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Biomedical subjects

J M Goodman

Publications and source records attributed to J M Goodman.

At least 19 recordsLinked to original sources
PubMed1992

Ligand atom partial charges assignment for complementary electrostatic potentials.

The design of molecules to fit into the active site of receptors is a rapidly developing area of pharmacology and medicinal chemistry. A good ligand needs a suitable geometry and also appropriate electrostatic properties. The electrostatic properties of the ligand should complement those of the receptor. We present a method for the assignment of atom-centred point charges for a ligand, based on the electrostatic potential of the receptor. These point charges are chosen to give the best possible complementarity to the receptor electrostatic potential over the van der Waals surface of the ligand. We demonstrate that point charges can be chosen to give good electrostatic complementarity, and suggest that a molecule with similar electrostatic properties should bind well to the receptor.

Binding Sites↗
PubMed1992

Development of multipurpose peroxisomes in Candida boidinii grown in oleic acid-methanol limited continuous cultures.

We have studied the development and metabolic significance of peroxisomes in the yeast Candida boidinii following adaptation of the organism to cultivation conditions which require the simultaneous presence and activity of two independent peroxisome-mediated pathways for growth. After the addition of methanol to oleic acid-grown cells at late exponentional growth, a number of new small peroxisomes developed which, apart from the presence of beta-oxidation enzymes, were characterized by the presence of enzymes involved in methanol metabolism (alcohol oxidase and dihydroxyacetone synthase). The latter proteins, however, were absent in the larger organelles which were originally present in the oleic acid-grown cells prior to the addition of methanol and which contained only enzymes of the beta-oxidation pathway. Subsequent experiments on cells from continuous cultures grown on a mixture of oleic acid and methanol at steady-state conditions revealed that both the enzymes of the beta-oxidation pathway and those involved in methanol metabolism were found in one and the same compartment. Thus, under these conditions the cells contained peroxisomes which were concurrently involved in the metabolism of two different carbon sources simultaneously used for growth. Our results indicated that the heterogeneity in the peroxisomal population of a single cell, observed in the transient state following the addition of methanol, is only temporary and due to heterogeneity among these organelles with respect to their capacity to incorporate newly synthesized matrix proteins.

Acetyl-CoA C-Acetyltransferase↗
PubMed1992

Aerobic fitness and hormonal responses to prolonged sleep deprivation and sustained mental work.

This study examined the influence of aerobic fitness on the responses of selected hormones to the combined stressors of sleep deprivation (SD) and sustained mental work. Six aerobically high fit (HF) (VO2max greater than 50 ml.kg-1.min-1) and six average fit (AF) (VO2max less than 40 ml.kg-1.min-1) female subjects were subjected to a period of sleep loss of 60 h during which time they performed sustained mental tasks with no physical activity component. Venous blood samples were drawn every 12 h at 1330 hours and 0130 hours and plasmas analyzed for cortisol, growth hormone (hGH), prolactin, thyroxine (T4), triiodothyronine (T3), and reverse-triiodothyronine (rT3). For cortisol, both the HF and AF groups exhibited the normal high-daytime and low-nighttime pattern of secretion, with levels increasing significantly as the duration of SD increased. The normal elevations of hGH and prolactin levels during normal sleep were suppressed during SD. No significant fitness effects were found for cortisol, hGH, and prolactin responses. Plasma levels of T4, T3, and rT3 increased significantly during SD, with highly fit subjects exhibiting higher levels of these hormones than those of average fitness. We suggest that aerobic fitness may influence the peripheral metabolism of T4 during SD, but that aerobic fitness does not influence the regulation of the classical stress hormones during SD.

Adult↗
PubMed1992

Impaired cardiopulmonary response to exercise in moderate hypertension.

