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Biomedical subjects

T L Johnson

Publications and source records attributed to T L Johnson.

At least 19 recordsLinked to original sources
PubMed1999

A skin blister method to study epidermal nerves in peripheral nerve disease.

Skin is a reservoir of sensory and autonomic nerve fibers that are potential indicators of peripheral nerve disease. Biopsies of skin have shown that sensory nerves in the most superficial layer of skin, the epidermal nerve fibers (ENFs), are reduced in patients with polyneuropathy. This report describes a minimally invasive skin blister method to isolate, image, and obtain quantitative analysis of ENFs. Blisters are made by applying a suction capsule to skin. The epidermal roof of the blister is excised, immunostained, whole mounted, and analyzed for ENF number and distribution. A reduction in number and abnormal distribution of ENFs are early indicators of peripheral nerve disease. Illustrations of skin blister and skin biopsy specimens from patients with different types of peripheral nerve disorders are included. These patients were chosen because their findings demonstrate the complementary information obtained by the blister and biopsy methods and the potential of the blister procedure to evaluate single nerve lesions and polyneuropathy and to follow the progress of ENF degeneration and regeneration.

Adult↗
PubMed1999

Partial tracheal obstruction due to chondromas in ball pythons (Python regius).

Over a 9-mo period, three adult ball pythons (Python regius) (one male, two females) were evaluated for severe dyspnea. Partial obstructions of the tracheal lumen were identified radiographically and/or visualized with a 3.0-mm rigid laparoscope inserted into the tracheal lumen in all three snakes. Administration of systemic antibiotics and nebulization resulted in partial improvement of the dyspnea. In two snakes, the tracheal lesions were removed with a rigid laparoscope and a flexible biopsy instrument inserted into the tracheal lumen. The other snake died and was necropsied. Histologically, the lesions from two snakes were determined to be benign chondromas. The chondromas were composed of a variably disorganized chondroid matrix populated by quiescent, normal-appearing chondrocytes within lacunae, although the chondrocytes were increased in density compared with normal hyaline cartilage and contained rare mitotic figures. The tracheal masses in one snake grew by expansion, not invasion, and were focally continuous with a mineralized cartilage tracheal ring, suggesting a benign nature. This is the second report of tracheal chondroma in ball pythons. Tracheal chondromas are exceedingly rare in humans and domesticated animals, suggesting a possible predisposition of ball pythons for this neoplasm.

Animals↗
PubMed1998

Health care needs of medically underserved women of color: The role of the Bureau of Primary Health Care.

The Bureau of Primary Health Care (BPHC) was developed to increase access to comprehensive primary and preventive health care and to improve the health status of medically underserved populations. Approximately 43 million Americans fall into this category, and the majority are poor, female, young, and uninsured. Under the Public Health Services Act, BPHC does not provide direct services, but rather assist local communities in identifying populations at risk of poor health outcomes and helps these communities through various programs. One of the newest initiatives of BPHC is the Office of Minority and Women's Health, developed with a mission to help reduce the disparities in the health status of women of racial and ethnic minority populations. This article outlines these disparities and discusses proposals for reducing them.

Ethnicity↗
PubMed1997

Physician gender and women's preventive services.

OBJECTIVE: To determine whether the gender of women's regular physicians, controlling for physician specialty, is associated with women's receiving key preventive services within recommended intervals. DESIGN: Cross-sectional, nationally representative women's health telephone survey conducted by Louis Harris and Associates in February and March 1993 for The Commonwealth Fund. PARTICIPANTS: A total of 2,525 women in the continental United States, > or = 18 years old, including oversamples of African-American and Hispanic women. MAIN OUTCOME MEASURES: Receipt of each of five preventive services (blood pressure reading, Pap smear, cholesterol test, clinical breast examination, and mammogram) within specific periods. RESULTS: Physician gender makes a significant difference for two specialty areas and for three preventive services. Patients of women family or general practitioners are more likely than the patients of men to have received a Pap smear or a blood cholesterol test within the last 3 years, and the patients of women internists are more likely to have received a Pap test. Physician gender is associated with a higher likelihood of mammography, but this finding was limited to patients ages 40-49 of women family or general practitioners. Physician gender does not affect receipt of blood pressure screening or breast examination. CONCLUSIONS: Analyses reveal limited evidence that physician gender affects women's receipt of preventive services. Physician specialty appears to be a more powerful predictor of preventive services received. The limited evidence for a physician gender effect, however, is relevant for those women who rely on a family or general practitioner or an internist for regular care.

Adolescent↗
PubMed1996

Structure-activity relationships of the antimalarial agent artemisinin. 5. Analogs of 10-deoxoartemisinin substituted at C-3 and C-9.

