Pathogenesis of slipped capital femoral epiphysis: current concepts

Since Ambrose Paré in 1572 initially described what is believed to be the first case of slipped capital femoral epiphysis (SCFE), a virtual plethora of unproven theories has evolved in the ensuing years. The most currently popular theories embrace a framework of biomechanical events versus biochemical events having impact at the time of puberty. The zone of slipping always occurs primarily through the zone of hypertrophy in a corrugated undulating fashion. All investigative studies show that the growth plate at the time of puberty is weakened in SCFE. The final common pathway appears to be a mechanical failure of the growth plate, due to a weakened state, to resist displacement. The commonly encountered large body mass coupled with an increasingly oblique physis lying in a relative degree of retroversion creates a mechanical environment that, coupled with delicate alterations in the hormonal balance of thyroid hormone, growth hormone, testosterone, and estrogen, render the plate intrinsically suspectible to displacement by rather innocuous forces occurring in a shear plane. Ultrastructure studies of SCFE demonstrate a significant alteration in anatomy and physiology in all active metabolic areas of the growth plate. It is the author's concept that SCFE is a generalized metabolic disorder of puberty resulting from a series of pubertal mishaps with a multifactorial basis ordinarily caused by a relative imbalance of hormones, coupled with biomechanical events.

Systemic immunization induces protective CD4+ and CD8+ T cell-mediated immune responses in murine Listeria monocytogenes meningoencephalitis

The immune mechanisms underlying immunization-induced protection of mice from lethal central nervous system (CNS) listeriosis were evaluated by immunohistochemistry, flow cytometry of leukocytes isolated from the brain, reverse transcription-polymerase chain reaction analysis of intracerebral (i.c.) tumor-necrosis factor-alpha, interferon-gamma, interleukin (IL)-2, IL-1 beta, IL-10, granulocyte/macrophage colony-stimulating factor, and inducible nitric oxide synthase mRNA expression, and T cell depletion experiments. The data demonstrate that active immunization of mice prior to an i.c. infection with Listeria monocytogenes prevents the development of a fatal necrotizing encephalitis and accelerates the recruitment of an increased number of alpha beta T cell receptor (TcR)+ CD4+ and CD8+ T cells, gamma delta TcR+ T cells, B cells, granulocytes and macrophages to the brain compared to non-immunized animals. In addition, immunization induced a pronounced activation of i.c. macrophages and microglial cells as shown by an increased expression of MHC class II antigens. In parallel, transcript levels for all cytokine mRNA analyzed were higher in the brains of immunized mice. The protective effects of immunization were completely abolished by depletion of CD4+, CD8+, or both T cell subsets. All groups of T cell-depleted immunized mice developed a fatal necrotizing encephalitis with an increased i.c. bacterial load. In addition, cytokine mRNA synthesis was significantly impaired. The severity of disease was only slightly different between CD4+, CD8+ and CD4+/CD8+ T cell depleted mice, indicating that both subsets of T cells are required for an effective i.c. immune response to L. monocytogenes. This is in marked contrast to systemic listeriosis, and points to CNS-specific features of the immune response.

A seroprevalence study of herpes virus type 2 infection in Israeli women: implications for routine screening

The aim of the study was to obtain data on the prevalence of herpes simplex virus type 2 (HSV-2) in selected populations of women and to identify groups that might benefit from routine prenatal screening. The prospective seroprevalence study was performed in 1,921 women in Israel during the period 1986-90. Four different population groups of women 17-60 years old were included. Groups 1 and 2 comprised 1,214 healthy female government employees and kibbutz and moshav residents, and Groups 3 and 4 comprised 707 Jewish and non-Jewish women with gynecological complaints. HSV-2 antibody in the sera were studied by the microneutralization method. In the healthy women (groups 1 and 2), the prevalence of antibodies to HSV-2 was 2-3%. Genital HSV-2 asymptomatic shedding was 1%. In the women with gynecological complaints (groups 3 and 4) the prevalence of antibodies to HSV-2 was 10% in Jewish and 16% in non-Jewish women. These data support the conclusion that there is no justification for routine prenatal HSV-2 screening in Israel in a healthy female population.

