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Biomedical subjects

J Greenberg

Publications and source records attributed to J Greenberg.

At least 145 records · Page 8Linked to original sources
PubMed1987

Detection of endogenous ethanol and other compounds in the breath by gas chromatography with on-column concentration of sample.

A new method is described for collecting and concentrating volatile compounds in the breath, in order to facilitate their assay by gas chromatography. Breath was collected into sealed Mylar bags containing an internal standard (isopropyl alcohol). The sample was pumped through a cooled gas chromatograph column, where the volatile compounds were concentrated by adsorption onto the resin packing (Porapak Q) at 35 degrees C. The column was then heated, and the volatilized sample was separated for assay by flame ionization detection. The assay was highly sensitive for ethanol (detecting at least 4.0 nmol) and linear up to 20 nmol (r2 = 0.98). Accuracy and precision were determined by assaying nine replicates of a sample containing 12.0 nmol ethanol; a mean value of 12.18 nmol ethanol was obtained with a coefficient of variation of 10.26%. In a group of normal volunteers, endogenous breath ethanol concentrations ranged from 2.23 to 6.51 nmol/liter. This assay provided a number of advantages over previously described methods: The use of breath collection bags enabled the collection of samples outside the laboratory. The use of an internal standard in the collection bag reduced errors that might have resulted from leakage of the specimen. An on-column concentration of the sample in the gas chromatograph eliminated the need for an additional preconcentration device, such as a cryogenic or adsorptive trapping apparatus.

Breath Tests↗
PubMed1987

Regional cerebral glucose metabolism in aphemia: a case report.

Local cerebral metabolism was determined in a patient suffering aphemia following cerebral infarction using the 18FDG-PET technique. The syndrome was characterized by profound ictal nonfluency with sparing of other language functions. Speech subsequently improved so that content and grammar were appropriate but mild dysprosody persisted. Conventional CT showed no lesion of the left hemisphere while PET revealed a discrete focus of hypometabolism on the left which partially resolved on serial studies. The metabolic lesion could be localized to the region of the inferior precentral gyrus and the adjacent subcortical space.

Aged↗
PubMed1987

Structural responsiveness of filamentous bacteriophage Pf1: comparison of virion structure in fibers and solution. The effect of temperature and ionic strength.

X-ray diffraction from fibers and magnetically oriented solutions has been used to study the effect of changes in environment on the helical symmetry and radial structure of the Pf1 virus particle. Detailed analysis of equatorial scattering to a spacing of 8-10 A was used to identify small radial motions of structural elements in the virus particle. R-factor ratios were used to determine the statistical significance of observed changes. Comparison of the structure of virus particles in fibers with those in solution indicated that the helical symmetry of the virions remains unchanged during fiber formation. In most fibers the virions appear to be slightly distorted by the tight packing of virus particles. This distortion results in an apparent increase in the radius of the virus particle of approximately 0.6 A. A change in the radius of the DNA is also observed. Increase in the concentration of solvent molecules during fiber formation results in penetration of the virus interior by some solvent components. NaCl is also able to enter the virus interior. The change in the helical symmetry of the virions at approximately 8 degrees C appears to be the same whether observed by diffraction from fibers or from solutions. Only subtle changes in radial structure are associated with the temperature transition.

Coliphages↗
PubMed1987

Depression, self-focused attention, and expectancies for positive and negative future life events for self and others.

In two studies, we examined depressed and nondepressed persons' judgments of the probability of future positive and negative life events occurring to themselves and to others. Study 1 demonstrated that depressed subjects were generally less optimistic than their nondepressed counterparts: Although nondepressed subjects rated positive events as more likely to happen to themselves than negative events, depressed subjects did not. In addition, relative to nondepressed subjects, depressed subjects rated positive events as less likely to occur to themselves and more likely to occur to others and negative events as more likely to occur to both self and others. Study 2 investigated the role that differential levels of self-focused attention might play in mediating these differences. On the basis of prior findings that depressed persons generally engage in higher levels of self-focus than nondepressed persons do and the notion that self-focus activates one's self-schema, we hypothesized that inducing depressed subjects to focus externally would attenuate their pessimistic tendencies. Data from Study 2 supported the hypothesis that high levels of self-focus partially mediate depressive pessimism: Whereas self-focused depressed subjects were more pessimistic than nondepressed subjects, externally focused depressed subjects were not. The role of attentional focus in maintaining these and other depressive pessimistic tendencies was discussed.

Adult↗
PubMed1987

Hangman's fracture: radiologic assessment in 27 cases.

Traumatic spondylolisthesis of C-2, frequently referred to as the hangman's fracture, is typically regarded as a hyperextension injury with rare neurologic sequelae by virtue of decompression of the neural canal. The authors retrospectively evaluated their radiographic experience with this injury in 27 patients over a 24-month period. Lateral cervical spine studies and computed tomography (CT) scans (21 patients) were analyzed. CT studies provided better delineation of the fracture in all 21 patients and significant additional information in five patients (24%). Seven patients (26%) suffered initial neurologic sequelae in association with the C-2 injury. Nine patients had additional sites of fracture, including seven with associated C-1 ring disruption (26%). Extension of the fracture line into the transverse vertebral artery foramen led to vertebral artery injury and cerebellar embolization in one patient. Angiography may be necessary to detect intimal injury to the vertebral arteries when the fracture extends through the transverse foramina and to indicate the need for anticoagulation when clinically feasible.

