Biomedical subjects

M B Wang

Publications and source records attributed to M B Wang.

At least 37 records · Page 2Linked to original sources

PubMed1999

Open bedside tracheotomy in the intensive care unit.

OBJECTIVE: To demonstrate that open bedside tracheotomy is an efficient, safe, and cost-effective procedure. STUDY DESIGN: Retrospective review of more than 200 open bedside tracheotomies performed at UCLA Medical Center, Harbor-UCLA Medical Center, and West Los Angeles VA Medical Center from 1995 to 1998. METHODS: The only personnel required for the procedure were an attending or senior resident and a junior resident or intern, as well as the respiratory therapist to withdraw the endotracheal tube. No anesthetist or scrub nurse was present for any of the procedures. The procedure took an average of 15 to 25 minutes. Patients were followed for 30 days after surgery to determine the incidence of complications. RESULTS: The incidence of major complications related to the procedure, including hemorrhage and myocardial infarction, was less than 1%. The incidence of minor complications, including moderate bleeding at the tracheotomy site, was 4%. Overall mortality within 30 days was 8%, but was not related to the tracheotomy for any patients in this series. The charge for the procedure was $233 for the tracheotomy tube supplies and instruments. This cost compares favorably with an average charge of more than $3000 for the procedure in the operating room and about $1000 for a percutaneous tracheotomy kit. CONCLUSION: Review of our experience demonstrates that open bedside tracheotomies can be performed more efficiently and economically than operating room tracheotomies. The safety of this procedure is comparable to percutaneous tracheotomy but at a decreased cost.

Adolescent↗

PubMed1999

Radiotherapy followed by neck dissection for small head and neck cancers with advanced cervical metastases.

Patients with small or occult primary carcinomas of the head and neck with advanced cervical metastases present a difficult problem for the otolaryngologist. A retrospective review was performed of patients who presented to UCLA Medical Center between January 1986 and June 1996 with small or occult primary tumors of the head and neck with advanced cervical metastases. The treatment algorithm consisted of initial radiotherapy to the primary site and the neck, followed in 6 to 8 weeks with endoscopy and biopsy of the primary tumor site. As long as the repeat biopsy of the primary tumor site was negative by frozen section, an immediate neck dissection was performed, even if no residual neck disease was present. Almost 40% of patients with no clinical evidence of neck disease following radiotherapy had evidence of metastatic cancer on histopathologic examination. While some would consider a watchful waiting policy when there is no clinically detectable neck disease following radiotherapy, we believe it is preferable to perform immediate surgery in such patients, in light of the high incidence of microscopic metastatic disease.

Carcinoma, Squamous Cell↗

PubMed1999

Distant lymphatic metastasis from head and neck cancer.

A predictable pattern of metastasis based on tumor histology and site of origin has been well documented for most cancers that arise in the head and neck region. The current study demonstrates that this predictable pattern of metastasis can be significantly impacted by previous therapy, resulting in unusual patterns of metastasis in patients with recurrent tumors. A retrospective case series of 5 patients with head and neck carcinomas who developed metastases to distant lymph nodes is presented. All patients underwent surgery and radiotherapy to the primary tumor and regional lymphatics at the time of their initial treatment. All of the patients developed a local recurrence less than a year before the detection of distant lymphatic metastases. Cytology or excision confirmed metastases to the axillary, inguinal, or anterior intercostal lymph nodes. All of the patients underwent aggressive surgery for attempted cure of the local recurrence shortly before the presence of distant lymphatic metastases was clinically recognized. The metastatic workup of patients with carcinomas of the head and neck frequently includes examination of the regional lymph nodes as well as chest radiography, liver function tests, and serum calcium determination. This evaluation may fail to detect metastases to distant lymph nodes in patients who present with recurrent or second primary cancers. Such patients should undergo careful examination of all major lymph node-bearing regions of the body when being evaluated for the presence of distant metastases.