Novel 3- and 9-substituted analogs (4-19) of 10-deoxoartemisinin, 3, were prepared from the corresponding known lactones by one-pot reduction with sodium borohydride and boron trifluoride etherate. Reproducibility problems associated with this heterogeneous reaction were encountered on small reaction scales, and thus alternative methodology was sought for this reduction. Conversion of the lactones to tetrahydropyrans via the corresponding intermediate lactols was made more reproducible using a two-step sequence involving low-temperature reduction with diisobutylaluminum hydride followed by deoxygenation with boron trifluoride etherate in the presence of triethylsilane. In this manner, 10-deoxoartemisinin (3) could be obtained from artemisinin (1) in greater than 95% overall yield. All analogs were tested in vitro against W-2 and D-6 strains of Plasmodium falciparum. Several of the analogs were much more active than the natural product (+)-artemisinin (1) or 10-deoxoartemisinin (3). Conventional structure-activity relationships are discussed in relation to the bioassay data.

Animals↗
PubMed1996

Endometrial metaplasia as a source of atypical glandular cells in cervicovaginal smears.

Cytohistological correlation of abnormal cervicovaginal smears indicates that endometrial metaplasia may be associated with the presence of atypical glandular cells. Seven patients with histologically confirmed endometrial metaplasia had atypical glandular cells in cervicovaginal smears; five smears were interpreted as being suspicious for endometrial adenocarcinoma. Most of the patients (5/7) were postmenopausal (mean age = 61.3 years), and three of seven patients had abnormal vaginal bleeding. The corresponding endometrial tissue specimens demonstrated various combinations of eosinophilic, papillary, squamous, and tubal metaplasia; in one case tubal metaplasia occurred in association with an endometrial polyp. Cytologic features noted in the cervicovaginal smears from all seven patients were similar and included small clusters of atypical glandular cells in an inflammatory background. Intracytoplasmic vacuoles were often present, and a moderate degree of aniosonucleosis was noted. Enlarged glandular nuclei contained finely granular chromatin and distinct nucleoli. The differential diagnosis of atypical glandular cells includes endometrial hyperplasia and well-differentiated endometrial adenocarcinoma. The atypical cells associated with endometrial metaplasia were characterized by a relatively low N:C ratio and evenly distributed chromatin. In contrast, the cells of endometrial carcinoma typically demonstrate increased N:C ratios and irregularly distributed chromatin.

Adenocarcinoma↗
PubMed1996

Metaplastic breast carcinoma: a cytohistologic and clinical study of 10 cases.

Metaplastic breast carcinomas (MBC) account for < 5% of breast malignancies and have an uncertain prognostic significance. The tumors tend to grow rapidly, and most are negative for hormone receptors. Adenosquamous carcinomas and various types of carcinosarcomas may be classified as MBC. We evaluated the cytologic, histologic, and clinical parameters of 10 MBC to determine important diagnostic features of these tumors. A cytologic diagnosis of MBC, based on the identification of two distinct malignant components, was made preoperatively in five of 10 (50%) cases, and retrospectively in two additional cases; two specimens were inadequately cellular. Poorly-differentiated adenocarcinoma was the most frequently encountered component of MBC. It is recommended that malignant breast aspirates be carefully scrutinized for multiple neoplastic components. Our series of MBC differs from previous reports in that two cases presented as inflammatory breast cancer, one case was pregnancy-associated, and there was a higher incidence of estrogen and progesterone receptor positivity. No cancer-related deaths occurred during a mean follow-up period of over 6 yr.

Adult↗
PubMed1995

Squamous cell carcinoma of the cervix metastatic to an ovarian Brenner tumor.

Metastatic tumors account for approximately 10 to 15% of surgically excised ovarian malignancies (Semin Diagn Pathol 8:250-276, 1991). Although the majority of tumors arise within the female genital tract, cervical cancer is a rare source of metastasis to the ovary. Cervical carcinomas with ovarian involvement are usually advanced lesions with lymph node involvement (Am J Obstet Gynecol 166:50-53, 1992; Cancer 71:407-418, 1993). We present a case of Stage IIB squamous cell carcinoma of cervix metastatic to an ovarian Brenner tumor. Our purpose in presenting this case is to report useful histologic features in the diagnosis of this rare combination of tumors. We are not aware of any other published reports of this entity.

Brenner Tumor↗
PubMed1995

Update on the surgical pathology of the vulva.

Recent developments in the surgical pathology of the vulva include updated classifications of non-neoplastic epithelial disorders and vulvar intraepithelial neoplasias. Several histologic variants of vulvar squamous cell carcinoma (SCC) with distinct clinicopathologic features have been described. The concept of superficially invasive vulvar SCC continues to be a complex issue. The use of standardized surgical pathology reports and checklists are recent developments in surgical pathology.

