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Biomedical subjects

W A Schroeder

Publications and source records attributed to W A Schroeder.

At least 19 recordsLinked to original sources

Malignant neoplastic disease of the parotid lymph nodes.

OBJECTIVES: To review the management and outcome of patients with malignant neoplastic disease of the parotid lymph nodes excluding those with primary salivary gland tumors. STUDY DESIGN: Retrospective review of 14 patients who had malignant parotid lymph nodes from metastatic cutaneous malignancies, direct extension from primary cutaneous malignancies, or lymphoproliferative disorders. METHODS: Charts were reviewed from three institutions and tabulated for age, gender, histopathology, treatment, and outcome. RESULTS: Fourteen patients met the criteria for study. Ten patients had neoplastic nodes from cutaneous malignancies. Seven involved squamous cell carcinoma, two were metastatic from melanoma, and one was metastatic from basal cell carcinoma. Four patients had involvement from lymphoproliferative disorders. CONCLUSIONS: Metastatic disease to the parotid nodes or direct extension to nodes from primary cutaneous malignancy demonstrates a poor prognosis in this series. Prognosis of lymphoproliferative disorder is more favorable.

Aged↗

Microbial carotenoids.

Carotenoids occur universally in photosynthetic organisms but sporadically in nonphotosynthetic bacteria and eukaryotes. The primordial carotenogenic organisms were cyanobacteria and eubacteria that carried out anoxygenic photosynthesis. The phylogeny of carotenogenic organisms is evaluated to describe groups of organisms which could serve as sources of carotenoids. Terrestrial plants, green algae, and red algae acquired stable endosymbionts (probably cyanobacteria) and have a predictable complement of carotenoids compared to prokaryotes, other algae, and higher fungi which have a more diverse array of pigments. Although carotenoids are not synthesized by animals, they are becoming known for their important role in protecting against damage by singlet oxygen and preventing chronic diseases in humans. The growth of aquaculture during the past decade as well as the biological roles of carotenoids in human disease will increase the demand for carotenoids. Microbial synthesis offers a promising method for production of carotenoids.

Antioxidants↗

Singlet oxygen and peroxyl radicals regulate carotenoid biosynthesis in Phaffia rhodozyma.

Carotenoids have recently received considerable interest because of their potential in delaying or preventing degenerative diseases such as arteriosclerosis, cancer, and aging. In this study we show that the active oxygen species singlet oxygen (1O2) and peroxyl radicals differently affect carotenoid composition and biosynthesis in the yeast Phaffia rhodozyma. Photochemical generation of 1O2 with rose bengal or alpha-terthienyl induced carotenoid accumulation. In contrast, peroxyl radicals derived from t-butylhydroperoxide (tBOOH) or H2O2 decreased the content of astaxanthin and increased beta-carotene by approximately 4-fold, suggesting end product feedback regulation by astaxanthin or inhibition of biosynthetic enzymes. 14C labeling of carotenoids during oxidative stress supported the possibility of end product regulation. Carotenoids were bleached by 8 mM tBOOH within 6 h when carotenogenesis was inhibited by thymol. When treated with peroxides, a previously unreported pigment in P. rhodozyma was formed. The carotenoid had a mass of 580 Da and a molecular formula of C40H52O3. Chemical derivatizations combined with mass and absorbance spectroscopy tentatively identified the carotenoid as dehydroflexixanthin (3,1'-dihydroxy-2,3,3',4'-tetradehydro-1',2'-dihydro-beta,psi-caro tene-4-one). This study provides the first report of induction of astaxanthin biosynthesis by 1O2, probable feedback control by astaxanthin, and the oxidative degradation of astaxanthin to novel pigments in P. rhodozyma.

Carotenoids↗

Post tonsillectomy hemorrhage: a ten-year retrospective study.

