Biomedical subjects
Publications and source records attributed to B Goldstein.
Enteral feeding by a jejunostomy tube is a reliable and cost-effective method for both long- and short-term nutritional support in selected patients, although a high complication rate has been reported in some series. The authors report on jejunal perforation in an infant, caused by a kinked jejunostomy tube, and emphasize this possible pitfall as a warning to others.
This article briefly reviews the clinical aspects and rationale for therapy with l-deprenyl for several neuropsychiatric conditions, including major depression, Alzheimer's disease, and Parkinson's disease. The rationale for the use of l-deprenyl in these conditions is discussed, and evidence for efficacy is reviewed. Lastly, there is a review of the lack of evidence for l-deprenyl's abuse potential and its use as putative nonspecific cognitive enhancer, a so-called "smart drug." Although l-deprenyl itself appears to have no abuse potential, it is theoretically possible that it might potentiate the actions and frequency of dosage and use of various drugs of abuse or dependence. This is as yet an underresearched area, and more work is required.
During stress, low-frequency (0.01-0.15 Hz) heart rate power and plasma catecholamine levels increase in response to increased sympathetic efferent activity. To test the hypothesis that low-frequency heart rate power, a measure of sympathetic control of heart rate, directly correlates with plasma catecholamine concentrations during periods of increased sympathetic tone, we compared heart rate power spectral measures with antecubital vein norepinephrine, epinephrine, and dopamine concentrations during postural change and after cold pressor testing. We analyzed absolute levels and changes in mean heart rate, respiratory rate, blood pressure, heart rate power spectra, and concentration of norepinephrine, epinephrine, and dopamine in 14 healthy volunteers (seven female/seven male) after postural change and in six (three female/three male) during cold pressor testing. Postural change from supine to standing position resulted in increased heart rate [61 +/- 8 versus 83 +/- 11 (SD) bpm, p < 0.05], diastolic (68 +/- 7 versus 77 +/- 6 mm Hg, p < 0.05) and mean blood pressures (84 +/- 6 versus 91 +/- 9 mm Hg, p < 0.05), norepinephrine concentration (2.09 +/- 1.11 versus 3.23 +/- 1.62 nmol/L, p < 0.05), and low-frequency heart rate power (7.55 +/- 5.63 versus 33.79 +/- 23.55 bpm2, p < 0.05). High-frequency heart rate power, a measure of parasympathetic control of heart rate, decreased with standing (5.38 +/- 4.22 versus 2.94 +/- 2.69 bpm2, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVE: To relate our multi-disciplinary approach to families of brain dead children. DATA SOURCES: The professional experiences of critical care health care providers and the review of the medical and legal literature. SETTING: Paediatric Intensive Care Unit. PARTICIPANTS: Paediatric critical care physicians, primary paediatricians, paediatric critical care nurses, social worker, hospital chaplain and organ procurement coordinator. RESULTS: We describe our multi-disciplinary approach towards education of families of children who have suffered severe brain injury likely to result in brain death. We feel this approach has resulted in better understanding and acceptance of brain death. We also discuss methods of addressing special circumstances around child abuse, religious exemption and organ procurement. CONCLUSION: Our multi-disciplinary approach may assist clinicians and other health care providers in successfully dealing with families of brain dead children.
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We report the use of pressure-controlled inverse-ratio ventilation in two children with acute respiratory failure who were failing conventional mechanical ventilation. The children had subsequent improvement in oxygenation and ventilation without hemodynamic compromise. Pressure-controlled inverse-ratio ventilation was well tolerated by one patient who had increased intracranial pressure secondary to head injury. We were able to successfully hyperventilate, improve oxygenation and control intracranial pressure in this patient while using pressure-controlled inverse-ratio ventilation, which may prove to be an alternative method of ventilation for children with severe lung disease.
Clinical and neuropathologic observations after cervical spinal cord injury suggest varying involvement of gray and white matter. The resulting upper limb weakness may reflect varying degrees of upper motoneuron (UMN) and/or lower motoneuron (LMN) involvement. This study uses electrophysiologic measures, including compound muscle action potential (M response) amplitude, root mean square (RMS) of the surface electromyographic activity during voluntary muscle contractions and the firing rate of motor units, to distinguish UMN and LMN weakness in upper extremities after acute quadriplegia. M response amplitude did not correlate with strength; many muscles had large M responses given their strength. These muscles manifest: (1) high M/RMS ratios (ratio of electrically elicited to voluntarily recruited electromyographic activity) and (2) slow firing rates of single motor units during maximal isometric contractions. For muscles with normal M amplitudes, M/RMS ratio correlates inversely with strength. For muscles with normal M/RMS ratios, M amplitude correlates positively with strength. Cluster analysis was used to distinguish UMN, LMN or Mixed types of weakness. Distinguishing these different types of weakness in acute quadriplegia may allow individualized rehabilitation for the type of weakness present.
