Biomedical subjects
Publications and source records attributed to J L Leach.
The vertebral artery normally arises from the subclavian artery, and variations in its origin have been described. We describe a unique case of the left vertebral artery arising from the thyrocervical trunk.
Surgeons involved in microtia repair recognize the difficulty in creating a natural appearing ear. One key to successful reconstruction is to provide sufficient relief between the helix, scaphoid fossa and antihelix to create the illusion of thin skin overlying thin cartilage. Problems such as thick skin, hair-bearing skin and poor-quality cartilage serve to frustrate the surgeons attempt to achieve the desired result. Surgical techniques to improve cartilaginous framework definition in microtia repair are discussed.
OBJECTIVE: To prove the efficacy of bone morphogenic protein as an osteoinductive agent in irradiated tissue. DESIGN: Prospective randomized controlled trial designed to test the effectiveness of recombinant bone morphogenic protein 2 (rBMP-2) combined with solid hydroxyapatite disks in an irradiated tissue bed. SUBJECTS: Eighteen adult, male, white New Zealand rabbits weighing 3.0 to 3.5 kg. INTERVENTION: The rabbits were randomly divided, with 9 receiving radiation treatment and 9 receiving no radiation treatment. Each animal underwent implantation of 2 hydroxyapatite disks onto the snout at 9 weeks following radiation treatment. One disk was impregnated with rBMP-2 and the other with buffer only. The animals were killed at 3, 6, or 20 weeks after implantation for analysis. RESULTS: Histological analysis demonstrated that rBMP-2 was equally effective as an osteoinductive agent in the irradiated and nonirradiated tissue. We also found significantly increased new bone formation in the rBMP-2 group vs the buffer group. CONCLUSIONS: This study supports the potential clinical utility of rBMP-2 and solid hydroxyapatite in irradiated tissue beds. These findings have interesting implications for patients with head and neck cancer who have undergone radiation therapy and need bony reconstruction.
The lateral thigh free flap is a fasciocutaneous flap based on the cutaneous perforators of the deep femoral vessels. Although originally described in 1983, it has had very few reports in the literature. This article describes the flap and reports our findings and outcomes in nine cadavers (18 thighs) and 33 clinical cases. The position of the vascular pedicle may vary in each case but has always been found to be present. Successful transfer occurred in 30 of 33 cases. Flap loss was attributable to infection, fistula, and hematoma in three of four cases. The flap was especially useful in large defects, most commonly total and base-of-tongue defects. We have found this flap to be reliable and to result in minimal morbidity.
As more surgical procedures are being performed under local anesthesia and intravenous sedation, complications associated with these techniques are more likely to be experienced. We report a case of an intraoperative flash fire that occurred while supplemental oxygen was being used in this scenario. A literature review and suggestions for prevention of this complication are discussed.
The IgG transporter responsible for ferrying maternal IgG across the human placenta to fetal circulation has not been identified, although the human homologue of the neonatal rat Fc receptor (FcRn), a heterodimer with pH-dependent IgG affinity, structurally similar to MHC Class I molecules, was recently proposed as a candidate. Affirming this hypothesis, we describe herein the specific copurification from human placenta of 46- and 14-kDa proteins by IgG affinity at acid pH. The larger protein, characterized by its amino acid sequence and by immunoblot, is the alpha-chain of human FcRn (hFcRn). The smaller is beta2-microglobulin. Their coisolation by ligand affinity suggests that they comprise the hFcRn heterodimer. Placenta sections stained immunohistochemically with anti-hFcRn alpha-chain peptide Abs show extensive expression of hFcRn in the syncytiotrophoblast and traces in the endothelium and other unidentified cells of the villus stroma. We find alpha-chain mRNA by Northern analysis in human placenta and in human trophoblast-like cell lines (JEG-3, ED27) but not in a human myelocytic cell line (HL60). We suggest that the placental hFcRn heterodimer may transport IgG to the fetus by a mechanism in which maternal IgG is pinocytosed nonspecifically and then carried to fetal tissues by a pH gradient from acidic endosomes to the pH-neutral basolateral surface of the syncytiotrophoblast. Furthermore, the known characteristics of FcRn suggest a wider function, that it is the receptor postulated by Brambell in the 1960s to regulate tissue and serum IgG concentrations by controlling IgG transport and catabolism.