Tonsillectomy remains one of the most common surgical procedures performed in the world. One of the most significant complications is postoperative hemorrhage. Though most bleeding often can be controlled with local anesthesia in an office or emergency room, some patients require return to the operating room for general anesthesia to control the hemorrhage. A ten-year retrospective study was done to review patients who required return to the operating room for general anesthesia for control of hemorrhage. Variables investigated include age, gender, time of surgery, onset of hemorrhage, season of the year, and the amount of blood loss noted during initial surgery. Seven of the 756 patients (.93%) required a second general anesthesia to control hemorrhage. Seasonal and gender predilictions are noted in this study. Recent trends in tonsillectomy are reviewed. Postoperative hemorrhage creates anxiety, prolongs morbidity, and increases health care cost. Limiting this complication is clearly in the best interest of both patient and surgeon.

Adolescent↗

Post tympanostomy otorrhea.

Myringotomy with placement of ventilation tubes is the most common pediatric otolaryngologic procedure in the United States. Otorrhea is generally recognized as the most common complication of this procedure. The current study is a three-year prospective evaluation of post tympanostomy otorrhea to determine what variables might be associated with otorrhea. Analysis of patients from a predominantly rural population is presented.

Age Distribution↗

Closure of conchal defects. The hinged retroconchal island flap with overlying cutaneous transposition flap.

BACKGROUND: Conchal defects secondary to surgical procedures or trauma often cannot be closed primarily. OBJECTIVE: Tissue transfer for closure of defects must be tension free and not create a postauricular sulcus too shallow. METHODS: A retroconchal island flap provides such a closure. A rhomboid transposition flap used to provide closure of the donor site retains the depth of the posterior sulcus. RESULTS: The closure of the defect heals well within 4-6 weeks even in presence of scar tissue from multiple prior surgeries. CONCLUSION: The retronconchal island flap is a simple, reliable technique to close the defect of the concha without sacrificing the natural depth of the posterior sulcus.

Aged↗

Intranasal melanoma.

Malignant melanoma is most commonly associated with cutaneous malignancies of sun-exposed skin, but melanoma also occurs in the mucosal surfaces of the head and neck. The symptoms of intranasal melanoma are most often associated with benign conditions that patients often ignore during the early course of the disease. Benign symptoms that persist require thorough evaluation to exclude neoplastic disease in which timely diagnosis and early treatment offers the best prognosis.

Female↗

Beta S-gene-cluster haplotypes in sickle cell anemia: clinical implications.

Restriction endonuclease analysis was used to detect alpha-gene deletions and to determine the haplotypes in the DNA of the beta S-gene-cluster [Benin, Central African Republic (CAR), and Senegal] in 221 patients with sickle cell anemia (SS). The clinical expression of SS was modified by the beta S-gene-cluster polymorphisms and the alpha-gene status (alpha-thalassemia-2). The overall risk of soft tissue organ failure caused by the obliterative sickle vasculopathy (including stroke, renal failure, chronic lung disease with cor pulmonale, leg ulcers, and young adult death) was increased threefold in those with a CAR haplotype and was decreased in those with a Senegalese chromosome (p = 0.003). In the presence of a Senegalese haplotype, the patient's health is better, and with the CAR haplotype it is always worse. With the Benin, it is intermediate. Acute recurrent clinical events including hospitalized sickle cell crisis, bone infarction, and infection are decreased in frequency in those with a Senegalese haplotype. The risk of most acute events including acute chest syndrome is equivalent in those with Benin or CAR haplotypes. In the United States, alpha-thalassemia-2 is co-inherited randomly among the beta S-gene-cluster haplotypes. Acute events occurring during childhood are minimally effected by this co-inheritance. The risk of soft tissue organ failure is decreased. After the age of 20 years, painful episodes of the lumbar dorsal area are increased in patients who had alpha-thalassemia-2 in association with degenerative bone disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Sickle Cell↗

Increase in Gs and cyclic AMP generation in HIT cells. Evidence that the 45-kDa alpha-subunit of Gs has greater functional activity than the 52-kDa alpha-subunit.