Changes in the dimensions of inhaled asbestos fibers in the lung and translocation of intrapulmonary asbestos fibers into mesothelial tissues were investigated in 17 baboons (5 exposed to amosite, 4 to chrysotile, 5 to crocidolite, and 3 unexposed). The animals received different cumulative doses of asbestos by inhalation, followed by varying recovery periods (0-69 months). All asbestos types induced pulmonary asbestosis with severity directly related to the cumulative dose. There were a larger number of asbestos bodies in the lung of the amphibole-exposed animals than in those exposed to chrysotile. A tissue burden study, using transmission electron microscopy on 25-microns paraffin sections, ashed in a low-temperature asher, was performed. Intrapulmonary amosite fibers were shorter in geometric mean length compared with a standard amosite sample (UICC) (3.3 microns). In explanation, it was considered that long fibers might not be able to reach the lower respiratory tract and/or long fibers might be fragmented into shorter fibers. Further, in the amosite-exposed group, the mean length of intrapulmonary fibers increased with the extension of recovery period, suggesting that shorter fibers had been cleared from the lung. The chrysotile standard sample (UICC) had a shorter geometric mean length (1.1 microns) than amosite. The mean length of intrapulmonary chrysotile did not noticeably change with the extension of inhalation and recovery periods; however, the mean width decreased with the extension of these periods. This finding strongly suggested that separation of thick chrysotile fibers had occurred in the lung. The crocidolite standard sample (Transvaal) had a shorter geometric mean length (1.4 microns) than amosite.(ABSTRACT TRUNCATED AT 250 WORDS)
Ten out of 12 South African baboons (Papio ursinus) survived exposure to amosite asbestos dust for periods ranging from 242 days to 898 days at an aerosol level ranging between 1,100 and 1,200 fibers per milliliter. After exposure, they were kept under observation until they died; the total residence time of amosite varied from 1.2-10.2 years. All underwent detailed postmortem necropsy examinations. All baboons had asbestosis. Five of the baboons developed malignant diffuse mesothelioma; three peritoneal, and two pleural with peritoneal invasion. These results indicate that amosite is highly carcinogenic. Since it is difficult to accomplish follow-up of persons exposed to amosite asbestos because of the geographic location of the amosite mines and mills in South Africa (a majority of the workers being migrant laborers from countries bordering on the Transvaal), it is therefore probable that cases of peritoneal mesothelioma have been missed. If human beings are likely to react to amosite as do baboons, epidemiological follow-up should include identification of abdominal as well as thoracic neoplasms.
OBJECTIVE: To study and compare the autonomic cardiovascular state of children after severe brain injury and brain death. DESIGN: Prospective clinical study. SETTING: Pediatric ICU. PATIENTS: Pediatric patients suffering severe brain injury caused by trauma, anoxia, or hemorrhage. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: We analyzed cardiorespiratory parameters, heart rate power spectra, plasma catecholamine concentrations, and the response to the cold pressor test in nine brain-dead patients and compared the results with the test findings of 11 patients with severe brain injury. Low-frequency total heart rate power (p < .03), peak amplitude (p < .02), and plasma catecholamine concentrations (p < .001) were different with no overlap of values between groups. Cold pressor testing in patients with severe brain injury showed changes in respiratory rate and low-frequency heart rate power that were +/- 20% to 100% from baseline values; however, there were no measurable changes in brain-dead patients. CONCLUSIONS: Our results support the concept of a damaged sympathetic cardiovascular system in severe brain injury and complete interruption of the autonomic cardiovascular pathways in brain death. Since determination of brain death may be difficult, our findings have implications for corroborating brain death using autonomic cardiovascular testing.
