Acute spinal cord degeneration following general anaesthesia in a young pony.
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Acute Disease↗
Biomedical subjects
K H Lam
Publications and source records attributed to K H Lam.
Maxillary swing approach for resection of tumors in and around the nasopharynx.
The efficacy of the anterolateral approach to the nasopharynx and its vicinity was evaluated. Using this maxillary swing approach, we have removed tumors in and around the nasopharyngeal region in 26 patients. Among them, 18 suffered from recurrent primary nasopharyngeal carcinoma after external radiotherapy, three patients had chordoma, two had schwannoma, one had adenocarcinoma of the nasopharynx, and one had malignant fibrous histiocytoma. The last patient had a recurrent deep-lobe parotid gland tumor localized in the paranasopharyngeal space. The facial wounds in all 26 patients healed primarily with no evidence of necrosis of the maxilla. Seven patients developed palatal fistula, five of them subsequently healed, whereas one patient required surgical closure and one had to wear a dental plate. This group of patients was followed up from 4 to 42 months (median, 15 months). Among the 18 patients with recurrent nasopharyngeal carcinoma, five had local recurrence, four died of other conditions, and nine of them are still alive with no evidence of disease. This gives an actuarial control of tumor in the nasopharynx of 42% at 3.5 years. In the eight patients remaining, one died of recurrent chordoma, two are alive with recurrent disease, and five are free of disease. Exposure of the nasopharynx and the paranasopharyngeal space is possible using the anterolateral approach. The associated morbidity is low.
Adenocarcinoma↗
Reinforced poly(L-lactic acid) fibres as suture material.
In this study, reinforced poly(L-lactic acid) (PLLA) fibers made by a dry-spinning/hot-drawing process were evaluated for use as a suture. The initial tensile strength of the PLLA fibers was lower than the initial tensile strength of the commercially available sutures: PDS, Vicryl, silk, and Ethilon. However, after 12 weeks immersion in a phosphate saline buffer at 37 degrees C, PDS sutures have lower tensile strength than PLLA sutures and the tensile strength of Vicryl was unmeasurable because of fragmentation. Initially, PLLA fibers disintegrated into fibrils during degradation triggering an inflammatory response comparable to degradable multifilament sutures. However, the intensity of the inflammatory response against the PLLA fibers decreased and after 80 weeks implantation in the muscle layer of the abdominal wall of rats it was comparable to the one against Ethilon. The inflammatory response against Ethilon, which is considered to be nondegradable, increased in the same period, probably due to the change in shape. In practice, the handling characteristics of PLLA sutures are superior to the monofilament sutures like PDS and Ethilon and comparable with the multifilament sutures like Vicryl and silk. The knot security of PLLA sutures are expected to be better than the knot security of the monofilament sutures, but this remains to be investigated. It is concluded that dry-spun/hot-drawn (reinforced) PLLA fibers have the potential for use as long-term degradable suture material.
Animals↗
The influence of surface morphology and wettability on the inflammatory response against poly(L-lactic acid): a semi-quantitative study with monoclonal antibodies.
In this study, the influence of surface morphology and wettability of both degradable and nondegradable polymer films on the inflammatory response after subcutaneous implantation in the rat was investigated. Degradable non-porous, porous, and "combi" (porous with a nonporous layer on one side) poly(L-lactic acid) (PLLA) films and nondegradable polytetrafluoroethylene (PTFE) and (porous) expanded PTFE (e-PTFE) were used. Contact angles measurements indicate that PLLA is more hydrophillic than PTFE. Assessment of the inflammatory response was performed after various periods of implantation (up till 180 days), with both conventional light microscopy and immunohistochemistry using monoclonal antibodies (mAbs). The inflammatory response observed initially can largely be considered as part of the wound healing reaction, and up till day 40 the inflammatory response against PLLA was minimally more intense than against PTFE (porous as well as nonporous). From day 40 on, the PLLA films provoke a more intense inflammatory response as compared to the PTFE films. Both porous PLLA and the porous side of the "combi" PLLA film provoke a more intense inflammatory response than nonporous PLLA and the nonporous side of the "combi" PLLA film, respectively. In general, PTFE and e-PTFE films provoke an inflammatory response which is minimally more intense than the one provoked by the sham operation. Almost no ingrowth of tissue was observed in the porous e-PTFE films. In contrast, there was abundant tissue ingrowth in and an inflammatory response against porous PLLA. It can be concluded that biodegradable PLLA films provoke a more intense inflammatory response than nondegradable PTFE films. Also, porosity enhances the inflammatory response. However, porosity enhances the inflammatory response only when the wettability of a biomaterial permits cellular ingrowth.