Aged↗

PubMed1998

Virus resistance and gene silencing in plants can be induced by simultaneous expression of sense and antisense RNA.

Many examples of extreme virus resistance and posttranscriptional gene silencing of endogenous or reporter genes have been described in transgenic plants containing sense or antisense transgenes. In these cases of either cosuppression or antisense suppression, there appears to be induction of a surveillance system within the plant that specifically degrades both the transgene and target RNAs. We show that transforming plants with virus or reporter gene constructs that produce RNAs capable of duplex formation confer virus immunity or gene silencing on the plants. This was accomplished by using transcripts from one sense gene and one antisense gene colocated in the plant genome, a single transcript that has self-complementarity, or sense and antisense transcripts from genes brought together by crossing. A model is presented that is consistent with our data and those of other workers, describing the processes of induction and execution of posttranscriptional gene silencing.

Journal Article↗

PubMed1998

Spontaneous cervical hemorrhage with near-complete airway obstruction.

BACKGROUND: Retropharyngeal hematoma is a rare entity which may progress rapidly to airway obstruction. Previously documented causes have included coagulopathic states, trauma, infection, parathyroid adenoma rupture, and foreign-object ingestion. Four cases of spontaneous retropharyngeal hematomas without any known predisposing risk factors have been previously reported. Two of these cases had fatal outcomes. METHODS: A case report is presented and the literature reviewed. RESULTS: Spontaneous cervical hematoma with parapharyngeal and retropharyngeal involvement which caused near-complete respiratory obstruction occurred in an otherwise healthy young man following straining. Initial management involved fiberoptic nasotracheal intubation. Subsequent right neck exploration revealed hemorrhage from a branch of the external carotid artery, which was ligated. An arteriogram revealed minimal flow through the right external carotid artery and its branches. The patient was extubated and discharged uneventfully on the fourth postoperative day. CONCLUSION: The possible etiology for this case is discussed, and a review of the literature and the role of surgery in the management of this entity is outlined.

Adult↗

PubMed1998

Deletion of P15 (MTS2) in head and neck squamous cell carcinomas.

INTRODUCTION: The purpose of this study was to determine whether the multiple tumor suppressor 2 (MTS2) gene, encoding an inhibitor (p15) of cyclin D-dependent kinases 4 and 6 (cdk4, cdk6), is deleted in head and neck squamous cell carcinomas (HNSCC). There is a high frequency of LOH for the 9p21-p22 region in HNSCCs, as well as in gliomas, leukemias, and cell lines from multiple tumor types; thus, this region is suspected to contain a tumor suppressor gene or genes. P16 (MTS1), an inhibitor of cdk4 and cdk6, resides within the deleted 9p21 region in these tumors. A neighboring gene, p15 (MTS2), has biochemical properties similar to those of p16, but has not been characterized in HNSCC. METHODS: Twenty-one head and neck squamous cell carcinomas and their proximal margins were snap frozen at the time of surgical resection. DNA isolation was performed using standard phenol and chloroform extraction. Standard PCR methods were used with primers P15-1F and P15-1R, specific for exon 1 of the p15 gene, as described previously. All samples were amplified for beta-Globin as a positive control. PCR products were stained with ethidium bromide and run on 6% polyacrylamide gels. Expected sizes for the PCR products were p15, 532 bp, and beta-globin, 238 bp. Results. Of 21 proximal margins, all demonstrated normal amplification of p15 DNA, all having a visible 532bp PCR product. Of 21 HNSCC tumors, 9 showed no amplification of the p15 gene; none of these 9 neoplasms had visible PCR products. All proximal margins and head and neck squamous cell carcinomas demonstrated amplification of the beta-globin gene, indicating that the DNA used was of good quality. CONCLUSIONS: Although PCR is not a quantitative technique, densitometric analysis of PCR products showed it was unlikely that the p15 gene was present in more than a small fraction of the tumor cells. The amount of the p15 PCR product in these cells was less than 3% of that observed in reactions containing an equal amount of DNA from normal cells. We are the first to show an absence of normal p15 exon 1 gene amplification in nearly 50% of HNSCCs studied. Loss of the MTS2 gene product, p15, may contribute to the loss of cell cycle and growth regulation seen in HNSCC.