Adolescent↗
PubMed1987

Modulation of the effects of alveolar macrophages on lung fibroblast collagen production rate.

Alveolar macrophages (AM) may function as effector cells that can either stimulate or inhibit lung fibroblast collagen production. However, conditions that determine the predominant effect of AM on fibroblasts are not well understood. To delineate factors that modulate the effects of AM on lung fibroblasts, we studied the interaction of AM products and fibroblasts in vitro. The AM were obtained by bronchoalveolar lavage of hamsters with bleomycin-induced pulmonary fibrosis. Conditioned medium (CM) from the AM cultures was incubated in varying amounts with lung fibroblast (IMR-90) cultures. After metabolic labeling with [3H]proline, fibroblast collagen production based on procollagen-specific radioactivity was determined (Anal Biochem 1984; 140:478). Macrophage CM in concentrations greater than 5% suppressed collagen production, an event attributed to the macrophage-derived suppressive factor that we have previously characterized (J Clin Invest 1983; 72:2082). Macrophages were also determined to produce PGE2 in culture (500 pg/10(6) cells). Authentic PGE2 at concentrations found in CM was found to suppress fibroblast collagen production, indicating that AM-derived PGE2 contributes to the suppressive activity in CM. To examine possible stimulatory factors in CM, the fibroblasts were preincubated with indomethacin. This approach was based on our previous observation that AM-derived suppressive factor increases endogenous fibroblast PGE2 and that its activity can be blocked by indomethacin. Macrophage CM in a concentration of 20% did not suppress the collagen production of indomethacin-treated fibroblasts. However, CM concentrations of 5 and 10% increased collagen production (173 and 143% of control values, respectively), indicating the presence of stimulatory factor(s) in macrophage-conditioned medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Metabolic and clinical correlates of acute ischemic infarction.

We studied cerebral metabolism, anatomy, and clinical status in 36 patients with acute cerebral ischemia. Results from FDG-PET were compared with CT to find the relationships between the metabolic, anatomic, and clinical findings. Metabolic abnormalities seen on PET frequently were more extensive than the corresponding CT findings. The pattern of metabolic abnormality was significantly related to both the type of clinical syndrome and the degree of eventual recovery. No such relationships were found for the CT results. We conclude that studies of cerebral metabolism are of value in establishing prognosis after acute cerebral ischemia. Also, knowledge of the patterns of cerebral dysmetabolism provides a powerful means for the localization of clinical function.

Aged↗
PubMed1987

Quantitative autoradiography of parathyroid glands in rats with carbon-14-labeled amino acids.

We have utilized a quantitative autoradiographic method as a means of evaluating amino acid uptake of the rat parathyroid gland for the ultimate purpose of finding agents potentially suitable for position emission tomographic scanning of parathyroid glands. L-[1-14C]leucine and L-[guanido-14C]arginine were evaluated because of their relatively high content in the synthetic products of the parathyroid glands compared with other neck tissues, thyroid gland, and muscle. Carbon-14 leucine disappeared rapidly from plasma following intravenous injection and there was relatively selective uptake of the [14C]leucine and [14C]arginine by the parathyroid glands when compared with uptake by the thyroid gland and neck muscle. These data suggest that both agents warrant further investigation for their potential utility in positron emission tomographic scanning of the parathyroid gland.

Amino Acids↗
PubMed1986

Persistent high self-focus after failure and low self-focus after success: the depressive self-focusing style.

Two studies were conducted to assess the spontaneous self-focusing tendencies of depressed and nondepressed individuals after success and failure. Based on a self-regulatory perseveration theory of depression, it was expected that depressed individuals would be especially high in self-focus after failure and low in self-focus after success. The results of Experiment 1 suggested that immediately after an outcome, both depressed and nondepressed individuals are more self-focused after failure than after success. This finding led us to hypothesize that differences between depressed and nondepressed individuals in self-focus following success and failure emerge over time. Specifically, immediately following an outcome, both types of individuals self-focus more after failure because of self-regulatory concerns. However, over time, depressed individuals persist in higher levels of self-focus after failure than after success, whereas nondepressed individuals shift to the opposite, more hedonically beneficial pattern. The results of Experiment 2 provided clear support for these hypotheses. Theoretical implications of these results were discussed.

Adolescent↗
PubMed1986

Proteolysis of platelet glycoprotein Ib by plasmin is facilitated by plasmin lysine-binding regions.