OBJECTIVES: To assess the frequency of inflicted head injury in critically injured children; the severity of neurologic injury; the neurologic outcome; and the historical, socioeconomic, physical, and radiologic factors associated with inflicted head injury. DESIGN: Prospective clinical study. SETTING: Multidisciplinary pediatric intensive care unit (ICU). PATIENTS: Consecutive cases (n = 40) of severe head injury admitted to a pediatric ICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Fourteen (35%) of 40 cases of head injury were due to inflicted head injury. Eleven (79%) of 14 inflicted head injury cases were due to child abuse and three (21%) were due to neglect. The severity of neurologic injury, as measured by the admission Glasgow Coma Scale, was worse in cases of inflicted head injury (7.1 +/- 0.7 [SE] [inflicted] vs. 9.9 +/- 0.8 [accidental]; p = .04). Glasgow Outcome Scores were worse after inflicted head injury (2 +/- 1 inflicted] vs. 4 +/- 1 [accidental]; p = .004). In victims of child abuse, we found the combination of any two of the following three factors was associated with inflicted head injury: an inconsistent history/physical examination; retinal hemorrhages; or parental risk factors (alcohol or drug abuse, previous social service intervention within the family, or a past history of child abuse or neglect). CONCLUSIONS: This study confirms that severity of neurologic injury and neurologic outcome in cases of inflicted head injury are worse than in any other type of childhood head injury. We believe that a combination of any two of the above three risk factors may prove to be a reliable marker of inflicted head injury in children admitted to a pediatric ICU and will lead to an early and definitive diagnosis.
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The gut of C. elegans derives from all the progeny of the E blastomere, a cell of the eight cell stage. Previous work has shown that gut specification requires an induction during the four cell stage (Goldstein, B. (1992) Nature 357, 255-257). Blastomere isolation and recombination experiments were done to determine which parts of the embryo can respond to gut induction. Normally only the posterior side of the EMS blastomere contacts the inducing cell, P2. When P2 was instead placed in a random position on an isolated EMS, gut consistently differentiated from the daughter of EMS contacting P2, indicating that any side of EMS can respond to gut induction. Additionally, moving P2 around to the opposite side of EMS in an otherwise intact embryo caused EMS's two daughter cells to switch lineage timings, and gut to differentiate from the descendents of what normally would be the MS blastomere. The other cells of the four cell stage, ABa, ABp, and P2, did not form gut when placed in contact with the inducer. To determine whether any other inductions are involved in gut specification, timed blastomere isolations were done at the two and eight cell stages. In the absence of cell contact at the two cell stage, segregation of gut fate proceeded normally at both the two and four cell stages. Gut fate also segregated properly in the absence of cell contact at the eight cell stage. A model is presented for the roles of lineage-dependent mechanisms and cell interactions in establishing gut fate in the E lineage.
The polarization of the embryonic axes is a key event in embryogenesis, being one of the earliest manifestations of the shape and form of the organism. The acquisition of polarity by individual blastomeres is one of the earliest indicators of commitment to a particular pathway of differentiation. These phenomena have been studied in the development of C. elegans both at the cellular and organismal level. This review summarizes what is known about how polarity is established in the blastomeres of this organism, how the division axes of polarized cells are determined, and how the embryonic axes are set up.
Purpuromycin, isolated in our laboratories from the culture broth of Actinoplanes ianthinogenes, is very active in vitro against Gram-positive bacteria and fungi and shows variable activity against Gram-negative bacteria. Its poor bioavailability, probably due to its insolubility in aqueous media at physiological pH's, and the fact that its activity is antagonized by serum, led us to plan a chemical program with the aim of understanding the relevance of the substituents for the antibiotic activity. The original 7-methoxycarbonyl group was transformed into more hydrophilic groups by hydrolysis, by reduction and by ammonolysis or in esters with different degree of lipophilicity and steric hindrance. Almost all of the derivatives retained activity against Gram-positive bacteria but lost activity against Escherichia coli and Trichophyton mentagrophytes. Like purpuromycin, all of the derivatives show a reduced activity in the presence of serum.
Cardiopulmonary monitoring may be desirable during magnetic resonance imaging (MRI) of hemodynamically unstable patients, but must be performed with great caution. This case report describes a severe burn associated with pulse oximetry use during MRI scanning. Risk of this injury is greatest in infants and in individuals with obtundation, general anesthesia, insensate limbs or impairments of verbal communication. Several safety precautions are described. Preparation and monitoring of patients undergoing MRI scanning with cardiopulmonary monitoring should be performed only by specially trained personnel.