C-erbB-2 expression and codon 12 K-ras mutations both predict shortened survival for patients with pulmonary adenocarcinomas

We evaluated the prognostic significance of p185c-erbB-2 expression and ras gene mutations in all patients diagnosed with a pulmonary adenocarcinoma between 1982 and 1985 at the University of Iowa. p185c-erbB-2 expression was detected in 15 cases (34%). A ras gene mutation was found in 16 cases (36%) and all were in codon-12 of K-ras. No N-ras mutations were identified. Both p185c-erbB-2 expression and a K-ras mutation were found only in codon-12 and present in six cases (14%). By univariate analysis p185c-erbB-2 expression was associated with shortened survival (P = 0.02) while the presence of a K-ras mutation was not (P = 0.16). Multivariate analysis by the Cox proportional hazards model, controlling for patient age and tumor stage, also continued to identify p185c-erbB-2 expression as an independent unfavorable prognostic factor (P = 0.01). In this model a K-ras mutation also approached significance as a poor prognostic indicator (P = 0.06). The impact of both p185c-erbB-2 expression and a K-ras mutation on survival was additive and highly significant (P = 0.004). This additive nature suggests that together these two markers identify a high-risk population of lung adenocarcinoma patients that may benefit from aggressive therapy.

Health beliefs about cancer. Among the Luiseño Indians of California

Among numerous Luiseño Indians of San Diego County, California, cancer is considered to be any tumor or growth that is possibly life threatening. A medical anthropology research project reveals that current and former Luiseño cancer patients share illness causation theories distinct from those of their kin. The patients believe their bouts with cancer stem from genetic predilection and/or God's will. In contrast, other Luiseño band members who do not have cancer assert that almost all cancer is caused by either 1.) chemical pollutants in the air, water, and food; or 2.) prior biomedical treatments that have gone awry. Imbalances of both natural and bodily elements are generally traced to particular culprits. This paper will detail these variances of Luiseño cancer etiologies and their impact on prevention policies.

Inhibition of human lung cancer cell line growth by an anti-p185HER2 antibody

p185HER2, the product of the c-erbB-2 or HER2 gene, is a membrane-bound tyrosine kinase that has structural similarity to the epidermal growth factor receptor. Functionally, interaction of HER2 with its ligand or p185HER2 antibodies affects the growth and differentiation of HER2-expressing breast cancer cell lines. As p185HER2 is also expressed in human lung cancers and human lung cancer cell lines, we hypothesized that these cell lines would also respond to p185HER2 antibodies. To test this hypothesis, we cultured human non-small cell lung cancer cell lines in the presence of a p185HER2 monoclonal antibody called 4D5. 4D5 inhibited the growth of p185HER2-expressing cell lines in a dose-dependent fashion. In addition, BEAS.2B, a p185HER2-nonexpressing bronchial epithelial cell line, was transfected with the HER2 cDNA, resulting in high-level p185HER2 expression, and growth of BEAS.HER2 was now inhibited by 4D5 exposure. Mechanistically, 4D5 appeared to have a weak agonist effect on the tyrosine kinase function of p185HER2, as exposure of p185HER2-expressing cell lines to 4D5 resulted in increased p185HER2 phosphorylation. Furthermore, inhibition of tyrosine kinase function with Genistein reversed the 4D5-induced growth inhibition. Therefore, 4D5 can regulate the growth of p185HER2-expressing lung cancer cell lines through agonist effects on p185HER2.

Molecular-clinical correlations in children and adults with fragile X syndrome

INTRODUCTION

Fragile X syndrome is the most commonly known inherited form of mental retardation. The intellectual abilities range from a normal IQ with learning disabilities to severe mental retardation. In males, there is a tendency for IQ decline in childhood. The purpose of this study was to correlate variations of the molecular cytosine guanine guanine (CGG) amplification in the fragile X mental retardation-1 (FMR-1) gene with the clinical findings, including IQ and physical features.

METHODS

Full-scale IQ and cytogenetic results in 116 individuals with the FMR-1 mutation were studied. The IQ testing was performed with age-appropriate standardized tests. Physical features were summarized in a physical index score for each patient. The FMR-1 results were determined with the OX1.9 probe and the following system was used: P1 indicates premutation; P2, large premutation to small full mutation; P3, full mutation; and P4, mosaic.

