug-Induced↗
PubMed1980

[Internal thoracic vessels: importance in microsurgery].

The internal thoracic vessels were studied in seventy adult fresh corpses. The left and right vessels were studied so as to precise symmetry relating to the different characters. After injection of coloured latex, the arteries and veins were skeletonized. The origin, the caliber, the length, the connections with the sternal side, the ending were specified. The origin and the ending of these vessels are variable. A statistical study specifies these measures. In the second intercosal space a great contancy of these vessels was observed which was confirmed by angiography. They are used at this level to revascularize the subcutaneous esophagoplasties. The internal thoracic artery can be skeletonized by a right thoracotomy and allowed to revascularize a free jejunal graft for reconstruction of the upper thoracic esophagus.

Adult↗
PubMed1980

[Free omental autografts revascularized by microsurgery (author's transl)].

The greater omentum is good plastic material and supplies richly vascularized connective tissue for transplants. Some superficial and deep lesions of the soft tissues require extensive excision, and in favorable cases it is possible to use the greater omentum pedicled as described by Kiricuta. Two such cases are reported. In other cases a free transplant of omentum revascularized by microsurgical methods has to be used. This procedure was employed in ten patients and allowed repair of lesions with wide or deep loss of tissue under excellent conditions. An intermediate saphenous graft was necessary in one case. A dermoepidermal graft was applied at the same time in order to obtain results more rapidly. Progress made in microsurgical techniques has allowed omentum revascularization to be carried out under much safer conditions and this procedure should be employed more frequently.

Adolescent↗
PubMed1980

[Primary sclérosing cholangitis (author's transl)].

Primary sclerosing cholangitis is a rare affection. Two characteristic cases are described. A total of 80 cases have been reported in the published literature, and lesions are found varying from lacalized to diffuse forms. The affection is often associated with other disorders, especially hemorrhagic ulcerative rectocolitis, suggesting an auto-immune pathogenicity. Treatment is mainly surgical and consists, in the localized forms, of complete excision whenever possible and a by-pass operation. The diffuse forms, which are difficult to treat by surgicall methods, have a poorer prognosis and usually progress towards secondary biliary cirrhosis.

Adult↗
PubMedDate not supplied

[Carcinoma of the hypopharynx: reconstruction of the pharyngo-esophageal tract after circular pharyngectomy by the transplantation of a U-shaped jejunal loop to the neck].

Reconstruction of the oro- and hypopharynx has specific difficulties duo to their wide diameters. Thirteen patients underwent reconstruction with a free U-shaped jejunal transplant, after circular pharyngo-laryngectomy for hypopharyngeal cancer invading the oropharynx. This transplant included a side-to-side anastomosis between the two limbs of the jejunal loop and allowed reconstruction of the upper digestive tract after wide carcinologic resection of the pharynx. The U-shaped jejunal transplant facilitated the upper anastomosis, especially the upper part where the resection involved the oropharynx. It formed a reservoir behind the tongue and avoided nasal reflux. Best indication are large resections involving the oropharynx.

Aged↗
PubMedDate not supplied

The internal cavoatrial derivation for temporary vascular exclusion of the liver in the dog.

Vascular exclusion of the liver by clamping the hepatic pedicle and inserting an internal cavoatrial shunt allows bloodless hepatic surgery to be performed. The internal cavoatrial shunt performed on 30 dogs was studied to define its optimal hemodynamic characteristics. The internal diameter should measure half the caliber of the inferior vena cava and the total surface of the holes allowing blood flow to the shunt must be three times the internal caliber of the shunt. The aortic clamping associated with the clamping of the hepatic pedicle and the insertion of the internal cavoatrial shunt considerably diminishes the arterial blood pressure variations resulting from the splanchnic stasis. Administration of methylprednisolone (30 mg/kg) at the beginning of the experiment also plays a role in preventing alterations in the small intestine.

Animals↗
PubMedDate not supplied

[Salvage esophagoplasty using free jejunal transplant after repeated failure of other esophagoplasties. 25 cases].

Salvage oesophagoplasty using a free jejunal transplant is the ultimate reconstruction possible after repeated failures using the classic procedures of oesophagoplasty. The free jejunal transplant appears to be the best choice. Twenty-five free jejunal transplants were performed by the same surgeon for such reconstructions including 13 cases involving benign lesions and 12 cases of cancer. There were no post-operative death and none of the transplantations was a complete failure although three cases of stenosis and fistulization occurred. Several recommendations can be made: save the existing digestive tract, redissect the residual digestive plasty and pull it up. The residual digestive flap can be examined by opacification or endoscopically in order to evaluate its length. An arteriography of the pediculated plasty gives information on its vascularization. A free jejunal graft can safely cover 25 to 30 cm. When possible, residual plasties should be positioned subcutaneously. The reconstruction of the cervico-thoracic oesophagus usually requires a vascular bypass with a saphene graft. In difficult cases, it may be necessary to remove a part of the sternal manubrium and the head of the clavicular bone in order to avoid compressing the jejunal graft. When the length of the reconstruction is greater than 30 cm, a long jejunal transplant with two pedicules (1 pedicule revascularized from the cervical vessels and the other pedicule from the internal thoracic vessels) is needed. An alternative technique would be a free antebrachial flap (six cases operated with two post-operative deaths at 6 weeks and two fistulas).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Tumors of the mandible. Justification of a second reconstruction after recurrence on the first revascularized bone graft].