Cyclic AMP accumulation in response to forskolin, cholera toxin, or isoproterenol is dramatically increased in HIT T-15 cells, a clonal cell line of Syrian hamster pancreatic islet beta cells, as a function of passage number. Forskolin and cholera toxin elevate cyclic AMP levels 5- to 10-fold higher in later passages (87-100) than in earlier passages (70-80). A similar phenomenon is observed with isoproterenol (10 microM) which increases cyclic AMP levels 56-fold in older HIT cells (passage 94), whereas only marginally stimulating cyclic AMP production in younger cells (passage 70-82). To determine whether a change in the stimulatory or inhibitory guanine nucleotide regulatory proteins, Gs or Gi, was responsible for these observations, ADP-ribosylation of HIT cell membranes with cholera toxin and pertussis toxin was examined. All passages contained two cholera toxin substrates at 52 and 45 kDa. The amount of 52 kDa did not appear to change with passage number, but the amount of 45 kDa increased in the later passages (89 and 94). The ratio of 45 to 52 kDa cholera toxin substrate, as determined by densitometric analysis, increased from 0.1 in passages 70, 75, and 82 to 0.45 at passage 89. No passage related changes in a 40-kDa pertussis toxin substrate were observed. An increase in the amount of the 45-kDa alpha-subunit of Gs was confirmed on immunoblots using antisera specific for the alpha-subunits of Gs. The amount of functional Gs present in various HIT cell passages was examined by determining the extent to which extracts from HIT cell membranes reconstituted guanine nucleotide-sensitive adenylyl cyclase in S49 cyc- membranes. Extracts derived from passage 94 reconstituted three to four times more adenylyl cyclase activity in cyc- membranes than extracts from passages 70, 75, and 82. These data indicate that an increase in functional Gs in later passages may be the underlying cause for the increased responsiveness to isoproterenol and forskolin in later passages. These data also suggest that functional differences exist between the Gs alpha-subunits, with the smaller 45-kDa subunit being more efficacious in coupling to cyclic AMP synthesis than the larger 52-kDa subunit. This is a departure from the commonly held view that the two subunits have similar efficacies in stimulating adenylyl cyclase.

Adenylate Cyclase Toxin↗

Nonblack patients with sickle cell disease have African beta S gene cluster haplotypes.

Of 18 nonblack patients with sickle cell disease, 14 had sickle cell anemia, 2 had hemoglobin SC disease, and 2 had hemoglobin S-beta o-thalassemia. The beta s gene cluster haplotypes that were determined in 7 patients were of African origin and were identified as Central African Republic, Central African Republic minor II, Benin, and Senegal. The haplotype Central African Republic minor II was present on the beta o-thalassemia chromosome in 2 patients. None of 10 patients whose alpha-gene status was determined had alpha-thalassemia-2. These data strongly support the concept that the beta s gene on chromosome 11 of these individuals is of African origin and that the alpha-gene locus on chromosome 16 is of white or native American origin. The clinical severity of the disease in these nonblack patients is appropriate to their haplotype without alpha-thalassemia-2 and is comparable with that of black patients. All persons with congenital hemolytic anemia should be examined for the presence of sickle cell disease regardless of physical appearance or ethnic background.

Adult↗

The influence of fetal hemoglobin on the clinical expression of sickle cell anemia.