RESULTS/CONCLUSIONS

The findings showed that those females with a small insert in the P1 range had a significantly higher IQ than other heterozygotes (P2, P3, and P4 categories). P4 males had a significantly higher IQ than P2 or P3 males. In cross-sectional age comparisons, the slope of the IQ decline was greater in P2 males than in P4 or P3 males.

Design and synthesis of a CD4 beta-turn mimetic that inhibits human immunodeficiency virus envelope glycoprotein gp120 binding and infection of human lymphocytes

Poor bioavailability, rapid degradation, antigenicity, and high cost often limit the use of proteinaceous pharmaceuticals. One goal of structural biochemistry is the reduction of complex molecules to small functional units that are amenable to high-resolution structural analysis and rapid modification. The dissection of complex proteins into small synthetic conformationally restricted components is an important step in the design of low molecular weight nonpeptides that mimic the activity of the native protein. We have developed a reverse-turn mimetic system to explore peptide and protein structure-function relationships. We now report the design and synthesis of a small molecule (M(r) 810, as its trifluoroacetate salt), water soluble, proteolytically stable mimetic of residues Gln40-Thr45 of the complementarity-determining 2-like region of CD4. This mimetic has a low micromolar Kd for human T-lymphotropic virus type IIIB gp120 and reduces syncytium formation.

A mechanism of resistance to glucocorticoids in multiple myeloma: transient expression of a truncated glucocorticoid receptor mRNA

Despite their widespread use, little is known of either the mechanism of action of glucocorticoids in the treatment of multiple myeloma or why patients ultimately become resistant to their therapeutic effects. Here, we address these issues by examining the direct effects of the glucocorticoid dexamethasone (DEX) on a hormone-sensitive clone (MM.1S) of a human multiple myeloma line and compare them with those of its hormone-resistant counterpart (MM.1R). MM.1S expresses approximately 50,000 glucocorticoid receptors (GR) per cell, the full-length 7.1-kb GR mRNA at high levels, and is lysed by DEX. DEX-induced cytolysis is effectively blocked by the glucocorticoid antagonist, RU 486, indicating the specificity of this response for the GR. In contrast to MM.1S, MM.1R is not lysed by hormone, has little hormone-binding activity, and expresses the 7.1-kb GR mRNA at low levels. Interestingly, we have found that two distinct phenotypes emerge from MM.1R with increasing periods of growth in culture. The first or "early" form, MM.1Re, expresses high levels of a variant GR mRNA of 5.5 kb that has a deletion in its 3' end. With further growth in the presence or absence of selective media, the expression of this transcript is repressed, resulting in the second or "late" phenotype characteristic of MM.1RL. No discernible differences in the organization of the genomic GR sequence in DEX-sensitive and -resistant cells were detectable by Southern analysis, suggesting that no gross deletions, rearrangements, or allelic variations in the genomic sequence account for the resistant phenotypes of MM.1R.

Biotin uptake, utilization, and efflux in normal and biotin-deficient rat hepatocytes

Biotin uptake, utilization, and efflux were studied in normal and biotin-deficient cultured rat hepatocytes. Biotin-deficient cells accumulate about 16-fold more biotin than do normal cells when incubated with a physiological concentration of biotin for 24 h. This difference is due to the greater amount of protein-bound biotin relative to free biotin in biotin-deficient hepatocytes, and is attributable to the presence of more apocarboxylases in deficient cells. The rate of biotin uptake and the rate of activation of the carboxylases, acetyl-CoA carboxylase, pyruvate carboxylase, propionyl-CoA carboxylase, and beta-methylcrotonyl-CoA carboxylase, are proportional to the concentration of exogenous biotin. Increases in carboxylase activities are proportional to the concentration of biotin only at exogenous biotin concentrations of less than 410 nM. Concentrations of 410 nM or more biotin increase carboxylase activities to normal or near normal. Biocytin inhibits biotin uptake at very high concentrations, whereas desthiobiotin and lipoic acid have no effect. Biocytin in the medium results in carboxylase activation either intracellularly or extracellularly by conversion to biotin by biotinidase. Investigation of the efflux of biotin from normal and biotin-deficient cells preincubated with the vitamin showed greater retention of biotin by biotin-deficient cells than by normal cells over 24 h. Retention of free biotin is similar in biotin-deficient and normal cells. The greater amount of biotin retained by biotin-deficient cells is accounted for by the greater amount of bound biotin in these cells. These results suggest that the free and bound biotin pools are independently regulated. The ready loss of free biotin from these cells has implications for the treatment of inherited, biotin-responsive carboxylase deficiencies.