Carcinoma, Squamous Cell↗

PubMed1998

Comparison of the coat protein, movement protein and RNA polymerase gene sequences of Australian, Chinese, and American isolates of barely yellow dwarf virus transmitted by Rhopalosiphum padi.

Barely yellow dwarf luteovirus-GPV (BYDV-GPV) is a common problem in Chinese wheat crops but is unrecorded elsewhere. A defining characteristic of GPV is its capacity to be transmitted efficiently by both Schizaphis graminum and Rhopaloshiphum padi. This dual aphid species transmission contrasts with those of BYDV-RPV and BYDV-SGV, globally distributed viruses, which are efficiently transmitted only by Rhopaloshiphum padi and Schizaphis graminum respectively. The viral RNA sequences encoding the coat protein (22K) gene, the movement protein (17K) gene, the region surrounding the conserved GDD motif of the polymerase gene and the intergenic sequences between these genes were determined for GPV and an Australian isolate of BYDV-RPV (RPVa). In all three genes, the sequences of GPV and RPVa were more similar to those of an American isolate of BYDV-RPV (RPVu) than to any other luteovirus for which there is data available. RPVa and RPVu were very similar, especially their coat proteins which had 97% identity at the amino acid level. The coat protein of GPV had 76% and 78% amino acid identity with RPVa and RPVu respectively. The data suggest that RPVu and RPVa are correctly named as strains of the same serotype and that GPV is sufficiently different from either RPV strain to be considered a distinct BYDV type. The coat protein and movement protein genes of GPV are very dissimilar to SGV. The polymerase sequences of RPVu, RPVa and GPV show close affinities with those of the sobemo-like luteoviruses and little similarity with those of the carmo-like luteoviruses. The sequences of the coat proteins, movement proteins and the polymerase segments of BYDV serotypes, other than RPV and GPV, form a cluster that is separate from their counterpart sequences from dicot-infecting luteoviruses. The RPV and GPV isolates consistently fall within a dicot-infecting cluster. This suggests that RPV and GPV evolved from within this group of viruses. Since these other viruses all infect dicots it seems likely that their common ancestor infected a dicot and that RPV and GPV evolved from a virus that switched hosts from a dicot to a monocot.

Australia↗

PubMed1998

Inhibition of cell proliferation in head and neck squamous cell carcinoma cell lines with antisense cyclin D1.

Cyclin D1 and cyclin G are essential regulatory factors in the progression of the cell cycle from G0 through G1 and S phase. Aberrations in expression of these cyclins may lead to dysregulated cellular proliferation that could result in neoplasia. Amplification and overexpression of cyclin D1 have been observed in many human cancers, whereas cyclin G is a new cyclin recently described in osteosarcoma cells. This study was performed to determine whether these cyclins were amplified in head and neck squamous cell carcinoma (HNSCC) tumors. Polymerase chain reaction of DNA extracted from 22 HNSCC primary tumors and three HNSCC cell lines did not reveal amplification of cyclin D1 in any of the tumor samples. Southern blot analysis identified amplification of cyclin D1 in a single tumor. Amplification of cyclin G was not observed in any of the tumors by Southern blot hybridization with a cyclin G probe. HNSCC cell lines transfected with antisense cyclin D1 were tested for cell proliferation by the incorporation of 3H-thymidine into cells grown in serum-free media. By 72 hours of incubation, there was a greater than 30% reduction in proliferation of cells transfected with antisense cyclin D1 as compared with non-transfected control cells. The results indicate that cyclin D1 may play an important role in the growth and proliferation of HNSCC cells.

Adult↗

PubMed1998

Tonsillar carcinoma: analysis of treatment results.

