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Biomedical subjects

S Perlman

Publications and source records attributed to S Perlman.

At least 91 records · Page 5Linked to original sources
PubMed1992

Intracellular processing of the N-terminal ORF 1a proteins of the coronavirus MHV-A59 requires multiple proteolytic events.

Several polypeptide products of MHV-A59 ORF 1a were characterized in MHV-A59 infected DBT cells, using antisera directed against fusion proteins encoded in the first 6.5 kb of ORF1a. These included the previously identified N-terminal ORF 1a product, p28, as well as 290-, 240-, and 50-kDa polypeptides. P28 was always detected as a discrete band without larger precursors, suggesting rapid cleavage of p28 immediately after its synthesis. Once p28 was cleaved there was little degradation of the protein over a 2-hr period. The intracellular cleavage of p28 was not inhibited by the protease inhibitor leupeptin, in contrast to results obtained during in vitro translation of genome RNA (Denison and Perlman, 1986). These data suggest that different protease activities may be responsible for the cleavage of p28 in vitro and in vivo. The 290-kDa protein was an intermediate cleavage product derived from a precursor of greater than 400 kDa. The 290-kDa product was subsequently cleaved into secondary products of 50 and 240 kDa. The intracellular cleavage of the 290-kDa polypeptide was inhibited by leupeptin at concentrations which did not inhibit the early cleavage of p28 or the cleavage of the 290-kDa product from its larger polyprotein precursor. In the presence of zinc chloride, a product of greater than 320 kDa was detected, which appears to incorporate p28 at its amino terminus. This suggests that at least two protease activities may be necessary for processing of ORF1a proteins, one of which cleaves p28 and is sensitive to zinc chloride but resistant to leupeptin, and the other which cleaves the 290-kDa precursor and is sensitive to both inhibitors. Both the 290- and 240-kDa proteins should contain sequences predicted to encode two papain-like protease activities.

Leupeptins↗
PubMed1992

Renal nerves modulate kidney renin gene expression during the transition from fetal to newborn life.

The role of renal nerves in regulating changes in plasma renin activity (PRA) and renal renin gene expression was studied in intact (n = 6) and denervated (n = 6) fetal sheep before birth and during the first 24 h after delivery. Renal denervation completely blunted the rise in PRA observed 24 h after delivery in newborn lambs; in lambs with intact kidneys, PRA increased significantly (P less than 0.05) from 3.26 +/- 0.60 (predelivery) to 6.34 +/- 1.85 ng angiotensin I (ANG I).ml-1.h-1 (24 h postdelivery), while in lambs with denervated kidneys, predelivery and post-delivery values were 2.84 +/- 0.19 and 2.49 +/- 0.45 ng ANG I.ml-1.h-1, respectively. Renin mRNA levels were significantly lower (P less than 0.001) in denervated than in intact kidneys 24 h after birth. A close analysis of these results also revealed that renin mRNA levels were significantly higher (P less than 0.001) in intact kidneys of newborn lambs delivered vaginally (n = 3) than in newborn lambs delivered by cesarean section (n = 3). These results suggest that renal nerves play an important role in regulating renin gene expression and PRA during the transition from fetal to newborn life.

Aging↗
PubMed1991

Negative regulation of angiotensinogen gene expression by glucocorticoids in fetal sheep liver.

The effect of glucocorticoids in regulating liver angiotensinogen gene expression was studied in chronically instrumented fetal sheep during the last trimester of gestation and was compared with the expression of other hepatic genes (prothrombin, factor IX, and albumin). Four sets of twins were studied at 118 d of gestation, and three sets were studied at 138 d of gestation (term, 145 d). One of each set of twins was infused intraperitoneally with cortisol (5 mumol.mL-1.h-1) for 48 h, whereas the other twin received the same volume (1 mL/h) of normal saline. Plasma cortisol concentration increased from 0.32 +/- 0.12 and 2.7 +/- 0.12 nmol/100 mL to 44.2 +/- 20.0 and 37.7 +/- 8.2 nmol/100 mL in 118- and 138-d fetuses, respectively, during the cortisol infusion; no changes were observed in fetuses infused with saline alone. At the end of the infusion period, the animals were anesthetized, the fetal liver was removed, and total cellular RNA was isolated and probed for angiotensinogen, prothrombin, factor IX, and albumin. The results demonstrated that cortisol infusion decreased angiotensinogen mRNA by 61% in 138-d fetuses and albumin mRNA expression by 2.4-fold in 118-d fetuses and by 3.4-fold in 138-d fetuses. On the other hand, cortisol had no effect on fetal factor IX gene expression but increased prothrombin mRNA levels by 65% in 118-d fetuses and 62% in 138-d fetuses. Taken together, our results suggest that, during fetal life, angiotensinogen gene expression is negatively regulated by glucocorticoids. This effect is not universal because cortisol increases fetal prothrombin gene expression.