OBJECTIVE: To identify the limiting factors of exercise performance in subjects with hypertension associated with left ventricular hypertrophy. The secondary objective was to establish relationship between peripheral function and exercise capacity. DESIGN: Cardiopulmonary exercise testing was conducted using two protocols: a graded exercise test to maximal effort established maximal exercise capacity, followed by a step-incremental test combining gas-exchange measures and radionuclide angiography. The exercise responses were compared within and between groups. SETTING: All hypertensive subjects were selected from the Toronto Tri-Hospital Hypertension Clinic. Normal subjects were recruited from the surrounding community. PATIENTS: Twelve patients with established hypertension and left ventricular hypertrophy (determined by echocardiography) were studied as a referred/volunteer sample. All had no evidence of coincident diseases and were unmedicated at time of testing. A volunteer sample of normal, healthy subjects acted as a control. INTERVENTIONS: Graded exercise to maximum and step-incremental (submaximal and steady-state) exercise was used to quantify cardiopulmonary function during exercise stress. MAIN OUTCOME MEASURES: These included (for exercise performance) maximal oxygen intake (VO2max), the ventilatory anaerobic threshold, total peripheral resistance and blood lactate. Cardiac function measures included ejection fraction and ventricular volumes. RESULTS: Cardiac function data obtained during exercise in hypertensive subjects included an increase in the pressure to volume ratio, but a blunted ejection fraction response at peak exercise (P less than 0.05). Although end-diastolic volume increased during exercise (P less than 0.05), values were lower during both levels of exercise compared with normal subjects. Mean +/- SD end-systolic volume increased from 39 +/- 22 at rest to 42 +/- 23 mL during peak exercise. Hypertensive subjects had a lower VO2 max (mean 27.4 +/- 4.8 mL/kg/min) compared with normals (40.0 +/- 8.5 mL/kg/min) and a lower ventilatory anaerobic threshold (14.4 +/- 2.9 versus 27.6 +/- 5.8 mL/kg/min, P less than 0.005). Furthermore, hypertensive patients had a significantly elevated total peripheral resistance at rest (2.5 +/- 1.0 versus 1.8 +/- 0.4 peripheral resistance units) and at peak exercise (1.6 +/- 0.7 versus 0.8 +/- 0.2, P less than 0.01) compared with normal subjects (P less than 0.05). A correlation coefficient of 0.92 was found between total peripheral resistance and VO2 max in hypertensive subjects (P less than 0.01). CONCLUSIONS: These data suggest that peripheral factors, specifically a failure to reduce significantly total peripheral resistance, limits exercise performance despite a maintenance of left ventricular function during exercise in patients with moderate hypertension. The use of cardiopulmonary exercise testing can help in identifying the underlying cause of exercise intolerance in this population and limited left ventricular reserve at peak exercise, and may offer a sensitive measure of therapeutic end-points.

Adult↗
PubMed1991

The hard tissue lesion revisited.

Recent research indicates that the thorough removal of calculus is still a critical step in the treatment of periodontal disease. Surgical access facilitates this in deep pockets. Repair is mediated by a long junctional epithelium as microscopically total calculus removal is rarely achieved. In intrabony defects the apical portion of the root surface which has not attracted deposits of calculus has the potential for connective tissue reattachment and regeneration if care is taken to preserve collagen fibres still attached to the root.

Dental Deposits↗
PubMed1991

Left ventricular functional response to moderate and intense exercise.

The left ventricular (LV) volume and ejection fraction (EF) response to upright exercise was assessed on 15 normal subjects during cycle ergometry. Measures of cardiac function and gas exchange were made at rest, at 85% of the ventilatory anaerobic threshold (VAT; WL1), and at peak exercise (WL2). EF increased from rest (58 +/- 12%) during WL1 (66 +/- 10%), reaching significantly higher values at WL2 (69 +/- 8%; p less than .05). End-diastolic volume increased from rest during WL1 (136 +/- 36 ml vs. 118 +/- 32 ml; p less than .05), becoming significantly higher than rest during WL2 (141 +/- 41 ml). End-systolic volume was unchanged from rest (51 +/- 25 ml) during submaximal exercise (50 +/- 20 ml), but it decreased significantly during WL2 (44 +/- 21 ml; p less than .05). The systolic pressure/end-systolic volume ratio increased from 3.0 +/- 1.7 (rest) to 5.8 +/- 3.0 at WL2 (p less than .05). These results suggest that the Frank-Starling mechanism is operative throughout exercise, particularly during exercise below the VAT. LV performance after the VAT is further augmented by increased contractility with continued, yet diminished, utilization of the Frank-Starling mechanism.

Adult↗
PubMed1990

Sorting of peroxisomal membrane protein PMP47 from Candida boidinii into peroxisomal membranes of Saccharomyces cerevisiae.