Basal Cell Carcinoma↗
PubMed1994

Complexes of yeast RNA polymerase II and RNA are substrates for TFIIS-induced RNA cleavage.

In the absence of DNA, purified yeast RNA polymerase II can bind RNA to form a binary complex. RNA in such RNA-RNA polymerase complexes undergoes reactions previously thought to be unique to nascent RNA in ternary complexes with DNA, including TFIIS-dependent cleavage and elongation by 3'-terminal addition of NMP from NTP. Both of these reactions are inhibited by alpha-amanitin. Hence, by several criteria the RNA in binary complexes is bound to the polymerase in a manner quite similar to that in ternary complexes in which the catalytic site for nucleotide addition is positioned at or near the 3'-OH terminus of the RNA. These findings are consistent with a model for the RNA polymerase ternary complex in which the RNA is bound at the 3' terminus through two protein-binding sites located up to 10 nt apart.

Amanitins↗
PubMed1994

Prevalence of HPV 16 and 18 DNA sequences in CIN III lesions of adults and adolescents.

Adolescents may be more susceptible to cervical human papillomavirus (HPV) infections and may have more rapid progression of cervical intraepithelial neoplastic (CIN) lesions than adults. We evaluated Papanicolaou (Pap) smears and cervical tissue specimens from a consecutive series of 25 adolescent (age 15-20 yr) and 17 adult (age 35-40 yr) patients with a histologic diagnosis of CIN III. The study patients were all Detroit residents enrolled in a health maintenance organization (HMO) affiliated with Henry Ford Hospital. The cervical tissue specimens were evaluated for HPV 6b/11, HPV 16, and HPV 18 using agarose gel electrophoresis and Southern hybridization following polymerase chain reaction (PCR) DNA amplification. While the small sample size precluded testing for statistical significance, HPV 16 and/or HPV 18 DNA was detected in specimens from 21/25 (84%) adolescents compared to 12/17 (71%) adults (odds ratio [OR] = 2.2; 95% confidence interval [CI] = 0.49-9.74). The relationship between adolescence and HPV infections appears to be stronger for HPV 18 and mixed HPV 16/18 infections (OR = 5.6; 95% CI = 0.7-42.4) than for HPV 16 infections (OR = 1.93; 95% CI = 0.4-8.8). None of the cervical specimens contained HPV 6b/11 DNA. Oral contraceptive (OC) use was associated with HPV infection in patients with CIN III, but there was no association between cigarette smoking and HPV infection. The effect of OC use on the relationship of age and HPV could not be evaluated due to small sample size. The effects of previous sexually transmitted disease (STD) on the relationship of age and HPV were assessed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Diagnosis of low back pain, secondary to prostate metastasis to the lumbar spine, by digital rectal examination and serum prostate-specific antigen.

OBJECTIVE: To present a case in which the initial diagnosis of spinal metastasis secondary to prostate cancer was established from findings of the digital rectal examination (DRE) and serum prostate-specific antigen (PSA) analysis. CLINICAL FEATURES: A 79-yr-old black male was seen after suffering from low back pain for 1 month. Urinary frequency and nocturia were associated symptoms. Abnormal findings on the DRE and serum PSA determination suggested a preliminary diagnosis of spinal metastases secondary to prostate cancer. Subsequent referral for biopsy and bone scan yielded the final diagnosis of prostate adenocarcinoma with spinal metastasis. Radiographs of the lumbosacral spinal region were inconclusive and results of routine laboratory tests (CBC, ESR, U/A) were within normal limits. INTERVENTION AND OUTCOME: The patient was referred for medical palliation of his condition. A bilateral orchiectomy was performed along with oral antiandrogen administration. At a consultation 8 months postoperatively, he reported to be free of pain. CONCLUSION: At least 40% of newly diagnosed cases of prostate cancer can be expected to have metastasized at the time of initial discovery. Routine use of DRE and serum PSA in patients complaining of low back pain who are at high risk for prostate cancer is recommended. However, mass screening with DRE or PSA in asymptomatic males is not recommended. There are no prospective studies showing evidence that mass screening for prostate cancer will reduce the mortality or morbidity rates from the disease.

Adenocarcinoma↗
PubMed1993

Gentamicin toxicosis in a North American cougar.

This report documents nephrotoxicosis in a North American cougar (Felis concolor) caused by gentamicin overdose and describes a method of calculating drug dosages by metabolic scaling for species in which pharmacokinetic studies have not been performed. Determining drug dosages by metabolic scaling can decrease the likelihood of administering inappropriate drug doses in exotic animals.