The use of free vascularized bone grafts for mandibular reconstruction has led to a consideration of the new entity of recurrent tumour on bone grafts. Exeresis of the mandible was performed in 4 patients with bone tumours: osteosarcoma 1, osteochondroma 1, carcinoma 1 and ameloblastoma 1. A free vascularized bone graft was used for the reconstruction. Tumours recurred with a delay of 10 to 18 months after the initial reconstruction. The frequency of tumoural recurrence can be measured in our series of 46 patients (24 with fibular grafts, 15 with scapular grafts, 4 with radius grafts and 3 with iliac bone grafts). Recurrence rate at our institution was 4.3%. The 2 other cases involved patients from other institutions. The main factor involved in tumoural recurrence is the aggressive nature of the primary tumours, even after extensive initial resection as performed in our patients. Free bone grafts were invaded as were neighbouring tissues. Secondary reconstruction of the mandible was performed in 3 cases with a fibula graft. In the fourth patient, no operation was possible due to the diffuse nature of the invasion and the poor status of the patient's vessels and general health. Local extension, and not the tumour histology, is the main factor in deciding upon reoperation. The explosive nature of recurrences is linked more to the aggressive character of the tumour than to the status of the revascularized free bone graft. Secondary reconstruction is justified after recurrence on bone grafts depending on the complexity of the major resection involving extensive tissue exeresis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

[Complete reconstruction of the nose using a prefabricated free forearm graft].

The aim of prefabricated free transplants is to create a composite graft including a vascular pedicle with artery and vein, a muscle and its nerve, cellular tissue, bony tissue, cartilage, periosteum, and skin with its sensory nerve. This composite transplant is entirely constructed and modelled around the chosen vascular pedicle beforehand. Once the various materials of the future graft are removed and put in contact with the vascular pedicle, the subsequent neovascularisation should nourish the different elements. The vasculonervous pedicle, with the graft, are transplanted five weeks after preconstruction, revascularized and reinnervated. With these free prefabricated transplants, graft tissue which does not exist in the organism can be created. Cosmetic sequellae can be avoided since the vascular pedicle is chosen beforehand. Ear-nose-throat and plastic surgeons have used local structural preconstruction for many years, especially for ear reconstruction. The work presented here has the original feature of revascularized free transplant. From 1988, we have performed two complete reconstructions of the nose using a free forearm transplant modelled into a nasal pyramid. The classical techniques could not be used. In the first case a radius strut was used to form the nasal crest. In the second a chondrocostal cartilage was used. Transplantation was performed five weeks after preconstruction. In both cases, transplant viability was excellent but the cosmetic and functional results were less than satisfactory and required reoperation.

Adult↗
PubMedDate not supplied

[Posterior pharyngectomy. Reconstruction using a free antebrachial transplant].

Cancers of the posterior wall of the oro or hypopharynx are rare and do not invade the larynx or the oesophageal orifice. Previously, these cancers were treated with radiotherapy alone, but since 1981 new techniques in reconstruction surgery have allowed a surgical approach. Cancerological non-mutilating exeresis is possible, but reconstruction is difficult since the flap must be very thin to allow normal food intake. In addition, flap reliability is extremely important due to the gravity of cervical salivary fistulation. We treated 15 patients with a lesion of the posterior wall of the pharynx using posterior pharyngectomy and reconstruction with a free antebrachial transplant which was revascularized and reinnervated. In two cases, the operation was performed in patients who had had previous radiotherapy. A branch of the external carotid and the internal jugular vein were used for vascular microanastomoses and reinnervation was obtained using the superficial cervical plexus. The transplant was placed over the prevertebral aponevrosis and sutured to the remaining pharyngeal mucosa. One postoperative death due to heart disease occurred at D + 11. All reconstructions were successful and two salivary fistulas on irradiated tissue closed spontaneously. Postoperative radiotherapy was performed in 11 cases (50-65 Gy) and was well tolerated. These results demonstrate that a highly flexible and thin free forearm transplant is perfectly adapted to reconstruction after posterior pharyngectomy. It is more reliable than local pediculated flaps.

Adult↗
PubMedDate not supplied

[Multiple free transplants in microsurgery for cervicofacial reconstruction].

Microsurgical techniques open the way for much creativity and originality for cervicofacial reconstruction and tumoral repair. Between 1976 and 1994, we performed 481 free transplants for cervico-facial reconstruction. A recently developed strategy has been the use of multiple free transplants, either simultaneously or successively. Between 1990 and 1994, we operated and reconstructed 9 patients using multiple free cervico-cephalic transplants after multitissular and agressive exeresis for tumoral or traumatic lesions. In 3 cases, the transplants were made simultaneously and in the 6 others successively. Three patients received 3 free transplants and 6 patients had 2. In 8 cases, each of the transplants was micro-anastomosed on different vessels. In one case, the two transplants were anastomosed in series, the most distal portion being connected to the most proximal portion (in comparison with the cervical vessels). One death occurred at 6 weeks due to infectious complications. The final result for the 8 other patients was good both morphologically and functionally. Indications for multiple free transplants include: complex tissue loss, multiple and massive tissue loss of the cervicocephalic region. This situation occurs particularly in case of voluminous tumours invading several structures, in multiple tumours and in firearm wounds. These series of patients allowed a definition of recommended techniques in case of difficulties in these very elaborate surgical procedures and confirmed that if the strategy is correctly planned, it is possible to greatly improve the quality of survival in these patients in terms of aesthetics, morphology and function.

Adolescent↗