Lead poisoning from the use of Indian folk medicines.
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Adult↗
Biomedical subjects
L Johnson
Publications and source records attributed to L Johnson.
Staging equine seminiferous tubules by Nomarski optics in unstained histologic sections and in tubules mounted in toto to reveal the spermatogenic wave.
Nomarski optics were used to identify stages of the spermatogenic cycle of seminiferous tubules in sectioned tissue or in whole dispersed tubules and to characterize the equine spermatogenic wave. Embedded tissues were sectioned at 20 microns. Whole dispersed tubules were obtained by enzymatic digestion of thin slices of fresh testis. Dispersed tubules were fixed, dehydrated in graded levels of alcohol, infiltrated with Epon, and mounted in toto on glass slides. Stages of the spermatogenic cycle could be identified under Nomarski optics in both histologic sections and tubules mounted in toto. Stage dependent nuclear chromatic and cytoplasmic changes in spermatogonia, spermatocytes, and spermatids were evident. Spermatid development included chromatin condensation, nuclear elongation, acrosomal development from the Golgi and proacrosomic granules, migration of the annulus and mitochondrial alignment, and the transient appearance of the chromatoid body and manchette. Both nuclear and cytoplasmic details of Sertoli cells were revealed. In tubules mounted in toto, the spermatogenic wave along the length of the tubules occurred as a consecutive set of stages occupying small regions along the tubular length. The spermatogenic wave in the horse is more similar to that of humans than that of rats. The combination of enzymatic isolation of seminiferous tubules and identification of spermatogenic stages by Nomarski optics facilitates examination of the spermatogenic wave in species whose tubules are tightly bound and not easily teased apart.
Animals↗
Patients with severe forms of inherited epidermolysis bullosa exhibit decreased lymphokine and monokine production.
Peripheral blood mononuclear cells (PBMC) from patients with severe forms of inherited epidermolysis bullosa (EB) are deficient in functions governing cellular immunity. Very low levels of interferon-gamma (IFN-gamma), interleukin-1 (IL-1), and interleukin-2 (IL-2) were produced in vitro by PBMC from patients with severe forms of EB (recessive dystrophic and dominant dystrophic) as compared to sex- and age-matched controls. Lymphokine production by PBMC from patients with junctional EB was somewhat greater than that from patients with dystrophic forms of EB but was significantly less than that from controls. The production of interferon-alpha was not found to be altered in the severe forms of EB. The PBMC from dystrophic types of EB were also deficient in production of tumor necrosis factors (TNF-alpha and TNF-beta). The degree of the reduction in immune functions was directly related to the severity of skin involvement, with recessive dystrophic EB having the lowest level of cytokine production. This reduced production of monokines and lymphokines may be partially responsible for the progression of cutaneous infections to septicemia and for the metastasis of cutaneous squamous cell carcinomas in patients with severe forms of dystrophic EB.
Adolescent↗
Serum amylase in patients treated with lithium.
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Aged↗
Incidence, severity and time course of ROP in a randomized clinical trial of vitamin E prophylaxis.
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Antioxidants↗
Silicone rubber fossa implant removal via partial arthrotomy followed by arthroscopic examination of the internal surface of the fibrous capsule.
Thirteen temporomandibular joints were examined arthroscopically for evaluation for fibrous encapsulation of silicone elastomer disk replacement implants. Partial arthrotomies were performed with removal of silicone rubber implants, followed by arthroscopic examination of the internal surfaces of the fibrous capsule as a pseudodisk and to verify the continuity of the fibrous barrier between the condyle and the fossa.
Adult↗
Dental diagnosis and treatment (DDx & Tx): interactive videodisc patient simulations for dental education.
Judgement skills and critical thinking in dentistry are developed through: (1) a systematic approach to gathering and processing information, and (2) an essential amount of practical experience. A new system of interactive videodisc patient simulations titled 'Dental Diagnosis and Treatment' or 'DDx & Tx' has been developed to provide students or practicing dentists an opportunity to develop and practice their critical thinking skills. The DDx & Tx system consists of patient simulation software, a laser-reflective videodisc with its accompanying database, a patient simulation management system, and documentation. An authoring tool is under development. Faculty-authored simulations require students to gather information, formulate diagnoses, order appropriate treatments and properly sequence those treatments. The students' performance is automatically scored and a critique is provided as a review.