Inner medullary collecting duct Na(+)-H+ exchanger

Cells from the inner medullary collecting duct (IMCD) exhibit Na(+)-H+ exchange. The present studies were performed to address certain important characteristics of this process in cultured IMCD cells. First, Na(+)-H+ exchange was found to be present both at 37 degrees C and at 25 degrees C, in contrast to Na(+)-independent H+ extrusion, which was only observed in some cultures and only at 37 degrees C. Second, with the use of image analysis techniques, virtually all cells in IMCD cultures were demonstrated to possess Na(+)-H+ exchange, whether or not the cells exhibited Na(+)-independent intracellular pH recovery from acid loads. Also, Na(+)-H+ exchange was found to be expressed on the basolateral aspect of these cells, but not on the apical membrane. These properties of IMCD Na(+)-H+ exchange are consistent with a function to regulate intracellular pH rather than mediate transepithelial acid-base transport. Na(+)-H+ exchange in IMCD cells was also compared with that in cultured renal proximal tubule cells. Despite physiologically distinct roles in vivo, Na(+)-H+ exchange in these two cell types in culture was found to be similar with respect to the Km for Na+ and the Ki for 5-(N-ethyl-N-isopropyl)amiloride. These data are consistent with functionally similar (if not identical) processes mediating Na(+)-H+ exchange in these two cell types, but with opposite polarity.

The Tridimensional Personality Questionnaire and the inherited risk for alcoholism

The Tridimensional Personality Questionnaire (TPQ) (Cloninger, 1987c) was administered to four groups of young men. The first group was composed of nonalcoholic sons of male alcoholics with extensive multigenerational family histories of male alcohol abuse. The second was made up of nonalcoholic men with alcoholic fathers. The third group was composed of nonalcoholic men with no family history of alcoholism, taken from the general population. The fourth group contained male undergraduates with no family history of alcoholism. There were no significant differences between the mean scores obtained by members of all four groups on the three major subscales of the TPQ.

Biotin uptake in cultured hepatocytes from normal and biotin-deficient rats

Biotin uptake was studied in isolated cultured hepatocytes of normal and biotin-deficient rats. Biotin uptake was temperature-dependent with respect to physical, but not to chemical, processes, proportional to the exogenous biotin concentration in the medium, independent of pH and sodium ion concentrations of the medium, and uneffected by the presence of structural analogues of biotin or metabolic inhibitors in both normal and biotin-deficient hepatocytes. These results suggest that biotin uptake occurs by a passive, nonmediated, non-energy-dependent mechanism in rat hepatocytes.

Characterization of human endothelial cell urokinase-type plasminogen activator receptor protein and messenger RNA