OBJECTIVE: Early stage squamous cell carcinoma of the tonsil is amenable to treatment by either surgery or radiation therapy as a single modality, with comparable rates of local control. Unfortunately, manifestation of the disease at an early stage is infrequent, and surgery or radiation alone is less successful in controlling advanced disease. This study was conducted to elucidate the optimal treatment plan for advanced stages of tonsillar carcinoma and to identify significant risk factors for development of recurrence or failure of local control. METHOD: We reviewed the UCLA experience with treatment of all stages of tonsillar carcinoma between 1970 and 1990. RESULTS: Actuarial local control rates were 70% for T1, 72% for T2, 50% for T3, and 0% for T4 at 5-year follow-up. Local control and overall survival rates were compared according to the type of treatment rendered for each stage. CONCLUSIONS: From our analysis we conclude that aggressive combination therapy with surgery and radiation yields significantly higher local control rates for stages 3 and 4 tonsillar carcinomas. The advantages and disadvantages of preoperative versus postoperative radiation therapy are discussed.

Adult↗

PubMed1997

Deletion analysis of the p16/CDKN2 gene in head and neck squamous cell carcinoma using quantitative polymerase chain reaction method.

BACKGROUND: Recently, the p16/CDKN2/MTS1 gene in the 9p21-22 region has been offered as a candidate tumor suppressor gene. We examined the frequency of hemizygous and homozygous deletions of p16/CDKN2 in head and neck squamous cell carcinoma (HNSCC) using a quantitative polymerase chain reaction (PCR) method. DESIGN: Twenty-one HNSCC and 12 corresponding normal DNA samples were examined for deletion of p16/ CDKN2 using PCR amplification and fluorescent quantification of DNA. All tumor and normal DNA samples were also amplified with fluorescein-labeled primers for a control DNA marker on chromosome 8p (D8S265). The ratios of the observed fluorescence of the p16/CDKN2 and 8p PCR products were compared. SETTING AND PARTICIPANTS: Patients with HNSCC scheduled to undergo surgical resection of their tumors were recruited. After the specimen was removed, a portion of the tissue was snap frozen for further DNA extraction. RESULTS: Eight tumors (38%) had p16/CDKN2-D8S265 ratios of greater than 0.75; 8 tumors (38%), from 0.25 to 0.75; and 5 tumors (24%), of less than 0.25, the average ratio in this last group being 0.06. CONCLUSIONS: These ratios suggest a higher rate of homozygous deletion than previously reported and significant probable hemizygous deletion of the p16/CDKN2 gene in HNSCC.

Carcinoma, Squamous Cell↗

PubMed1997

Suppressive factor or factors derived from head and neck squamous cell carcinoma induce apoptosis in activated lymphocytes.

Our laboratory has previously identified a soluble factor derived from head and neck squamous cell carcinoma that impairs lymphocyte proliferative responses in vitro. This study further investigates the nature of the interaction between these factors and T lymphocytes. The proliferative activity of phytohemagglutinin-stimulated peripheral blood lymphocytes and the Jurkat T-cell line was significantly suppressed (>50%) by the supernatants of 13 (41.9%) of 31 recently explanted head and neck squamous cell carcinoma samples. A characteristic morphologic appearance of these suppressed cells and ladderlike pattern of DNA fragmentation on gel electrophoresis indicated that the suppressive supernatants were inducing or predisposing T cells to apoptotic death. This apoptosis-inducing activity may be similar to that previously described in a suppressive supernatant obtained from an esophageal carcinoma cell line. These results shed further light on the mechanism behind a soluble immunosuppressive factor or factors produced by head and neck squamous cell carcinoma.

Adult↗

PubMed1996

Extranodal Rosai-Dorfman disease of the head and neck.