PURPOSE: To determine the imaging appearance and frequency with which arachnoid granulations are seen on contrast-enhanced CT and MR studies of the brain. METHODS: We retrospectively reviewed 573 contrast-enhanced CT scans and 100 contrast-enhanced MR studies of the brain for the presence of discrete filling defects within the venous sinuses. An anatomic study of the dural sinuses of 29 cadavers was performed, and the location, appearance, and histologic findings of focal protrusions into the dural sinus lumen (arachnoid granulations) were assessed and compared with the imaging findings. RESULTS: Discrete filling defects within the dural sinuses were found on 138 (24%) of the contrast-enhanced CT examinations. A total of 168 defects were found, the majority (92%) within the transverse sinuses. One third were isodense and two thirds were hypodense relative to brain parenchyma. Patients with filling defects were older than patients without filling defects (mean age, 46 years versus 40 years). Discrete intrasinus signal foci were noted on 13 (13%) of the contrast-enhanced MR studies. The foci followed the same distribution as the filling defects seen on CT scans and were isointense to hypointense on T1-weighted images, variable in signal on balanced images, and hyperintense on T2-weighted images. Transverse sinus arachnoid granulations were noted adjacent to venous entrance sites in 62% and 85% of the CT and MR examinations, respectively. Arachnoid granulations were found in 19 (66%) of the cadaveric specimens, in a similar distribution as that seen on the imaging studies. CONCLUSION: Discrete filling defects, consistent with arachnoid granulations, may be seen in the dural sinuses on 24% of contrast-enhanced CT scans and on 13% of MR studies. They are focal, well-defined, and typically located within the lateral transverse sinuses adjacent to venous entrance sites. They should not be mistaken for sinus thrombosis or intrasinus tumor, but recognized as normal structures.
Human milk-borne ribonucleotides reportedly have important physiological roles in breast-fed infants. Previous studies measured the free nucleotide content of human milk. To more fully evaluate the physiological capacity of nucleotides in human milk, we determined the monomeric and polymeric ribonucleotide and ribonucleoside content of milk pooled from 11 American women. Subsequently, we determined the total potentially available nucleosides (TPAN) of pooled and individual milk samples segregated by stage of lactation from 100 women in three European countries to test for effect of culture and diet. The methodology simulated in vivo digestion. Polymeric ribonucleotide (primarily RNA), monomeric ribonucleotide, and ribonucleoside-containing adducts (eg, uridine diphosphate hexose) were enzymatically hydrolyzed to their constituent ribonucleosides, the preferred form for absorption. Free and enzymatically liberated nucleosides were then measured by HPLC to yield the TPAN value. The mean (+/- SD) TPAN concentration of the 16 pooled European samples, derived from the 100 individual samples, was 189 +/- 70 mumol nucleoside/L human milk (range 82-402 mumol/L). The means (mumol/L human milk) of each nucleoside were 38 for uridine, 88 for cytidine, 31 for guanosine, and 32 for adenosine. These values included the contribution from the cellular portion of human milk. Only one of the 16 pooled samples contained a measurable amount of inosine (4 mumol/L). The potentially available ribonucleosides in the human milk samples were predominantly present as monomeric (36 +/- 10%) and polymeric (48 +/- 8%) nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)
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Plain radiography remains the standard imaging modality for initial evaluation of cervical spine trauma. CT and MR imaging play an important role in additional evaluation for patients with known or suspected injuries. The role of conventional tomography and myelography is limited.
The current accepted treatment for chronic frontal sinus disease unresponsive to medical management and endoscopic surgery is an external approach to either obliterate the sinus or restore communication to the nasal cavity. Here reported is an endoscopic approach for resection of the intranasal frontal sinus floor, a modification of a procedure first described by Lothrop in 1899. Eleven patients underwent this operation from April 1993 to December 1993. One complication, a cerebrospinal fluid leak treated successfully endoscopically, has occurred. Of the 7 patients followed up 3 months or longer after surgery, only 1 has developed symptoms of recurrent frontal sinusitis. On the basis of this limited preliminary experience, the endoscopic Lothrop procedure shows promise as an effective operation designed to establish a physiologic communication between the frontal sinus and the nasal cavity in selected patients who would otherwise be candidates for an external approach.