We have characterized the effects of plasmin on glycoprotein Ib (GpIb), a platelet membrane receptor for von Willebrand factor (vWF), and on glycocalicin, a fragment of the alpha chain of GpIb that contains the vWF-binding region. The addition of 4.5 X 10(-7) mol/L plasmin to washed platelets caused a time-dependent decrease in ristocetin-induced, vWF-dependent platelet agglutination. epsilon-Aminocaproic acid (EACA) inhibited plasmin release of glycocalicin-related antigen from washed platelets and preserved vWF-dependent platelet agglutination, thus indicating that the lysine-binding sites on plasmin facilitated its degradation of GpIb. To demonstrate a direct interaction between plasmin and the vWF-binding region of GpIb we incubated purified glycocalicin with plasmin. Plasmin degraded the glycocalicin into two small carbohydrate-poor peptides and into a larger carbohydrate-rich fragment. EACA was able to inhibit plasmin-mediated degradation of glycocalicin in a concentration-dependent fashion. These studies indicated that plasmin degradation of GpIb was due to a direct interaction between plasmin and GpIb and that this effect was mediated by the lysine-binding region of the plasmin molecule.

Aminocaproates↗
PubMed1985

Cerebral infarction in sickle cell trait.

Sickle cell disease is known to predispose patients to the risk of cerebral infarction. However, only scattered reports exist of the neurological sequelae of the sickle cell trait. Only 8 cases are reported in the English literature, in some of which the sickle cell trait was not documented by hemoglobin electrophoresis. This report describes 2 men, age 35 and 24 years, who developed acute cerebral infarction. Investigation revealed no apparent cause for the lesion other than the sickle cell trait.

Adult↗
PubMed1985

Studies of the guinea-pig epididymis. III. Innervation of epididymal segments.

The innervation of the ductuli efferentes and seven zones of the guinea-pig epididymis was investigated using immunohistochemical, histochemical and electron-microscopical techniques. Nerve fibers were localized by use of antibodies against substance P (SP-IR), vasoactive intestinal polypeptide (VIP-IR) and dopamine-beta-hydroxylase (DBH-IR). In the ductuli efferentes and all zones of the epididymal duct, SP-IR is consistently observed in the interstitial tissue and perivascular areas. Histochemistry reveals a significant amount of acetylcholinesterase-containing fibers in the interstitial, perivascular and periductal smooth muscles of the ductuli efferentes and zones V, VI and VII. In contrast to the homogeneous distribution of SP-IR within all zones of the epididymis, VIP-IR is seen only in zones VI and VII. Within these zones, VIP-IR is detected in large amounts in the subepithelial and muscular layers as is a sparse number of SP-IR varicosities. DBH-IR is also seen throughout all zones in the interstitial and perivascular regions with a tendency to increase in zones VI and VII. Transmission electron microscopy (TEM) reveals evidence of a cholinergic (agranular vesicles, AGV), adrenergic (small granular vesicles, SGV) and peptidergic (large granular vesicles, LGV) innervation throughout the interstitial connective tissue of the ductuli efferentes and all epididymal zones. Furthermore AGV are localized in the subepithelial layer, and also co-stored with LGV in the muscular layer of zones VI and VII. No nerve profiles were encountered within the epithelium. A correlation of immunohistochemical findings to TEM counterparts as well as their possible functional role are discussed.

Animals↗
PubMed1985

Morphology and innervation of a testicular 'rete mirabile' in the guinea-pig.

The morphology and innervation of the testicular artery and pampiniform plexus of the guinea-pig was investigated using light immunohistochemistry as well as transmission and scanning electron microscopy. The tortuous, spiraled testicular artery embedded within the epididymal fat pad is totally encompassed by a thin-walled sinus-like labyrinthine structure comprising the pampiniform plexus. Characteristic features of this lacunar system are: 1. Endothelial bridges, strands or trabeculae of various length, width and thickness which project into the lumen, occasionally branch, and attach to the opposite or adjacent area of the venous wall. 2. A frequent discontinuous smooth muscular layer. Nerve fibers were localized by use of antibodies against dopamine-beta-hydroxylase (DBH-IR), neuropeptide Y (NPY-IR), and substance P (SP-IR). A great abundance of NPY-IR and DBH-IR axon bundles are seen surrounding the testicular artery. Fibers emanating from this dense plexus travel into the interstitium to finally innervate the walls of the sinus-like system, including the cross-luminal trabeculae. In contrast, larger varicosities are distinctive for SP-IR fibers which are also located at the media-adventitia border of the arterial and venous walls but to a far lesser extent than that seen with DBH-IR or NPY-IR. The axon varicosities supplying the arterial and venous walls contain a heterogeneous population of various types of vesicles, mostly including small agranular and granular ones as well as large granular vesicles of various size and density. The most conspicuous feature concerning the innervation pattern of the venous wall is the occurrence of numerous neuroendothelial contact zones. The findings of the investigated 'rete mirabile' are discussed with respect to rheology and temperature control for the maintenance of normal spermatogenesis.

Animals↗
PubMed1985

The drooling patient: team evaluation and management.

Drooling is a common problem in neurologically damaged individuals. A surgeon, speech pathologist, physiotherapist and dentist created a "team" to evaluate affected patients. Management by consensus involves both non-surgical and surgical modalities. Bilateral submandibular duct relocation has become the surgical procedure of choice.

Behavior Therapy↗