Human umbilical vein endothelial cells in culture (HUVEC) express receptors for urokinase-type plasminogen activators (u-PA). The immunochemical nature of this receptor and its relationship to u-PA receptors expressed by other cell types is unknown. Cross-linking active site-blocked u-PA to HUVEC lead to an increase in its apparent molecular mass by approximately 40 Kd. The predominant u-PA binding protein isolated from whole cell detergent extracts migrated with a molecular mass of approximately 36 Kd using affinity chromatography. In contrast, when only cell surface proteins were radiolabeled before extraction, the predominant labeled u-PA binding protein isolated migrated with a molecular mass of approximately 46 Kd. Several pieces of evidence suggested that the difference in molecular mass between these two u-PA binding proteins resulted from glycosylation of a single receptor protein. First, a polyclonal antibody against u-PA receptor isolated from phorbol myristate acetate (PMA) stimulated U-937 cells reacted with both the 36- and 46-Kd proteins on Western blotting. Second, the size of the unmodified receptor was estimated by amplifying a full-length cDNA for u-PA receptor from an endothelial cell cDNA library using the polymerase chain reaction (PCR) and oligonucleotide primers corresponding to the DNA sequence of the receptor cloned from transformed human fibroblasts (Roldan et al, EMBO J 9:467, 1990). The size of the cDNA (approximately 1,054 base pairs, bp) and the presence of a single 1.4-kilobase (Kb) mRNA transcript on Northern blot analysis predict an unglycosylated receptor protein of approximately 35 Kd. Third, synthesis of 35S-labeled 46-Kd cell surface receptor protein was inhibited when the cells were grown in the presence of tunicamycin, while the synthesis of the 36-Kd species was unaffected. Moreover, the apparent molecular mass of purified surface-labeled receptor (approximately 46 Kd) was reduced by N-glycanase. These studies suggest that the u-PA receptor on the surface of HUVEC is a glycoprotein derived from a protein of approximately 35 Kd which is similar immunologically to u-PA receptors on other cell types.

Studies of the mechanisms of action of the antiretroviral agents hypericin and pseudohypericin

Administration of the aromatic polycyclic dione compounds hypericin or pseudohypericin to experimental animals provides protection from disease induced by retroviruses that give rise to acute, as well as slowly progressive, diseases. For example, survival from Friend virus-induced leukemia is significantly prolonged by both compounds, with hypericin showing the greater potency. Viremia induced by LP-BM5 murine immunodeficiency virus is markedly suppressed after infrequent dosage of either substance. These compounds affect the retroviral infection and replication cycle at least at two different points: (i) Assembly or processing of intact virions from infected cells was shown to be affected by hypericin. Electron microscopy of hypericin-treated, virus-producing cells revealed the production of particles containing immature or abnormally assembled cores, suggesting the compounds may interfere with processing of gag-encoded precursor polyproteins. The released virions contain no detectable activity of reverse transcriptase. (ii) Hypericin and pseudohypericin also directly inactivate mature and properly assembled retroviruses as determined by assays for reverse transcriptase and infectivity. Accumulating data from our laboratories suggest that these compounds inhibit retroviruses by unconventional mechanisms and that the potential therapeutic value of hypericin and pseudohypericin should be explored in diseases such as AIDS.

An estimate of the number of G regulator proteins activated per excited rhodopsin in living Limulus ventral photoreceptors

Previous work by others on Limulus photoreceptors has shown that application of a variety of guanine nucleotide-binding regulatory protein (G protein) activators produces discrete waves of depolarization similar to those generated by single photos, but smaller in size. We investigated whether these events might originate at a site other than the G protein. Initiation of the events did not depend on the state of the visual pigment, suggesting that the events do not originate at the pigment level. The events could be blocked by the G-protein blocker guanosine 5'-[beta-thio]diphosphate (GDP[betaS]) and thus support the conclusion that these discrete events are due to the activation of G protein itself. Quantitative measurements indicate that the average size of these events is approximately 8 times smaller than that evoked by single photons under the same conditions. Given certain reasonable assumptions, these results imply that the gain of the first stage of transduction in vivo is approximately 8, a value considerably lower than that measured in vitro in vertebrate rods (gain, 100-500). Furthermore, independent evidence for a low first-stage gain in Limulus is derived from the observation that GDP[betaS] barely affects the size of the response to single photons, but greatly reduces the probability that a photon evokes a response. These results can be explained if rhodopsin normally activates only a few G proteins.

Extraction of major acidic Ca2+ dependent phosphoproteins from synaptic membranes

The association of several phosphoproteins with the synaptosomal plasma membrane (SPM) was investigated by phosphorylating SPM fractions from neonatal rat brain in the presence of Ca2+ and then exposing these to a variety of agents. Extraction of the major acidic phosphoproteins, GAP-43, pp40, and pp80, was assessed by two-dimensional gel electrophoresis and fluorography. All three proteins were best extracted from the membrane by high pH and by guanidine hydrochloride. GAP-43 was not extracted in the presence of either low- or high-ionic-strength buffers, reducing agents, or chelating agents; pp80 and pp40, however, showed a significant extraction even under low-ionic-strength conditions. Partition experiments with Triton X-114 revealed an amphiphilic behavior for GAP-43 and a strong affinity for hydrophobic environments for pp80 and pp40. None of the phosphoproteins was released from the membrane by the use of a phosphatidylinositol-specific phospholipase C. The extraction properties of GAP-43, pp80, and pp40 are similar to those of known extrinsic membrane proteins and therefore suggest that these phosphoproteins are peripheral rather than integral to the membrane compartment.