Alopecia↗
PubMed1993

Cytologic features of metastatic transitional cell carcinoma.

Cytologic preparations containing metastatic transitional cell carcinoma (MTCC) from 18 sites in 16 patients were reviewed to determine characteristic morphologic features. The patient group included 13 males and 3 females with a mean age of 66 years. Primary TCC occurred in the bladder (14), kidney (1), and ureter (1); nearly all the primary tumors were poorly differentiated and most were invasive at the time of diagnosis. The cytologic specimens were derived from lymph nodes (6), liver (4), serous fluids (2), pelvic soft tissue (2), subcutaneous nodules (2), and lung (1). One patient presented with MTCC in Pap smears. Cytologically MTCC presented as loosely cohesive, moderate to markedly pleomorphic cells which occurred singly and in syncytial clusters. The malignant cells were usually large with abundant granular or fibrillar cytoplasm and the cell borders were generally distinct. Most nuclei were large and hyperchromatic with irregularly distributed granular chromatin and prominent nucleoli. The most distinctive features were the presence of spindled, pyramidal, and/or racquet-shaped malignant cells with eccentric nuclei and cytoplasmic features of both squamous and glandular differentiation including endoplasmic/ectoplasmic interfaces and intracytoplasmic vacuoles. Although clinical history is most useful in the diagnosis of MTCC, these morphologic features in cytologic preparations of malignant epithelial neoplasms may be helpful. In the absence of a known primary TCC, it is doubtful that a definite cytologic diagnosis could be made; however, the characteristic cell shapes and cytoplasmic features may be suggestive of MTCC.

Aged↗
PubMed1993

Worsening tricuspid regurgitation following pericardiectomy for constrictive pericarditis.

We describe two cases of worsening tricuspid regurgitation following surgical pericardiectomy for constrictive pericarditis. Both patients demonstrated hemodynamic profiles characteristic of constrictive pericarditis on cardiac catheterization. They also had moderate tricuspid regurgitation as judged by Doppler echocardiography. The worsening tricuspid regurgitation observed was a result of postoperative right ventricular dilatation. These cases demonstrate the importance of determining tricuspid valvular function in patients with constrictive pericarditis prior to pericardiectomy; however, the hemodynamic changes that result in worsening tricuspid regurgitation may not be present for weeks.

Aged↗
PubMed1992

Use of an implant for intraosseous infusion as supportive therapy for a Vietnamese pot-bellied pig with urethral obstruction caused by a polyp.

A Vietnamese pot-bellied pig with a urethral polyp was supported by total parenteral nutrition given through an intraosseous implant. Peripheral vascular access was difficult to establish and maintain in this anorectic pig, so a pediatric intraosseous implant was placed in the left tibia. Surgical repair of the urethra was not considered possible, and alternative techniques of a functional bypass were unacceptable to the owners, so euthanasia was elected. Histologic examination of the urethra revealed a polypoid structure believed to be similar to benign congenital polyps described in young boys.

Animals↗
PubMed1992

Effects of combining transforming growth factor beta and 1,25-dihydroxyvitamin D3 on differentiation of a human osteosarcoma (MG-63).

Transforming growth factor beta (TGF beta) and 1,25-dihydroxyvitamin D3 (1,25D3), when added simultaneously to a human osteosarcoma cell line, MG-63, induce alkaline phosphatase activity 40-70-fold over basal levels, 6-7-fold over 1,25D3 treatment alone, and 15-20-fold over TGF beta treatment alone. TGF beta and 1,25D3 synergistically increased alkaline phosphatase specific activity in both matrix vesicles and plasma membrane isolated from the cultures, but the specific activity was greater in and targeted to the matrix vesicle fraction. Inhibitor and cleavage studies proved that the enzymatic activity was liver/bone/kidney alkaline phosphatase. Preincubation of MG-63 cells with TGF beta for 30 min before addition of 1,25D3 was sufficient for maximal induction of enzyme activity. Messenger RNA for liver/bone/kidney alkaline phosphatase was increased 2.1-fold with TGF beta, 1.7-fold with 1,25D3, and 4.8-fold with the combination at 72 h. Human alkaline phosphatase protein as detected by radioimmunoassay was stimulated only 6.3-fold over control levels with the combination. This combination of factors was tested for their effect on production of three other osteoblast cell proteins: collagen type I, osteocalcin, and fibronectin. TGF beta inhibited 1,25D3-induced osteocalcin production, whereas both factors were additive for fibronectin and collagen type I production. TGF beta appears to modulate the differentiation effects of 1,25D3 on this human osteoblast-like cell and thereby retain the cell in a non-fully differentiated state.

Alkaline Phosphatase↗