A gene encoding PMP47, a peroxisomal integral membrane protein of the methylotrophic yeast Candida boidinii, was isolated from a genomic library. DNA sequencing of PMP47 revealed an open reading frame of 1269 base pairs capable of encoding a protein of 46,873 Da. At least two membrane-spanning regions in the protein are predicted from the sequence. Since the 3 amino acids at the carboxyl terminus are -AKE, PMP47 lacks a typical peroxisomal sorting signal. No significant similarities in primary structure between PMP47 and known proteins were observed, including PMP70, a rat peroxisomal membrane protein whose sequence has recently been reported (Kamijo, K., Taketani, S., Yokota, S., Osumi, T., and Hashimoto, T. (1990). J. Biol. Chem. 265, 4534-4540). In order to study the import and assembly of PMP47 into peroxisomes by genetic approaches, the gene was expressed in the yeast Saccharomyces cerevisiae. When PMP47 was expressed in cells grown on oleic acid to induce peroxisomes, the protein was observed exclusively in peroxisomes as determined by marker enzyme analysis of organelle fractions. Most of the PMP47 co-purified with the endogenous peroxisomal membrane proteins on isopycnic sucrose gradients. Either in the native host or when expressed in S. cerevisiae, PMP47 was not extractable from peroxisomal membranes by sodium carbonate at pH 11, indicating an integral membrane association. These results indicate that PMP47 is competent for sorting to and assembling into peroxisomal membranes in S. cerevisiae.

Amino Acid Sequence↗
PubMed1990

Immunocytochemical evidence for the acidic nature of peroxisomes in methylotrophic yeasts.

The possible acidic nature of the peroxisomal matrix present in intact yeast cells was studied immunocytochemically, using the weak base DAMP as a probe. Spheroplasts of methanol-grown Candida boidinii and Hansenula polymorpha were regenerated and incubated with DAMP. After immunogold labelling, using antibodies against DAMP, a specific accumulation of gold particles was observed on the peroxisomal profiles. This labelling was absent in controls, performed in the presence of ionophores or chloroquine. These results support earlier observations, that in intact cells a pH-gradient exists across the peroxisomal membrane. Experiments, carried out on osmotically swollen spheroplasts indicated that maintenance of this pH-gradient is strongly related to the cell's integrity.

Candida↗
PubMed1990

Peroxisomal protein import is conserved between yeast, plants, insects and mammals.

We have previously demonstrated that firefly luciferase can be imported into peroxisomes of both insect and mammalian cells. To determine whether the process of protein transport into the peroxisome is functionally similar in more widely divergent eukaryotes, the cDNA encoding firefly luciferase was expressed in both yeast and plant cells. Luciferase was translocated into peroxisomes in each type of organism. Experiments were also performed to determine whether a yeast peroxisomal protein could be transported to peroxisomes in mammalian cells. We observed that a C-terminal segment of the yeast (Candida boidinii) peroxisomal protein PMP20 could act as a peroxisomal targeting signal in mammalian cells. These results suggest that at least one mechanism of protein translocation into peroxisomes has been conserved throughout eukaryotic evolution.

Animals↗
PubMed1990

Proliferation and metabolic significance of peroxisomes in Candida boidinii during growth on D-alanine or oleic acid as the sole carbon source.

We have studied the induction of peroxisomes in the methylotrophic yeast Candida boidinii by D-alanine and oleic acid. The organism was able to utilize each of these compounds as the sole carbon source and grew with growth rates of mu = 0.20 h-1 (on D-alanine) or mu = 0.43 h-1 (on oleic acid). Growth was associated with the development of many peroxisomes in the cells. On D-alanine a cluster of tightly interwoven organelles was observed which made up 6.3% of the cytoplasmic volume and were characterized by the presence of D-amino acid oxidase and catalase. On oleic acid rounded to elongated peroxisomes were dominant which were scattered throughout the cytoplasm. These organelles contained increased levels of beta-oxidation enzymes; their relative volume fraction amounted 12.8% of the cytoplasmic volume.

Alanine↗
PubMed1990

Association of glyoxylate and beta-oxidation enzymes with peroxisomes of Saccharomyces cerevisiae.

Although peroxisomes are difficult to identify in Saccharomyces cerevisiae under ordinary growth conditions, they proliferate when cells are cultured on oleic acid. We used this finding to study the protein composition of these organelles in detail. Peroxisomes from oleic acid-grown cells were purified on a discontinuous sucrose gradient; they migrated to the 46 to 50% (wt/wt) sucrose interface. The peroxisomal fraction was identified morphologically and by the presence of all of the enzymes of the peroxisomal beta-oxidation pathway. These organelles also contained a significant but minor fraction of two enzymes of the glyoxylate pathway, malate synthase and malate dehydrogenase-2. The localization of malate synthase in peroxisomes was confirmed by immunoelectron microscopy. It is postulated that glyoxylate pathway enzymes are readily and preferentially released from peroxisomes upon cell lysis, accounting for their incomplete recovery from isolated organelles. Small uninduced peroxisomes from glycerol-grown cultures were detected on sucrose gradients by marker enzymes. Under these conditions, catalase, acyl-coenzyme A oxidase, and malate synthase cofractionated at equilibrium close to the mitochondrial peak, indicating smaller, less dense organelles than those from cells grown on oleic acid. Peroxisomal membranes from oleate cultures were purified by buoyant density centrifugation. Three abundant proteins of 24, 31, and 32 kilodaltons were observed.