Computer Simulation↗
Studies in rat liver perfusion for optimal harvest of hepatocytes.
Pediatric liver transplantation is successful but donor scarcity is a major limitation. We are studying hepatocyte transplantation as an alternative to provide functional hepatic replacement. This report details the study of rat liver perfusion for optimal harvest of hepatocytes and cell implantation. We performed 128 rat liver perfusions using a technique modified from the two-step enzymatic perfusion described by Seglen. We examined variations in the perfusion, rate, time, antegrade versus retrograde, pulsatile versus continuous flow, temperature, collagenase type, and variables of buffer composition. We have found optimal cell yield and viability under the following conditions: in situ perfusion, continuous flow at 25 cc/min, retrograde perfusion via the inferior vena cava, water bath temperature 38 degrees C, Boerhinger-Mannheim collagenase using a nonoxygenated HEPES based perfusion buffer, pH 7.4, for the initial perfusion and the same buffer with 4.8 mmol/L CaCl2 for the collagenase perfusion. These conditions consistently generate cell harvests of 500 to 700 x 10(5) cells/g of liver tissue with cell viability between 85% and 95%.
Animals↗
Maternal and fetal plasma vitamin E to total lipid ratio and fetal RBC antioxidant function during gestational development.
Placental transfer of vitamin E was investigated from 19 to 35 weeks of gestation by analysis of fetal and maternal blood samples for total tocopherol, total lipids, and fetal red blood cell antioxidant reserves. Fifty-two fetal blood samples were obtained under ultrasonographic guide by percutaneous umbilical blood sampling. Thirteen were from fetuses with gestational age less than or equal to 22 weeks (x serum vitamin E = 0.4 +/- 0.14 mg/dl), 12 were from fetuses at 23-27 weeks gestation (x serum vitamin E = 0.4 +/- 0.21 mg/dl), and 27 were from fetuses with gestational age 28-38 weeks (x serum level = 0.37 +/- 0.18). Total lipid levels ranged from 140 to 216 mg/dl. Maternal plasma vitamin E concentrations correlated significantly with concurrent values in the fetus. There were no significant differences in serum vitamin E levels or vitamin E to total lipid ratio in samples from early, mid, or late gestation in either the mother or fetus. Red blood cell antioxidant reserve on samples from 18 fetuses were grossly abnormal by three different functional assays. On the basis of these data, placental transfer of vitamin E appears to be relatively constant through advancing gestation. Red blood cell antioxidant reserve is uniformly low.
Erythrocytes↗
Increased germ cell degeneration during postprophase of meiosis is related to increased serum follicle-stimulating hormone concentrations and reduced daily sperm production in aged men.
Aged men, known to have high serum gonadotropin levels and reduced spermatogenic potential, were used to study the relationship between serum follicle-stimulating hormone (FSH) and germ cell degeneration. Serum hormones were measured from blood obtained at autopsy. Phase-contrast cytometry was used to enumerate germ cells in homogenates of fixed testes from 13 younger (24-51 yr) and 14 aged (69-90 yr) men. The developmental steps of spermatogenesis during which germ cells degenerate were determined by comparing potential daily sperm production based on primary spermatocytes with daily sperm production based on two different types of spermatids. During spermiogenesis, there was no significant degeneration in the younger or aged men. During postprophase of meiosis, aged men had more (p less than 0.01) germ cell degeneration, significantly lower (p less than 0.05) serum testosterone, and greater (p less than 0.01) serum FSH than did younger men. Germ cell degeneration during postprophase of meiosis was negatively correlated (p less than 0.01) to daily sperm production and significantly (p less than 0.01) related to serum concentrations of FSH. As revealed in these aged men, meiotic germ cell degeneration has a direct effect on daily sperm production and is significantly related to serum FSH concentrations.
Adult↗
Production of transgenic mice and application to immunology and autoimmunity.