Angiotensinogen↗
PubMed1990

Effect of olfactory bulb ablation on spread of a neurotropic coronavirus into the mouse brain.

Previous results suggested that, after intranasal inoculation, mouse hepatitis virus (MHV), a neurotropic coronavirus, entered the central nervous system (CNS) via the olfactory and trigeminal nerves. To prove this hypothesis, the effect of interruption of the olfactory pathway on spread of the virus was studied using in situ hybridization. Unilateral surgical ablation of this pathway prevented spread of the virus via the olfactory tract on the side of the lesion. MHV RNA could be detected, however, at distal sites on the operated side, indicating that the virus spread via well-described circuits involving the anterior commissure from the control (intact) side of the brain. Viral transport via the trigeminal nerve was not affected by removal of the olfactory bulb, showing that the surgical procedure was specific for the olfactory pathway. These results prove conclusively that MHV gains entry to the CNS via a transneuronal route, and spreads to additional sites in the brain via known neuroanatomic pathways.

Animals↗
PubMed1990

Localization of virus and antibody response in mice infected persistently with MHV-JHM.

Suckling mice infected intranasally with MHV-JHM and nursed by immunized dams develop a late onset demyelinating encephalomyelitis. Analysis by in situ hybridization revealed that MHV-JHM entered the central nervous system (CNS) via the olfactory and trigeminal nerves and spread over the next two weeks to the spinal cord, prior to amplification at this site. Serial measurements of neutralizing antibody titers showed that the late onset disease developed in some mice at levels of antibody which protected mice from the fatal, acute encephalitis, supporting the notion that cell-mediated and not humoral immunity is important in protecting mice from MHV-JHM persistence.

Animals↗
PubMed1990

Identification of the spinal cord as a major site of persistence during chronic infection with a murine coronavirus.

After intranasal inoculation, mouse hepatitis virus (MHV) gains entry into the central nervous system (CNS) via the olfactory and trigeminal nerves. Under the appropriate conditions, some mice develop clinically apparent demyelinating encephalomyelitis several weeks later, with virus always present in the spinal cord. To determine the pathway by which virus reaches the cord, brains and spinal cords of infected, asymptomatic mice were analyzed by in situ hybridization. Viral RNA was always detected in the anterior part of the upper spinal cord. A similar analysis of mice with the recent onset of hindlimb weakness showed that viral RNA was detected in the same location. The results suggest that MHV is transported to the spinal cord via well-defined neuroanatomic pathways and that viral amplification with resultant clinical disease occurs from this site of persistence in the anterior spinal cord. This process of viral amplification may involve the generation of viral variants as has been described for MHV-infected rats. No major changes in viral RNA or protein could be detected when MHV isolated from mice with hindlimb paralysis was analyzed. The data suggest that the generation of viral variants is not important in the pathogenesis of the late onset of neurological disease induced by MHV in mice.

Animals↗
PubMed1990

Developmental regulation of angiotensinogen gene expression in sheep.

It has been suggested that the liver is not the main source of angiotensinogen during fetal life in rats, but that the kidney is an important site of fetal angiotensinogen synthesis. In an effort to determine if this phenomenon is specific to the rat or applicable to other species, we compared the ontogenic changes in hepatic and renal angiotensinogen mRNA expression in fetal (60, 90, 118, and 138 d of gestation, term being 145 d), newborn (7 d postnatal), and adult sheep. Total RNA was extracted, subjected to Northern blotting and hybridized using a full-length rat radiolabeled antisense RNA. Angiotensinogen mRNA sequences were detected in all fetal liver samples and appeared to increase 3-fold from 60 to 138 d gestation and then to decrease after birth. In contrast, angiotensinogen mRNA could not be detected in renal cortical tissue of 118 or 138 d fetuses, or newborn or adult sheep. We conclude that, unlike in the rat, liver angiotensinogen gene expression is detectable during the 2nd trimester of gestation in sheep and is developmentally regulated. Furthermore, in contrast to the fetal rat, angiotensinogen mRNA sequences were undetectable in fetal sheep kidney.