Animals↗
Stand-alone stenting of the left main coronary artery and 16-month patency despite sepsis and complicated hospital course.
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Angioplasty, Balloon, Coronary↗
Infants tolerate spinal anesthesia with minimal overall autonomic changes: analysis of heart rate variability in former premature infants undergoing hernia repair.
Unlike adults, neonates tolerate high thoracic spinal anesthesia with minimal changes in heart rate (HR) and arterial blood pressure. To examine the potential autonomic regulatory mechanisms which may account for these findings, the relation between short-term heart rate variability (HRV) and respiratory activity was analyzed in a group of eight ASA grade II former premature infants undergoing high thoracic spinal anesthesia for inguinal hernia repairs. Quantitative measures of sympathetic (As) and parasympathetic (Ap) modulation of HR were derived. HR, arterial blood pressure, and a calibrated respiratory signal were recorded during 4.4-min stable epochs in eight subjects 1) preoperatively, 2) postincision after high thoracic spinal anesthesia, and 3) during an active sleep state in the postoperative period. Power spectral analysis of HRV and respiratory power yielded measures of low-frequency power (LFP: 0.02-0.15 Hz) and high-frequency power (HFP: 0.15-0.8 Hz). Transfer function analysis between respiratory activity and HR were used to quantify As and Ap. All subjects had successful high thoracic spinal anesthesia with highest levels ranging from C7-T4. Mean HR, blood pressure, and respiratory power did not change significantly with high thoracic spinal anesthesia. LFP and HFP both decreased significantly, whereas the LFP/HFP ratio remained stable. Group mean As and Ap both decreased, but the changes were not significant. Despite overall cardiovascular stability, HRV decreased with high thoracic spinal anesthesia, but the balance between LFP and HFP remained stable, suggesting that the reflex response to high thoracic spinal anesthesia was predominantly diminished parasympathetic modulation of cardiac function. The expected decrease in HR and blood pressure from the sympatholysis which results from high thoracic spinal anesthesia were apparently offset by withdrawal of cardiac vagal activity.
Anesthesia, Spinal↗
Thyroidectomy during laryngectomy for advanced laryngeal carcinoma--whole organ section study with long-term functional evaluation.
Whole organ step-serial section of laryngectomy specimens was carried out in 16 patients with a T3 and T4 laryngeal carcinoma to study the involvement of the thyroid gland. Three patients (19%) were found to have tumour invasion into the thyroid gland, and two patients (16%) were found to have tumour on the thyroid capsule. Of the 12 patients who had tumour involving the subglottic region, five patients were found to have involvement of the thyroid gland. Of the remaining four patients without subglottic tumour extension, none had tumour involvement of the thyroid gland. Of the five patients who had long-term survival of 10 years, two patients had subclinical hypothyroidism and one patient had clinical hypothyroidism. We recommend routine hemithyroidectomy when the subglottic region is involved by tumour. The whole thyroid gland should be preserved when the laryngeal tumour is confined to the supraglottic and glottic regions without clinical evidence of thyroid gland involvement.
Aged↗
Desmin transgene expression in mouse somites requires the presence of the neural tube.
Transgenic mice were used to study the effect of the neural tube on somite myogenesis. These mice express a transgene in which the 1 kb DNA 5' regulatory sequence of the desmin gene is linked to a reporter gene which codes for E. coli beta-galactosidase. In order to determine whether the developmental fate of cells, specifically the prospective myogenic population, in newly developed somites was pre-determined, newly formed somites were isolated from the caudal region of day 9.5 transgenic embryos and transplanted into 8.5 day non-transgenic host embryos. Even though the implanted somites were not oriented in the host embryos, all the specimens examined developed normally at the graft site forming a dermatome, myotome and sclerotome in the correct anatomical positions. The myotome even expressed the desmin transgene. In addition, we isolated the 3 most caudal somites, that is, the most recently developed somites, from day 9.5 transgenic embryos and maintained them on gelatin-coated coverslips in culture for up to 4 days. While these somite explants did not develop myoblasts, it was possible to induce myogenesis by introducing pieces of neural tube into the explant cultures. These results suggest that the developmental fate of cells within the newly formed somite is not predetermined, but is dependent on the microenvironment surrounding the developing somite.
Animals↗
Multifocal nature of adenolymphoma of the parotid.
The multifocal nature of adenolymphoma of the parotid salivary gland was studied in 24 patients who underwent parotidectomy. Twenty-six resected specimens were examined by a step-serial whole-organ sectioning technique; multiple adenolymphoma was found in 13. The maximum number of synchronous tumours in any gland was four. Salivary epithelial elements were found embedded within lymph nodes in nine resected specimens. Synchronous or metachronous bilateral tumours were found in eight patients. The multifocal nature of adenolymphoma of the parotid gland is demonstrated.