Pneumoconiosis in an elderly dentist

Numerous dusts found commonly in the dental laboratory have been suggested as potential pulmonary hazards. We recently noted a case of severe interstitial pulmonary fibrosis with intraalveolar deposition of unique foreign body inclusions in an elderly dentist. The composition of these particles was shown to be consistent with that of alginate impression powder. This is in contrast to previously reported pneumoconioses in dental workers, which are usually induced by metallic alloys or silicates. Further studies are needed to identify the causes and prevalence of pneumoconiosis in the dental lab.

Anti-complement immunofluorescence establishes nuclear localization of human cytomegalovirus matrix protein

A monospecific, polyclonal antiserum to the 69-kDa matrix protein of human cytomegalovirus (HCMV) was prepared in a guinea pig and used to determine the intracellular distribution of this viral antigen. The resulting antiserum was specific for infected cells as tested by immunofluorescence, and specific for the HCMV matrix protein as determined by "nitrocellulose immunoassay" of electrophoretically separated, infected-cell proteins. Antibodies were reacted with fixed, infected human fibroblasts, and visualized by the anti-complement immunofluorescence procedure to avoid complications arising from the strong IgG Fc binding activity of the infected-cell-specific cytoplasmic inclusion. Results establish that the matrix protein is located in the nucleus, and indicate that it is concentrated in the nucleoplasm rather than within the intranuclear inclusions.

Slipped epiphysis associated with hypothyroidism

Seven cases of slipped capital femoral epiphysis appearing concurrently with juvenile hypothyroidism are reported. This association seems to occur more commonly than the general incidence of slipped capital femoral epiphysis or of juvenile hypothyroidism would suggest, and the thyroid hormone deficiency and a diminished strength of the epiphyseal growth plate of the upper femur appear to be associated. Although concrete scientific data are as yet not available to define clearly the effect of thyroid hormone on the growth plate, the possible pathophysiology is discussed in light of available data.

Phosphorylation, maturational processing, and relatedness of strain Colburn matrix proteins

The intracellular 66,000 D (66K) and 69,000 D (69K) matrix-like phosphoproteins of strain Colburn cytomegalovirus (CMV) have been compared with each other and with their electrophoretic counterparts in the virion. Three lines of evidence indicate that the 66K and 69K proteins are products of separate genes, and that the intracellular and virion species are closely related. First, "pulse-chase" radiolabeling experiments showed that these proteins have separate precursors; that modification of each to the mature form correlated with phosphorylation; and that phosphorylation of the 69K precursor occurred more slowly than that of the 66K precursor, and resulted in a more dramatic slowing of its electrophoretic mobility. Second, comparisons of the 66K and 69K proteins based on partial proteolysis of [35S]methionine-labeled proteins, using V8 protease, and complete proteolysis of [32P]orthophosphate-labeled proteins, using trypsin or Pronase, provided no evidence of sequence relatedness. These analyses also suggested that the distribution of phosphorylated residues differs in the two proteins--clustered for the 69K and more disperse for the 66K. Phosphoamino acid analyses showed only phosphoserine in the 66K protein. The 69K protein contained, in addition to phosphoserine, an electrophoretically faster moving, unidentified spot. And third, immunological comparisons showed these proteins to exhibit little or no antigenic cross-reactivity. They did, however, demonstrate that the nuclear proteins are immunologically cross-reactive with their respective virion counterparts. Additional comparisons of these nuclear and virion proteins established that the virion 69K protein (v69) differs in electrophoretic mobility and net charge from the nuclear 69K protein but that it, as well as the virion 66K protein, has a two-dimensional phosphopeptide pattern similar to its nuclear counterpart.