Angiotensinogen↗
PubMed1990

The pathogenesis of murine cytomegalovirus ocular infection. Anterior chamber inoculation.

To investigate the pathogenesis of ocular cytomegalovirus infections, 3-week-old BALB/c mice were inoculated with 10(4) plaque-forming units of murine cytomegalovirus (MCMV) by the right anterior chamber and studied sequentially with the use of virus assays and in situ nucleic acid hybridization methods. During acute infection, MCMV was recovered from the right vitreous, lens, cornea, retina/choroid, and optic nerve. Titers of MCMV exceeded 10(3) per ml of homogenate on days 4 and 7 after inoculation. With the use of biotinylated MCMV DNA probes, MCMV nucleic acids were detected in and adjacent to cells of the iris and ciliary body and occasionally within inflammatory lesions of the cornea. During chronic infection, MCMV was recovered, with the use of co-cultivation or explant methods, from ocular tissues of occasional mice inoculated with MCMV 1 yr earlier. Infectious MCMV was also recovered from the ocular homogenates of a group of mice immunosuppressed with antilymphocyte serum and cortisone. These studies indicate that cells of the uveal tract are permissive for MCMV and suggest that intrinsic persistence or latency of cytomegalovirus in ocular tissues could contribute to the pathogenesis of ocular infections in immunosuppressed hosts.

Acute Disease↗
PubMed1990

Role of a pharmacist in a seizure clinic.

The involvement of a clinical pharmacist in a Department of Veterans Affairs seizure clinic is described. A pharmacist who had served a residency in ambulatory care began working in a seizure clinic in 1988 after obtaining the cooperation of a neurologist interested in a multidisciplinary approach to patient care. A clinical protocol was developed to guide the pharmacist's participation. The seizure clinic is staffed by the clinical pharmacist, a pharmacy resident, and a neurologist and is currently treating 162 adult male veterans. Of the 162 patients, 159 are receiving anti-convulsant therapy. The role of the pharmacist is to assist the neurologist in providing patient-care services. The pharmacist interviews each patient, performs a neurological assessment and mental status evaluation, and orders laboratory tests. Information is recorded by the pharmacist on a history form and a subjective and objective assessment and planning form. The pharmacist presents the findings to the neurologist, and the patient is then interviewed jointly by the pharmacist and the neurologist. Between appointments, the pharmacist follows up on abnormal laboratory test values and informs patients of any necessary dosage adjustments. More time is available for patient care, there has been an increase in the detection of adverse drug reactions and disease states, and record keeping has improved. A pharmacist assumed a primary-care role in a seizure clinic by interviewing and assessing patients, ordering laboratory tests, and participating in the selection and adjustment of anticonvulsant therapy.

Ambulatory Care Facilities↗
PubMed1990

Super bone scan in metastatic stomach cancer.

Within the imaging literature, the super bone scan has emerged as a distinct type of bone scan with a specific differential diagnosis. Previous reviews have included prostate, breast, bladder and colon cancer, and lymphoma among the causes of a super bone scan but have not included stomach cancer. We report a super bone scan caused by late recurrence of stomach cancer in the bone marrow. Because the management of stomach cancer is significantly different than the management of other causes of a super bone scan, the distinction is clinically relevant. We conclude that stomach cancer should be considered in the differential diagnosis of a super bone scan.

Adenocarcinoma↗
PubMed1989

Idiopathic central diabetes insipidus followed by progressive spastic cerebral ataxia. Report of four cases.

A distinctive syndrome of diabetes insipidus developed in four boys in early childhood and progressive spastic cerebellar ataxia developed in adolescence. The boys have been observed for 12 to 19 years and are currently 19 to 25 years old. In patient 1, 12 years after the onset of diabetes insipidus and 4 years after the onset of spastic cerebellar ataxia, bone lesions that proved to be histiocytosis were detected. In patient 2, calcification that developed in the cerebellar dentate nuclei was similar to calcification described in patients with histiocytosis. In the other two patients, an etiologic diagnosis has not been established. We conclude that there is a distinctive syndrome characterized by early diabetes insipidus with subsequent progressive spastic cerebellar ataxia. While histiocytosis may not account for this complex syndrome in all cases, diabetes insipidus followed by progressive spastic cerebellar ataxia merits intensive evaluation.