Centrifugation, Zonal↗
PubMed1990

Peroxisomal assembly: membrane proliferation precedes the induction of the abundant matrix proteins in the methylotrophic yeast Candida boidinii.

Peroxisomes are massively induced when methylotrophic yeasts are cultured in medium containing methanol. These organelles contain enzymes that catalyze the initial steps of methanol assimilation. In Candida boidinii, a methylotrophic yeast, the peroxisomal matrix (internal compartment) is composed almost exclusively of two proteins, alcohol oxidase and dihydroxyacetone synthase; catalase is present in much lower abundance. Monoclonal and polyclonal antibodies are available against peroxisomal matrix and membrane proteins. These were utilized to correlate the induction of specific proteins with the morphological changes occurring during peroxisomal proliferation. Cells cultured in glucose-containing medium contain two to five small microbodies, which are identifiable by catalase staining and immunoreactivity with a monoclonal antibody against PMP47, an integral peroxisomal membrane protein. Three stages of proliferation can be distinguished when cells are switched to methanol as the carbon source. (1) There is an early stage (within 1 h) in which several peroxisomes develop from a preexisting organelle. This is accompanied by an increase in catalase activity and an induction of PMP47, but no detectable induction of alcohol oxidase or dihydroxyacetone synthase is observed. (2) From 1 to 2.5 h there is further division of these microbodies until up to 30 small peroxisomes generally are present in each of one or two clusters per cell. Induction of alcohol oxidase, dihydroxyacetone synthase and PMP20, a protein that is distributed in the matrix and membrane, is detectable during this time. Serial sections reveal that some peroxisomes remain uninduced while others undergo proliferation. Such sections also show no obvious connections between peroxisomes within clusters.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Oxidoreductases↗
PubMed1990

Peroxisomes induced in Candida boidinii by methanol, oleic acid and D-alanine vary in metabolic function but share common integral membrane proteins.

Peroxisomes massively proliferate in the methylotrophic yeast Candida boidinii when cultured on methanol as the only carbon and energy source. These organelles contain enzymes that catalyze the initial reactions of methanol utilization. The membranes contain abundant proteins of unknown function; their apparent molecular masses are 20, 31, 32 and 47 x 10(3) Mr and are termed PMP20, PMPs31-32 and PMP47. Recently, we reported that peroxisomes in this yeast are also induced by oleic acid and D-alanine as carbon sources, and that these peroxisomes contain increased concentrations of the enzymes of fatty acid beta-oxidation or D-amino acid oxidase, respectively. This report extends these findings and further compares the enzyme composition from peroxisomes induced by methanol, oleic acid and D-alanine. the patterns of matrix proteins represented on SDS-polyacrylamide gels from peroxisomes induced by oleic acid or D-alanine were found to be very different from those of peroxisomes induced by methanol. In order to differentiate between membrane proteins that have specific functions in pathways of substrate utilization from those with more generalized functions, peroxisomal membranes from cultures grown on methanol, oleic acid or D-alanine were purified. Analysis of these fractions demonstrated that while PMP20 is found only in peroxisomes induced by methanol, the PMPs31-32 and PMP47 were the abundant peroxisomal membrane proteins (PMP) regardless of inducing substrate. The data strongly suggest that the function of PMP20 is related to methanol metabolism. In contrast, the functions of PMPs31-32 and PMP47 are 'substrate-nonspecific'. We speculate that they may relate to the structure, assembly or general function of the organelle.

Alanine↗
PubMed1990

Moderate exercise and hemodilution during sleep deprivation.

The effect of 52 h of sleep deprivation (SD) upon blood constituents was studied in 12 young women aged 21.5 +/- 0.4 years. Subjects were individually isolated without time cues, performing a sequence of cognitive tasks. Significant decreases in hematocrit (p less than 0.002) and red cell count (p less than 0.04) developed, mainly over the first 28 h of SD, reaching a subsequent plateau or partial recovery. The calculated plasma volume also increased by 10.7 +/- 3.1% at 52 h, with recovery to a 6.9 +/- 3.2% increase the following day. About 1 L of water was retained over the first 30 h of SD, with a subsequent partial elimination of this excess. Plasma albumin and total protein concentrations were largely sustained in the face of the plasma expansion. The plasma pH showed a progressive fall from a baseline value of 7.381 +/- 0.014 to 7.332 +/- 0.006 at 52 h, while plasma bicarbonate decreased from a baseline figure of 31.2 +/- 0.7 to 26-27 mM/L (p less than 0.05). After 8 weeks, all subjects repeated the experiment, with the introduction of 30 min of exercise in the 40th h of wakefulness. Hematocrit and plasma volume changes were similar to those of the first experiment up to the time of exercise, but hematocrit decreased and plasma volume increased after the exercise bout, rather than reaching a plateau. Plasma pH increased with exercise, but returned to the previous low level at 52 h. Any arousing effect of the exercise bout was transient. The plasma expansion reflects metabolic and/or respiratory acidosis, plus possible effects of a prolonged period without recumbency.