Adenolymphoma↗
Degradation and intrahepatic compatibility of albumin-heparin conjugate microspheres.
The in vitro degradation properties of glutaraldehyde cross-linked albumin and albumin-heparin conjugate microspheres (AMS and AHCMS respectively) were evaluated using light microscopy, turbidity measurements and heparin release determinations, showing that the microspheres are degraded by proteolytic enzymes such as trypsin, proteinase K and lysosomal enzymes. The degradation rate was inversely related to the cross-link density of the microspheres. After intrahepatic administration of AHCMS, cross-linked with 0.5% glutaraldehyde, to male Wag/Rij rats by injection into a mesenteric vein (intravenoportal: i.v.p.), the microspheres were entrapped in the hepatic vascular system. The AHCMS were entrapped within terminal portal veins predominantly at the periphery of the liver. The AHCMS were degraded by cellular enzymatic processes within 2 wk after injection, with a half life of approximately 1 d. Biocompatibility of AHCMS and adriamycin-loaded AHCMS was evaluated by histological assessment of the mitotic activity of liver parenchyma and inflammatory response, and by determination of liver damage marker enzymes during 4 wk after administration. Liver damage marker enzymes were not increased compared with controls, nor were adverse effects observed upon histological examination. There was no difference in response between empty and adriamycin-loaded AHCMS.
Albumins↗
Tracheostomal stenosis after total laryngectomy: an analysis of predisposing clinical factors.
Stenosis of the terminal tracheostome is a distressing complication of total laryngectomy. A retrospective analysis of 207 patients who underwent total laryngectomy is presented; an overall incidence of tracheostomal stenosis of 13% is reported. The incidence of tracheostomal stenosis is higher in females (26%), patients having immediate tracheoesophageal puncture (19%), pectoralis major myocutaneous flap pharyngeal reconstruction (26%), and tracheostomal infection (50%) which is shown to be significant (P < .05). However, on multivariate analysis, only female sex and tracheostomal infection are independent determinants. Recognition of these clinical factors identifies patients at increased risk of developing this complication and thus allows appropriate perioperative planning to minimize its incidence.
Causality↗
Regional chemotherapy for recurrent squamous head and neck cancers through a saphenous vein interposition graft.
Regional chemotherapy for head and neck cancers is effective, but the intra-arterial catheter is not without problems. We interposed a segment of saphenous vein within the carotid system to administer chemotherapeutic agents percutaneously via the arterialized venous segment. From 1983 to 1990, saphenous vein interposition graft was performed after radiotherapy in 24 patients with persistent or recurrent squamous head and neck cancers, which were also considered unresectable. There was no operative mortality. Two patients developed thrombosed vein graft; another two had wound infection; and one patient had a neck hematoma. Cisplatin was administered percutaneously every week via the saphenous vein graft. The response rate was 64% (complete response, 23%; partial response, 41%), and the 5-year actuarial survival rate was 31%. The 1-year survival rates for patients with complete, partial, and no response were 80%, 33%, and 13%, respectively. Saphenous vein interposition graft is a safe and convenient way of delivering intra-arterial chemotherapy, and it provides significant palliation for patients with recurrent nonresectable squamous head and neck cancers after radiotherapy.
Aged↗
The effect of phagocytosis of poly(L-lactic acid) fragments on cellular morphology and viability.
The aim of this study was to investigate the effect of phagocytosed poly(L-lactic acid) particles on the morphology and viability of phagocytes, mainly macrophages. Therefore, predegraded poly(L-lactic acid) (P-PLLA) and nontreated PLLA (N-PLLA) particles, both having diameters not exceeding 38 microns, were injected intraperitoneally in mice. P-PLLA particles were obtained by 25 kGy gamma-irradiation of N-PLLA particles. N-PLLA and P-PLLA particles were injected using an 0.3% ethanol/0.9% saline solution intraperitoneally to the mice. We also studied the release of the absorbed ethanol as a possible model for the release of low molecular weight, potentially toxic products. As control, nondegradable polytetrafluoroethylene (PTFE) particles and the carrier solution were used. After 1, 2, 3, 4, 5, and 7 days, the cells of the abdominal cavity were harvested to study the effect of phagocytosis of polymer particles on phagocytic cell morphology and viability. Studies with transmission electron microscopy indicated that, upon injection of particles in the peritoneal cavity, macrophages demonstrated signs of cell damage, cell death, and cell lysis due to phagocytosis of a large amount of P-PLLA particles. The morphology of the cells that had phagocytosed the N-PLLA and PTFE particles did not differ substantially from those of control animals in which only the solution was injected. Also, in the controls, hardly any cell death and no debris was observed. When the PLLA particles were injected as a suspension in a 0.3% ethanol/0.9% saline solution, no difference was observed between N-PLLA and P-PLLA. After phagocytosis, both cause cell damage, sometimes leading to cell death.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Pneumogastrogram in the diagnosis of perforated peptic ulcer.