During the last decade, transgenic animal technology has assumed an increasingly important role as a critical tool in animal biology, biomedical research, and pharmaceutical development. This technology allows virtually any fragment of DNA large enough to contain an entire gene to become integrated into the germline of the recipient animal. The newly inserted DNA will be inherited like endogenous genes, and will be expressed as RNA and protein at tissue locations and abundance depending on regulatory elements attached to the coding DNA. It is possible to clone a particular gene, change a regulatory coding sequence, and reinsert the gene to determine the effect of the change on expression and function of the gene.
Allergy and Immunology↗
Chelation therapy and cardiac status in older patients with thalassemia major.
Cardiac dysfunction is the most common cause of death in patients with homozygous beta-thalassemia. We studied a group of 10 older patients (mean age 17.5 years) with and without preexisting cardiac dysfunction who had begun chelation therapy on the average of 10 years after regular transfusions were initiated. Over the 4-year study period, two patients were noncompliant with deferoxamine therapy. Their clinical status and cardiac function deteriorated, and both died with evidence of arrhythmia and congestive heart failure. The remaining eight patients were compliant. Despite a drop in mean serum ferritin from 3,814 +/- 577 (SE) ng/ml to 1,056 +/- 146 ng/ml (p less than 0.01), two patients with preexisting cardiac problems and one patient without preexisting heart disease developed further abnormalities. Of the three patients whose status declined, one ultimately improved with alternative chelation therapy. These data suggest that for a few older patients, improvement or stabilization of cardiac status may not be achieved with improved compliance and reduced serum ferritin levels. For these patients, new approaches appear to be warranted. On the other hand, we have demonstrated that in most cases, older patients who began chelation therapy years after transfusions began have benefited from compliance with standard subcutaneous deferoxamine regimens.
Adolescent↗
Coding and noncoding sequences at the 3' end of yeast histone H2B mRNA confer cell cycle regulation.
Yeast (Saccharomyces cerevisiae) histone mRNA synthesis is tightly regulated to the S phase of the cell division cycle as a result of both transcriptional and posttranscriptional regulation. We focused on the role of posttranscriptional control in histone H2B1 gene (HTB1) regulation and studied a portion of the HTB1 message required for cell-cycle-specific accumulation. The 3' end of the HTB1 gene containing a 17-amino-acid coding sequence and entire noncoding sequence was fused to the bacterial neomycin phosphotransferase II gene (neo) under control of the GAL1 promoter. The expression of the endogenous and chimeric HTB1 genes was analyzed during the yeast cell cycle. As yeast cells entered a synchronous cell cycle following release from alpha-factor arrest, the level of GAL1-promoter-controlled neo-HTB1 message increased approximately 12-fold during S phase and dropped to basal level when the cells left S phase. This indicates that the 3' end of the HTB1 mRNA is capable of conferring cycle-specific regulation on a heterologous message. Deletion analysis of the 3' end showed that the signal for cell cycle control of HTB1 mRNA includes contiguous coding and noncoding sequences surrounding the stop codon. This differs from the situation in mammalian cells, whose posttranscriptional regulation of histone genes is mediated through a short sequence containing a stem-loop structure near the very terminus of the untranslated 3' end.
Base Sequence↗
Effect of LY171883 on endotoxin-induced lung injury in pigs.
We evaluated the role of sulfidopeptide leukotrienes as mediators of endotoxin-induced respiratory failure in pigs. Escherichia coli endotoxin (055-B5) was infused intravenously into anesthetized 10- to 14-wk-old pigs at 5 micrograms/kg the 1st h followed by 2 micrograms.kg-1.h-1 for 3 h in the presence and absence of LY171883, a specific leukotriene D4 (LTD4)/LTE4 receptor antagonist. Endotoxin caused hemoconcentration, granulocytopenia, decreased cardiac index, systemic hypotension, pulmonary hypertension, increased pulmonary vascular resistance, bronchoconstriction, hypoxemia, increased permeability of the alveolar-capillary membrane, pulmonary edema, and increased plasma concentrations of thromboxane B2 (TxB2), prostaglandin F2 alpha (PGF2 alpha), and 6-keto-PGF1 alpha. LY171883 did not modify endotoxin-induced cardiopulmonary and hematologic abnormalities, except for a modest attenuation of pulmonary hypertension (at 1 h) and increased pulmonary vascular resistance (at 1-2 h). Ex vivo stimulation of whole blood with calcium ionophore caused large increases in plasma concentrations of TxB2, PGF2 alpha, and LTB4. These increases were not significantly modified in blood derived from pigs treated with LY171883, indicating no inhibition of cyclooxygenase or 5-lipoxygenase. We conclude that LTD4 and LTE4 are not important mediators of endotoxin-induced lung injury in anesthetized pigs, although they may contribute modestly to pulmonary vasoconstriction.