Reliable reconstructive techniques are essential in the surgical treatment of head and neck cancer patients. Free flaps have often been used as reconstructive options of last resort in the head and neck because of the need for added technical skill, a longer operating time, and a perception of poor reliability. This study reviews our experience with 39 free flaps performed by the Otolaryngology-Head and Neck Surgery Service. For the first 17 cases, an interrupted anastomotic technique was used; a running technique was performed in the remaining 22 cases. The average total ischemic time (3.7 vs. 2.7 hours; p < 0.001) was significantly less with a running technique. There were 10 complications: 7 minor would problems, 1 death from aspiration without surgical wound/flap problem, and 2 cases requiring second flaps (1 flap necrosis, 1 fistula with healthy free flap). No statistical correlation was found between complications and ischemic time, suture technique, age, or hospital (five hospitals). Free flaps are reliable and may obviate the need for sacrifice of trunk muscles for wound closure (e.g., fascicocutaneous free flaps instead of myocutaneous flaps); therefore we recommend revascularized free flaps as the primary mode of reconstruction for head and neck defects.
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Fosfomycin is an antibiotic that has been found to reduce the ototoxicity of aminoglycoside antibiotics and cisplatin when systemically coadministered. Polymyxin B, an antibiotic frequently used in ototopical preparations, has been shown to be ototoxic in experimental studies. To investigate the effect of fosfomycin on polymyxin B ototoxicity, topical administration of the two agents into the middle ear cavity was performed. Two groups of chinchillas were used. One group received applications of polymyxin B alone, and the second group received polymyxin B combined with fosfomycin. It was found that application of polymyxin B produces severe damage to the cochlea. However, when polymyxin B was given in combination with fosfomycin, cochlear damage was dramatically reduced. It is likely that in clinical use, a combination of polymyxin B and fosfomycin would demonstrate reduced risk of ototoxicity.
Complex partial seizures are associated with alterations in regional cerebral blood flow in abnormally spiking foci, as shown by positron emission tomography and single photon emission computed tomography, with an increase in flow ictally and a decrease interictally. Alterations of vasoregulation during ictal periods have also been described in animal seizure models. An electron microscopic study on human brain tissue from seven patients undergoing resections for the treatment of intractable complex partial seizures was performed to examine ultrastructural changes of the microvasculature and their locations within the microvessel wall. Biopsies were obtained intraoperatively from temporal lobe regions with electrocorticographically detected abnormal spiking and from regions without abnormality on electrocorticograms (control samples) removed as part of the therapeutic resection. A total of 539 microvessels from three regions were evaluated: spiking mesial temporal lobe, spiking lateral temporal cortex, and nonspiking (control) cortex. Evidence of pericyte degeneration (aggregates of cellular debris within the basement membrane) was noted in the majority of spiking area microvessels (76.7% in spiking mesial temporal cortex; 69.8% in spiking lateral temporal cortex) as compared with 37.8% of control microvessels (P less than 0.0005). Morphometric studies revealed a significant increase in total wall thickness, pericyte-basement membrane unit thickness, pericyte cytoplasmic density, basement membrane density, and basement membrane thickness in microvessels from spiking (mesial and lateral temporal cortex), as compared to control areas (P less than 0.01). No statistically significant difference was noted in pericyte coverage or pericyte or endothelial mitochondrial densities between microvessels in spiking and control regions. This study shows degeneration of pericytes, cells thought to play an essential role in microvascular hemodynamics, and thickening of microvessel walls in abnormally spiking brain regions in patients with intractable complex partial seizures. The pericyte degeneration and basement membrane thickening in abnormally spiking areas may explain alterations in vasoregulation, by a decrease in the microvascular compliance and in cross-capillary diffusion.
OBJECTIVE: To evaluate the clinical outcomes with the use of a dual-porosity expanded polytetrafluoroethylene implant for midfacial rejuvenation. DESIGN: An institutional review board-approved retrospective chart review was conducted of all patients who underwent implantation with the dual-porosity expanded polytetrafluoroethylene implant between 2001 and 2005. RESULTS: A total of 170 patients, with 612 implants, were evaluated. Only 8 patients had minor complications, 3 of which necessitated implant removal. The overall results of independent observer analysis of outcomes were favorable in the majority of cases. CONCLUSION: The dual-porosity expanded polytetrafluoroethylene implant is safe and reliable to use for midfacial implantation.