Rosai-Dorfman disease is a rare, idiopathic, benign histiocytic proliferation usually seen in younger patients. Massive lymphadenopathy most commonly involves the cervical lymph nodes, with a predominant infiltration of sinusoidal histiocytes. Nearly half of the patients will have extranodal involvement, 75% occurring in sites in the head and neck. Three cases of extranodal Rosai-Dorfman disease of the head and neck involving the nose, paranasal sinuses, and parotid gland are presented. The clinical presentation, histologic characteristics, radiographic findings, and treatment of the disease are discussed. Because of the scarcity of cases, the clinical and histopathologic features of this disease may be overlooked. Familiarity with its relatively frequent clinical manifestations in the head and neck, as well as with the diagnostic histopathology, should preclude confusion with other disease entities.

Adult↗

PubMed1995

Amyloidosis of the head and neck. A clinicopathologic study of the UCLA experience, 1955-1991.

OBJECTIVE: To characterize the otolaryngologic manifestations of amyloidosis; classify patients with amyloidosis by specific location and type of underlying disease; and compare disease presentation and long-term outcome in these patients. DESIGN: Retrospective review of biopsy specimens recorded as amyloidosis. SETTING: Tertiary care referral center serving a diverse patient base. PATIENTS: Of 141 patients with biopsy-verified amyloidosis who met the inclusion criterion for the study, 27 (19%) had head and neck manifestations. OUTCOME MEASURES: Good functional outcome and survival of patients with amyloidosis. RESULTS: The tongue was the most commonly affected site of the head and neck. Distinct differences exist in functional outcome and long-term survival in patients with the localized form of amyloidosis when compared with patients with systemic amyloidosis. CONCLUSION: Because amyloidosis often affects the head and neck, otolaryngologists need to be familiar with this disease.

Adult↗

PubMed1995

Pediatric rhabdomyosarcoma of the head and neck.

The optimal treatment for most patients with pediatric rhabdomyosarcoma (RMS) of the head and neck has been shown to be a combination of surgery, chemotherapy and radiation therapy. A retrospective review of patients seen at our institution is presented to analyze the impact of multimodality treatment on survival in 32 pediatric RMS patients. Sixty-five percent (21/32) of the patients were disease free at the most recent follow-up. The 5 year disease free survival was 57% (17/30). Combined modality treatment in 25 patients consisting of chemotherapy, radiation therapy and surgical resection (in 5 patients) rendered 18 (72%) patients free of disease. Only 1 of 7 (14%) patients who underwent surgery alone as primary management was cured. Two of these 7 patients were salvaged, both with combined modality treatment. The Intergroup Rhabdomyosarcoma Study (IRS) protocols have resulted in increased survival in pediatric patients with RMS of the head and neck. Our results reflect the significant improvement since the IRS study was completed.

Adolescent↗

PubMed1995

Clinical and pathologic distinction between primary and metastatic mucosal melanoma of the head and neck.

Metastatic mucosal melanoma is extremely rare. Only 0.6% to 9.3% of patients with cutaneous malignant melanoma will have metastases to the mucosa of the upper aerodigestive tract. The records of all patients with mucosal melanoma of the head and neck at the University of California, Los Angeles Medical Center during the past 30 years were reviewed. Patients with primary tumors were separated form those with metastatic involvement from a cutaneous primary site. These two groups were compared for differences in clinical symptoms, histopathologic findings, treatment, and survival characteristics. Frequent sites of metastatic involvement included the base of tongue and nasal cavity. These arose from a variety of cutaneous sites including the trunk and extremities and, in most instances, did not arise until 2 to 7 years after the initial cutaneous lesion. Most of those with metastases to the head and neck mucosa had disseminated disease. The histopathologic distinction between the two groups is described with photomicrographs. Junctional activity in the overlying or adjacent mucosa distinguishes primary mucosal melanoma from metastatic disease, in which the overlying mucosa is usually intact. This difference is useful in determining workup and treatment options. Aggressive surgical resection is suggested in treatment of primary melanomas, whereas surgery is at best palliative in those with metastatic disease.

Adult↗

PubMed1995

Characterization of lymphocyte subpopulations in Warthin's tumor.