Effect of chemical stimuli on nerves supplying upper airway muscles

Studies of upper airway resistance suggest that the activity of cranial nerves supplying upper airway muscles changes with chemical drive and that imbalances in the activation of these nerves as compared to the phrenic play a role in causing upper airway obstruction. We assessed the effect of hypoxia and hypercapnia on the activity of the hypoglossal nerve, the recurrent laryngeal nerve, and phrenic nerve in paralyzed anesthetized artificially ventilated dogs. Comparison of hypoglossal and phrenic nerves were also repeated after vagotomy. Both hypoglossal and recurrent laryngeal nerves exhibited increased activity with inspiration. Hypoxia and hypercapnia increased phrenic nerve activity as well as the activity of the two cranial nerves. While linear increases occurred in phrenic and recurrent laryngeal nerve activity with both chemical stimuli, the relationship between hypoglossal and phrenic nerve activity was curvilinear. At lower levels of chemical drive, changes in hypoglossal nerve were less than in the phrenic, and the reverse was true at higher levels of chemical stimulation. There were also differences in the response of both cranial nerves and the phrenic to changing vagal stimulation. The dissimilarities observed in the cranial response of the nerves (versus the phrenic) could potentially affect the forces developed during inspiration and lead to obstruction in the upper airway.

Pharmacokinetic linearity of desipramine hydrochloride

The pharmacokinetic linearity of two single oral doses of desipramine hydrochloride was examined in a parallel study involving 30 subjects. Fourteen subjects received 75 mg (3 x 25 mg) of desipramine hydrochloride, and 16 subjects received 150 mg (1 x 150 mg). An open one-compartment model with a lag time to the start of absorption was used to examine the pharmacokinetic linearity. The results of the study suggest that the kinetics are linear in the dose range studied.

Diagnostic quantification of CASS (coronary artery surgery study) clinical and exercise test results in determining presence and extent of coronary artery disease. A multivariate approach

Multivariate linear discriminant function analysis on maximal exercise treadmill and angiographic data from 500 men with definite angina, 584 men with probable angina and 267 men with nonspecific chest pain identified independent predictors of presence and extent of coronary disease. We used the discriminant function to develop a clinical risk index and a clinical and exercise risk index for each patient subset. Probability curves were generated to predict the presence and extent of coronary disease. In definite angina cases, exercise testing provided more diagnostic information than clinical data alone. However, in the 10% of cases with the smallest risk indexes, half of the patients had coronary disease and one-quarter had multivessel disease. In men with probable angina, exercise testing added substantially more diagnostic information than clinical data. The probability of multivessel disease was reduced to less than 10% for 30% of patients with probable angina, an important diagnostic contribution. Exercise testing in men with nonspecific chest pain was of limited value because disease prevalence was already low.

Estimating pA2 values for different designs

The method for analyzing data leading to the estimation of a pA2 depends on the experimental design. Three different experimental designs are discussed. For each design, we provide a brief description of experimental situations that give rise to the design, a means for verifying relevant assumptions, and sample data with summary calculations.

Requests for abortion and outcomes of pregnancy in Jerusalem, Israel

Outcomes of pregnancy were examined for 480 women who requested abortions at a Jerusalem hospital during the years 1972 to 1975. Of 149 women denied abortions, 80 apparently obtained illegal ones. Since illegal abortions performed by physicians are easily and safely obtained in Israel, the liberalization of Israel's abortion laws will not have a major impact upon Israel's population growth.

Radical one-stage posteromedial release for the resistant clubfoot

A large proportion of congenital talipes equinovarus is resistant to correction by nonoperative means. The authors reviewed 54 feet which required surgical intervention, and the operative management utilized was a radical one-stage posteromedial release. Application of plastic surgical techniques has obviated problems of skin healing. Comparable to results reported by others, a good-to-excellent functional and cosmetic result can be expected in 90% of the cases. Careful attention to a well-designed postoperative regimen will frequently obviate the need for additional surgery.

The Fabella Syndrome

The Fabella Syndrome is recognized by a sharp pain, local tenderness, and intensification of pain in the area of the fabella by full extension of the knee. After diagnostic tests with local anesthesia and ineffective conservative treatment, surgical extirpation may produce lasting relief of symptoms.