The variable levels of HbF in sickle cell anemia reflect the heterogeneous genetic mix of the beta s-gene-cluster haplotypes and coinheritance of alpha-thalassemia-2 in American SS patients. Clinical severity is less when the level of HbF reaches 20% or 1.2 g/dl or more. The coinheritance of alpha-thalassemia-2 not only increases the intracellular red cell water but modifies the HbF level in accordance with the beta-cluster haplotype. In general, the SS patient with at least one Senegalese haplotype who does not have a CAR haplotype in trans, has a significantly greater probability of maintaining HbF above 20%. This is in part related to the genetic control of the G gamma HbF locus. Such a patient is protected from arteriolar vasculopathy and subsequent major organ destruction. Much of this but perhaps not all of the better health of patients with a Senegalese haplotype can be attributed to the elevation of G gamma HbF. The coinheritance of alpha-thalassemia-2 further decreases the risk of major morbidity of the soft tissues but increases the risk of avascular necrosis of the bony skeleton. Although these heterozygous Senegal patients are healthier, eventually most, in time, will show the deleterious effect of HbS as retinopathy and avascular necrosis usually beginning after age 30 and sickle nephropathy after age 40. Because of the age-specific effect, the onset of the sickle vasculopathy is delayed by nearly 20 years in the Sen/Ben patient with increased G gamma HbF as compared to those with a CAR haplotype or the homozygous Benin. Lifetime elevation of HbF above 20% modifies the severity of disease expression and provides relative protection to the patient with sickle cell anemia.

Anemia, Sickle Cell↗

Beta-cluster haplotypes, alpha-gene status, and hematological data from SS, SC, and S-beta-thalassemia patients in southern California.

The beta-gene-cluster haplotype and alpha-gene status were determined for 221 patients with sickle cell anemia, 41 with SC disease, and 21 with S-beta-thalassemia. Among SS patients, eleven beta S haplotypes were found in 21 combinations. Three haplotypes--the Benin (Ben) [---+-], the Central African Republic (CAR) [+---+], and the Senegal (Sen) [+- ]--comprise 61%, 21%, and 10% of the chromosomes, respectively. Cleavage at the Xmn I site 5' to the G gamma gene was observed only when the Senegalese arrangement was present. The linear correlation which exists between the absolute value of the G gamma chains and the Hb F for each haplotype combination suggests a feed-back mechanism which controls the G gamma to A gamma ratio and thus the Hb F level (or vice versa). The A gamma T chain was present with specific haplotypes [++-++] and [++-+-]. Heterozygous or homozygous alpha-thalassemia-2 was present in 36% of the SS patients and was randomly distributed among beta S-gene-cluster haplotypes. The variable levels of hemoglobin, MCV, Hb F, G gamma chains, and Hb A2 are in response to the heterogeneous genetic mix of the beta S-gene-cluster haplotypes and alpha-thalassemia-2 in American patients with sickle cell anemia. The influence of alpha-thalassemia-2 on the level of Hb F is dependent on the beta S-cluster haplotype. Hb A2 levels increased with decrease in the number of alpha genes. Among SC and S-beta-thalassemia patients the beta-cluster polymorphisms on the beta S chromosome were those commonly associated with the African origins of beta S haplotype. The haplotype [+--+-] was present on the C chromosome in 90% of the cases. Most beta-thalassemia chromosomes had haplotypes that matched the common African polymorphisms. An alpha-gene deletion was found in 29% of the SC and S-beta-thalassemia patients.

Adolescent↗

Malignant clear cell hidradenoma of the lip.

An interesting variety of cutaneous tumors of the head and neck, tumors of the eccrine differentiation, are seldom recognized. The most recent reports of these tumors appear in the dermatologic literature, probably due to the majority of them being located in the trunk and the extremities. Malignant varieties of these tumors do exist and must be treated as aggressively as more common tumors of the head and neck region. Tumors with eccrine differentiation are among a large variety of cutaneous tumors that present in the head and neck. These tumors are far less common than basal cell and squamous cell carcinomas of the head and neck. Malignant clear cell hidradenomas, a variant of the more common benign clear cell hidradenoma, is one such type of tumor of the eccrine differentiation. This is a rare tumor seldom reported in sites of the head and neck. A case of a 47-year-old white male with such a tumor of the lower half of his lip is presented. This report is particularly concerned with the histopathology of the tumor, its unique etiology, and the applicability of the lip switch flap (Stein-Abbe-Estlander) in the reconstruction of the surgical defect following total tumor excision.

Adenoma, Sweat Gland↗