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Biomedical subjects

M A Shermak

Publications and source records attributed to M A Shermak.

9 recordsLinked to original sources
PubMed2000

Reconstruction of complex cranial wounds with demineralized bone matrix and bilayer artificial skin.

Complex wounds involving loss of both cranium and scalp are difficult to reconstruct. Current solutions include both autogenous and alloplastic materials. Tissue engineering provides interesting alternatives for reconstruction of missing bone and soft tissue. Demineralized bone matrix and Integra, artificial bilayer skin substitute, have been used successfully to reconstruct bone and skin as isolated defects, but never in combination. This study investigates the possibility of using demineralized bone matrix in a gel carrier and Integra for combined cranial and scalp defects. The study was divided into two parts. In the first, demineralized bone matrix in the forms of Grafton Flex (n = 12) and Grafton putty (n = 12) was used to reconstruct 15-mm critical size cranial defects in female adult New Zealand White rabbits. In the control group (n = 6), the defect was left empty. The second part of the study investigated the use of Integra and Grafton Flex to reconstruct a 15-mm cranial defect with an overlying full-thickness scalp defect (n = 6). The first study revealed bony healing of the critical-size cranial defect with demineralized bone matrix. The second study demonstrated successful reconstitution of scalp and cranium with both demineralized bone matrix and Integra. We conclude that complex cranial defects involving bone and soft tissue may be successfully reconstructed with their tissue-engineered substrates, demineralized bone matrix (Grafton) and Integra artificial skin.

Absorptiometry, Photon↗
PubMed1998

Fixation of the craniofacial skeleton with butyl-2-cyanoacrylate and its effects on histotoxicity and healing.

Butyl-2-cyanoacrylate is an easily applied, biocompatible, bioresorbable polymer glue that provides an alternative to conventional rigid fixation techniques. Our aim was to determine if cyanoacrylate fixation of the bone flap in a rabbit craniotomy model provides the healing and strength afforded by plate and screw fixation. We also investigated the inflammatory responses of adjacent tissues including the scalp, cranium, and brain. A unilateral parietal bone flap was elevated in 33 adult New Zealand rabbits. The bone was fixed in position with cyanoacrylate (n = 13), fixed with a microplate and screws (n = 14), or was replaced without fixation (sham-control, n = 6). Normal scar formation and no residual polymer were found in scalp specimens. Neuropathologic analysis identified the presence of residual polymer on the surface of 2 of the 13 rabbit brains. Histopathologic analysis of the bone flap-to-skull interface revealed no difference in the degree but rather in the quality of inflammation and healing between the plate and screw and polymer fixation groups. Microdensitometric analysis of the bone gap revealed nearly equivalent bone density in the cyanoacrylate and plated groups, tending to less density in the sham group (p = 0.11 and 0.09, respectively). An additional study focusing on neurotoxicity was performed in 20 adult rabbits with 3-week and 11-week recovery periods and similarly found the absence of a marked inflammatory response to the polymer. In conclusion, bone healing and soft-tissue inflammation were comparable between cyanoacrylate and plate and screw fixation groups. Although butyl-2-cyanoacrylate glue fixation may provide a reasonable alternative to hardware fixation, further investigations are necessary to identify its ideal utilization.

Animals↗
PubMed1998

Butyl-2-cyanoacrylate fixation of mandibular osteotomies.

Butyl-2-cyanoacrylate is an easily applied, bioresorbable, noninfective glue that may provide an alternative to conventional craniofacial fixation techniques. Recent studies have demonstrated that the healing and strength of glue fixation of bone fragments in the craniofacial skeleton is equivalent to that of plate and screw fixation. We sought to determine if this glue could also provide strength and healing in a more stressed environment, that of the mandible. Fourteen New Zealand White rabbits underwent mandibular osteotomies at the angle. The osteotomy was fixed with either a microplate (n = 4) or glue (n = 10). Mandibles were assessed 10 weeks postoperatively and classified according to bone healing, condylar morphology, and dental morphology. Callus and nonunion were more prevalent in the glued group, whereas condylar resorption was similar in both experimental groups. Despite the poor bony healing in the glued group, the teeth did not decay but modified their standard form to meet the demands of the anatomic deformity. Butyl-2-cyanoacrylate does not offer the biomechanical stability afforded by plates and screws in bone subject to large forces.