Early diagnosis and surgical intervention is important in the management of peptic ulcer perforation. This study looks at the value of a pneumogastrogram in the diagnosis of patients suspected of having a perforated peptic ulcer. One hundred and twenty-nine patients were studied. Pneumogastrogram increased the diagnostic yield of pneumoperitoneum from 66% following plain erect X-ray examination to 91%. The procedure was free of complications.
Adolescent↗
Obturator hernia: a continuing diagnostic challenge.
BACKGROUND: The rare obturator hernia has a high incidence of potentially lethal complications. This report reviews this condition and stresses the dangers of unrecognized obturator hernia. METHODS: Thirteen patients with 14 obturator hernias were seen during a 5-year period. All the patients were emaciated and elderly, and 12 were women. They all had clinical features of small bowel obstruction. The classic Howship-Romberg sign was present in only three patients. The diagnosis was made before surgery in five patients. RESULTS: All hernial sacs contained small bowel. Ileum were present in 11 instances. Richter-type hernia was present in 10 cases. Bowel resection for gangrenous loop was required in seven instances. Apart from associated poor medical conditions, delay in presentation and operation also contributed to the high morbidity and mortality rates. Five patients (38.5%) had postoperative complications, and two patients (15.4%) died of chest infections. CONCLUSIONS: The need for awareness of the condition is stressed and the diagnosis of obturator hernia should be strongly suspected in a thin, elderly woman who has small bowel obstruction and no previous abdominal surgery.
Aged↗
Pathological basis of surgery in the management of postradiotherapy cervical metastasis in nasopharyngeal carcinoma.
Radical neck dissection was performed on 43 patients with nasopharyngeal carcinoma in whom persistent or recurrent cervical metastasis developed after radiotherapy. The pathologic nature of the tumor in the cervical lymph nodes was studied with step serial sectioning of the entire radical neck dissection specimen at 3-mm intervals. In 70% of patients, more tumor-harboring lymph nodes were detected in the specimen when compared with clinical examination. The extensive behavior of the tumor in the cervical metastases was reflected by the presence of extracapsular spread in 70% of the lymph nodes and the existence of isolated clusters of tumor cells in 35% of the specimens studied. Tumor tissue lying in close proximity to the spinal accessory nerve was demonstrated in 27.5% of the specimens, and 72% of the tumor-bearing lymph nodes were located in the posterior triangle. Radical neck dissection is recommended as the salvage procedure for these patients.
Adult↗
Treatment of neck nodes in oral cancer.
In a review of 98 patients who were operated upon for squamous oral cancer, a high proportion of them (48%) developed recurrence after a minimum follow-up of 2 years. Nodal status significantly affected the nodal recurrence rate and survival. For N0, N1, N3 tumours, the 2-year nodal recurrence-free rates were 79, 83, 18%, and the 2-year survival rates were 58, 59 and 10%. For small tumours with N0 neck, the group with elective neck dissection and the observed group did not have statistically different nodal recurrence-free rate and overall survival. The 2-year nodal recurrence-free rate was 92% versus 77% (P value > 0.3) and the 2-year survival rate was 56% versus 72% (P value > 0.6). In patients with N1 neck, radical neck dissection was reasonably effective in controlling neck metastasis. Radical neck dissection in an attempt to treat fixed neck nodes (N3) was not successful in controlling the neck disease.
Adult↗
Magnetic resonance imaging using a clinical whole body system: an introduction to a useful technique in small animal experiments.
A clinical whole body magnetic resonance imaging (MRI) system with high resolution coils was used to obtain non-invasive images of the living rat. The results demonstrate the feasibility of the set-up and the advantages of this new imaging technique: detailed information, no extra costs, longitudinal studies without killing animals and simple anaesthesia. It is concluded that in small animal experimentation, this use of high resolution coils in whole body magnetic resonance systems may be particularly helpful in establishing effects of experimental procedures. Whenever non-invasive visualization is required, especially in longitudinal animal studies, e.g. biomaterial research or tumour investigation, this use of MRI will offer challenging possibilities.
Animals↗