Acetophenones↗
Isolation and staging of horse seminiferous tubules by transillumination.
Stages of the spermatogenic cycle in the horse were determined by trans-illumination of enzymically isolated, seminiferous tubules and were verified by whole-mounted tubules observed by Nomarski optics and by conventional histology. Isolated tubules were obtained from young (less than 2 years) and adult (4-10 years) horses by enzymic digestion. Dispersed tubules were separated into three different groups based on the presence, size, and intensity of a dark region in the centre of the tubules: (1) pale--homogeneously light, (2) spotty--light on the periphery with a wide spotty region in the central two-thirds, or (3) dark--an intensely dark, narrow region through the central one-third. Seminiferous tubules from young stallions separated easily, but were only of the homogeneously light pattern as they lacked mature spermatids. After observation by Nomarski optics and bright-field microscopy, pale tubules under transillumination largely contained Stages I and II, spotty tubules contained Stages V and VI, and dark tubules contained Stages VII and VIII of the spermatogenic cycle. In-vitro incorporation of [3H]thymidine in spermatogonia and preleptotene/leptotene primary spermatocytes of these tubules confirmed the viability of germ cells in isolated tubules, and ultrastructural analysis confirmed excellent preservation of normal structure of seminiferous epithelium in isolated tubules. Hence, segments of seminiferous tubules in specific stages of the spermatogenic cycle can be obtained from enzymically digested horse testes when viewed by transillumination.
Animals↗
101 oesophageal cancers: a surgeon uses radiotherapy.
One hundred and one consecutive patients with oesophageal cancer, cancer of the cardia and gastric cancer extending upwards from the stomach to the oesophagus were treated from 1979 to 1985 with a policy that included radiotherapy treatment for 58. This heterogeneous group, which was considered together as oesophageal cancer, was subdivided according to anatomical location, histology and pretreatment staging. Those patients who could be treated surgically by a resection and anastomosis performed below the diaphragm were excluded. Thirty-five had surgery which was either an oesophagogastrectomy or oesophagojejunostomy with an intrathoracic anastomosis, except for two who were nonresectable. Eight patients were to ill or refused treatment. The role of radiotherapy was assessed in three groups: i. Operable squamous cell carcinoma of the oesophagus was treated by radical radiotherapy (22) with a 46% 1-year and 14% 5-year survival. ii. Inoperable squamous cell carcinoma of the oesophagus was given radical or palliative radiotherapy (25) with a 16% 1-year and 4% 5-year survival. iii. Non-resectable adenocarcinoma of the stomach or oesophagus was treated palliatively by radiotherapy to debulk the intraluminal tumour (11), all of whom had symptomatic relief of dysphagia. The results of radical radiotherapy for operable squamous cell carcinoma of the oesophagus were similar to the best results achieved by surgical resection in other series in which there is comparable staging. Radiotherapy should be included in the treatment options for oesophageal cancer.
Adenocarcinoma↗
HIV preventive medicine services and public health interventions: the Bethesda experience.
A basic Public Health approach to the Human Immunodeficiency Virus (HIV) epidemic has been considered by many to be the most appropriate initial strategy against the spread of this infection. Comprehensive Preventive Medicine services were implemented at Naval Hospital Bethesda, which utilized a sexually transmitted disease (STD) model and included: counseling and education; sexual contact interviews and spouse evaluations; Blood Bank Look Back tracking of donated blood; reporting of notifiable diseases; and screening of transfusion recipients, STD cases, and other at-risk populations. This coordinated approach is highly efficient and capable of evaluating the increasing numbers of HIV-positive individuals.
Acquired Immunodeficiency Syndrome↗