Adult↗
PubMed1989

Two genes encode the major membrane-associated protein of methanol-induced peroxisomes from Candida boidinii.

A massive proliferation of peroxisomes occurs in the yeast Candida boidinii when methanol is utilized as the sole carbon source; these peroxisomes contain the enzymes which catalyze the initial steps of methanol utilization. The most abundant peroxisomal membrane-associated protein has an apparent molecular mass of 20 kDa and is termed PMP20. We report the isolation of two genes that encode very similar forms of PMP20; this is the first report of genes that encode proteins associated with peroxisomal membranes. Southern analysis demonstrates that the two genes are on different loci, although there are several homologous regions of both 5'- and 3'-untranslated sequence. One of the areas of 5' homology is within the untranslated region of the mRNA. Within the coding region there are 35 base differences between the two genes that are reflected in only five amino acid differences. The mRNAs representing both genes of PMP20 are induced in cells grown in methanol-containing medium and are below detection in cells grown in glucose. S1 nuclease protection analysis indicates that there is a 2.5-fold difference in mRNA expression between the two genes when induced. The predicted sequences of both PMP20 genes show the absence of a cleaved amino-terminal leader sequence and the presence of only 1 cysteine residue. In agreement with previous biochemical data suggesting a peripheral association of this protein with the membrane (Goodman, J. M., Maher, J., Silver, P. A., Pacifico, A., and Sanders, D. (1986) J. Biol. Chem. 261, 3464-3468), there are no obvious membrane spanning regions predicted in the sequences. Both PMP20 gene products contain the carboxyl-terminal sequence AKL, similar to the putative SKL peroxisomal sorting sequence (Gould, S. J., Keller, G.-A., and Subramani, S. (1988) J. Cell Biol. 107, 897-905).

Amino Acid Sequence↗
PubMed1988

Outcome of self-inflicted gunshot wounds of the brain.

A consecutive series of 67 patients who had sustained self-inflicted gunshot wounds of the brain was reviewed retrospectively to evaluate factors determining outcome. Weapon caliber, site of bullet entry, degree of brain wounding on computerized tomographic scan, and presenting Glasgow Coma Scale (GCS) score were examined. Overall mortality, degree of disability in survivors, and survival time after injury in fatally wounded patients were assessed. Ninety-eight percent of all patients with an initial GCS score of 8 or less died. When the GCS score was more than 8, 91% of patients survived (P less than .0001). Survival rate was significantly increased in patients with injury limited to one lobe of the brain, compared with patients with brain wounds of greater severity demonstrated on computerized tomographic scan (P less than .05), while a missile crossing both vertical anatomic planes of the brain or coming to rest in the posterior fossa was lethal in 100% of cases. Survivors scored relatively well on the Glasgow Outcome Scale. Almost all (98%) fatally injured patients maintained vital functions for a time ample for transportation and evaluation at a major referral center. These findings hold important implications for trauma center and critical care resource allocation as well as organ transplantation programs.

Adolescent↗
PubMed1987

Proton ionophores prevent assembly of a peroxisomal protein.

Peroxisomal matrix proteins are imported into the organelle posttranslationally. Here we report that proton ionophores disrupt the import and assembly of alcohol oxidase, a homo-octameric flavoprotein of the induced peroxisome from the methylotrophic yeast Candida boidinii. When drug is added to cells containing newly synthesized monomeric alcohol oxidase, octamerization fails to occur and a membrane-associated complex is formed instead. The formation of the complex, which appears to face the cytoplasmic side of the membrane, is reversed when drug is removed, leading to the generation of octamer. Surprisingly, when drug is added to cells containing newly assembled octamers, they dissociate into monomers. We suggest that both the complex and the labile octamer are intermediates in the normal assembly pathway of alcohol oxidase and that energy is required for import and maturation of this peroxisomal protein.

Alcohol Oxidoreductases↗