Animals↗
PubMed1996

Nonlethal case of otocephaly and its implications for treatment.

Otocephaly is a craniofacial syndrome with a constellation of findings consistent with symmetrically deficient development of the first branchial arch. Characteristically, those affected have ventrally displaced ears, microstomia, and an atrophic to absent mandible. Secondary to oropharyngeal incompetence, ventilatory, difficulties typically lead to the imminent death of these infants shortly after birth. Here we present a patient who survived well beyond the perinatal period with the support of pediatric intensivists and advanced technology available for the diagnosis and treatment of such a complex crajniofacial syndrome.

Craniofacial Abnormalities↗
PubMed1996

Giant congenital nevocellular nevus overlying an encephalocele.

Discussion regarding the diagnosis, prognosis, and management of giant congenital nevocellular nevi (GCNN) has permeated the literature because of concerns regarding malignant potential. As a derivative of dysgenetic neural crest development, GCNN histology in the neonate may be quite variable and not easily discernible from malignant melanoma, presenting a diagnostic dilemma to both the seasoned pathologist and surgeon. Here we present an interesting case of GCNN arising from a large encephalocele in a neonate. In spite of a clinically aggressive course, histology repeatedly failed to meet the criteria for melanoma until the diagnosis of malignant melanoma was made at autopsy. Clinical suspicion for malignancy must be high when evaluating atypical large nevi, and prompt surgical management is necessary to protect against the risk for malignant melanoma.

Brain Neoplasms↗
PubMed1995

Effect of yogurt on symptoms and kinetics of hydrogen production in lactose-malabsorbing children.

Lactase-deficient adults demonstrate improved lactose absorption and fewer symptoms when consuming yogurt than when consuming milk containing equivalent amounts of lactose. To examine this effect and its mechanisms in children, we compared symptoms and hydrogen production as an index of lactose malabsorption after typical servings of milk, pasteurized yogurt, and yogurt containing active live culture in 14 lactose-malabsorbing children (mean age 9.5 y). Symptoms and interval breath-hydrogen concentrations were recorded for 8 h after ingestion of 12 g lactose served as milk and yogurts. Lactose-malabsorbing children experienced significantly fewer symptoms after consuming yogurt containing active cultures than after consuming milk (P < 0.005). Pasteurized yogurt showed an intermediate effect. Lactose from yogurt was not better absorbed than was lactose from milk, as indicated by similar areas under the hydrogen curve; however, yogurt was associated with a delayed time to rise and lower rate of rise of the hydrogen curve. The rate of hydrogen rise correlated with the degree of symptoms. In children, mechanisms other than enhanced lactose absorption from yogurt may lead to changes in the kinetics of hydrogen production, which in turn are associated with improved tolerance.

Adolescent↗
PubMed1993

Nitric oxide inhibits resting sphincter of Oddi activity.

The sphincter of Oddi has basal myogenic phasic activity that is modulated by neural and hormonal pathways. Stimulatory innervation to this organ is cholinergic, whereas the inhibitory pathways are unknown. Nitric oxide (NO), generated from L-arginine, relaxes gastrointestinal smooth muscle in vitro. We, therefore, hypothesized that resting sphincter of Oddi and duodenal motilities are regulated by a NO-mediated inhibitory pathway. In 23 anesthetized prairie dogs, systemic blood pressure and sphincter of Oddi and duodenal motilities were monitored during systemic infusion of N omega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase. L-NAME was infused alone and simultaneously with excess D- and L-arginine. L-NAME alone and L-NAME with D-arginine produced hypertension and increased sphincter of Oddi and duodenal motilities. L-arginine blocked these increases, suggesting that baseline sphincter of Oddi and duodenal motility regulation involves the generation of NO from L-arginine. We conclude that baseline sphincter of Oddi phasic activity is regulated by cholinergic stimulatory and NO-mediated inhibitory neural pathways.

Amino Acid Oxidoreductases↗