Cell suspensions from six Warthin's tumors (WTs) were characterized with fluorescence-labeled cell cytometry. WT lymphocyte subsets were identified with monoclonal antibodies directed against lymphocyte-associated cell antigens including T lymphocyte subsets, B lymphocytes, and natural killer (NK) cells. Results showed that T cell proportions were 58% and B cell proportions were 39%. The T cell helper:cytotoxic-suppressor ratio was 5.7:1 and the B to T cell ratio was 0.8:1. NK cells represented 1.3% of cells. When compared to peripheral blood lymphocytes (PBLs) in the same patients, statistically significant differences were noted between PBLs and WT lymphocytes in the percentage of B lymphocytes (P < .01), T cytotoxic-suppressor lymphocytes (P < .02), NK cells (P < .01), and in the ratios of B to T lymphocytes (P < .01) and T helper to T cytotoxic-suppressor lymphocytes (P < .03). Comparing these data to retrospective data on lymphocyte distribution in normal and reactive lymph nodes, the epithelial component does not appear to exert a local effect on the lymphoid component of WT.

Adenolymphoma↗

PubMed1994

Characterization and sequencing of cDNA clone encoding the phloem protein PP2 of Cucurbita pepo.

Direct N-terminal amino acid sequencing of the phloem protein 2 (PP2) from 3-month old Cucurbita pepo L. (pumpkin), purified by SDS-PAGE and blotted onto PVDF membrane, showed that the protein had a blocked N-terminus. However, after in situ cleavage of the polypeptide in a gel slice by cyanogen bromide, 75 residues of sequences on two cyanogen bromide fragments were determined. An oligonucleotide probe based on this amino acid sequence was used to screen a cDNA library, constructed from mRNA of 3-5-day old seedling hypocotyls, in lambda ZAP II. A cDNA clone (p11A) predicted an amino acid sequence of 218 residues, in full agreement with the sequences determined for two CNBr fragments of PP2, and suggests that the N-terminus of the protein is a blocked methionine residue which is cleaved off by CNBr. Two additional cDNA clones were sequenced but no heterogeneity in the PP2 sequence was found. The deduced amino acid sequence of C. pepo differs in nine residues from the recently published sequence of Cucurbita maxima (Bostwick et al., Plant Cell 4 (1992) 1539-1548). Southern blot showed that PP2 is encoded by a gene family with a relatively large number of members (estimated as 7-15 per haploid genome).

Amino Acid Sequence↗

PubMed1994

Role of myosin light-chain phosphorylation in guinea pig gallbladder smooth muscle contraction.

In acetylcholine (ACh)-stimulated gallbladder smooth muscle, we have previously shown that phosphorylation of the 20,000-Da myosin light chains is necessary for the initiation of contraction, that myosin is stably phosphorylated at steady state, and that dephosphorylation of cross bridges is not necessary for the slowing of cross-bridge cycling rates during the period of steady-state isometric stress. The present studies were undertaken to determine whether 1) K+ (60 or 80 mM) or cholecystokinin (CCK, 10(-8) M) stimulation is accompanied by changes in myosin light-chain phosphorylation in gallbladder smooth muscle and 2) dephosphorylated noncycling cross bridges exist in K(+)- or CCK-stimulated gallbladder smooth muscle. Isometric stress, isotonic shortening velocity, and myosin light-chain phosphorylation were determined during contraction with K+ or CCK. Steady-state isometric stress was reached within 2.5 min of stimulation with K+ or CCK and was maintained for the duration of the stimulation. Stimulation with K+ or CCK was associated with rapid increases in myosin light-chain phosphorylation and maintenance of myosin light-chain phosphorylation during the stimulation. In contrast, isotonic shortening velocity was maximal at 1 min of stimulation with either K+ or CCK and then declined significantly to values that were only 26-32% of the peak velocity. These data, along with data from previous experiments with ACh, suggest that myosin light-chain phosphorylation is essential in the initiation of contraction in gallbladder smooth muscle, regardless of the source of Ca2+ or of the contractile agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