Adult↗
PubMed1989

Spread of a neurotropic murine coronavirus into the CNS via the trigeminal and olfactory nerves.

The route of entry into the central nervous system (CNS) of most neurtropic viruses has not been established. The coronavirus, mouse hepatitis virus strain JHM (MHV-JHM), causes acute encephalomyelitis and acute and chronic demyelinating diseases and is an important model system for virus-induced neurological disease. Suckling C57BL/6 mice infected intranasally with MHV-JHM develop either the acute encephalomyelitis or a late onset, symptomatic demyelinating encephalomyelitis, depending on whether they are nursed by unimmunized or immunized dams. Analysis by in situ hybridization was used to determine the route of entry of MHV-JHM into the CNS in these mice. At early times, viral RNA was detected only in the trigeminal and olfactory nerves and in their immediate connections in all mice. A few days later, MHV-JHM RNA was found throughout the brain in mice dying of the acute encephalomyelitis, but remained confined to the entry sites in mice which did not develop acute disease. These results suggest that MHV-JHM enters the CNS via an interneuronal route in all mice, but that the presence of maternal antibody prevents the dissemination of virus via extracellular fluid. In addition, MHV-JHM may establish low-level persistence in the trigeminal or olfactory nerve or in one of its connections in mice that do not develop acute encephalomyelitis.

Acute Disease↗
PubMed1989

Fusiform bacterial sepsis. Metastases with osteomyelitis and hepatic abscess occurring in a chaotic family.

Cases of fusiform bacteria sepsis have been reported infrequently in the pediatric literature. This case demonstrates the severe metastatic complications of fusiform bacterial sepsis including osteomyelitis, with multiple pathological fractures, sepsis, and abscesses of the liver. In the diagnostic evaluation of the etiology for this uncommon infection, child abuse was discovered in all children of this family. In children with uncommon infections and no underlying etiology, child abuse should be considered.

Child Abuse↗
PubMed1988

Regional localization of virus in the central nervous system of mice persistently infected with murine coronavirus JHM.

Suckling C57BL/6 mice infected with mouse hepatitis virus strain JHM (MHV-JHM) develop either a fatal acute encephalomyelitis or a late onset demyelinating disease, depending on whether they are nursed by unimmunized or immunized dams. To determine the localization of virus-specific RNA, serial sections of brains from infected and uninfected mice were annealed with a 35S-labeled antisense RNA probe and analyzed by film autoradiography. In the mice with acute encephalomyelitis, viral RNA was present in the mesencephalon, hypothalamus, hippocampus, basal ganglia, subcortical white matter, and thalamus. Viral RNA was detected in the spinal cords of all mice with the late onset, demyelinating encephalomyelitis, but was distributed into three different patterns in the brains of these mice, even though all had the same clinical disease. In the first group, viral RNA was detected only in the brainstem. In the second group, viral RNA was detected in the brainstem, thalamus, and cerebral grey matter. This distribution was consistent with viral spread along well-defined tracts connecting these parts of the brain. In the third group, viral RNA could be detected both in the brainstem and in several white matter tracts within close physical proximity to the optic chiasm. This distribution was consistent with viral spread by an extracellular route from one white matter tract to other tracts which were physically close, but which were not part of the same pathways. These results suggest that MHV-JHM spreads through the central nervous system both along well-defined neuronal pathways and by spread from contiguous structures, but also suggest that viral replicates preferentially in a limited number of areas of the brain. The technique of in situ hybridization with film autoradiography should be generally useful for analyzing macroscopic movements of virus within infected organs.

Animals↗
PubMed1988

Detection of a murine coronavirus nonstructural protein encoded in a downstream open reading frame.

Mouse hepatitis virus (MHV) gene 5 contains two open reading frames. We have expressed the second open reading frame of this gene (gene 5 ORF 2) in an Escherichia coli expression system. This system utilized a plasmid which contained the promoter and the first 36 codons of the recA gene fused in frame with the MHV gene 5 ORF 2, which is fused in turn to the beta-galactosidase gene. The protein product of this gene fusion was used to raise antibody to gene 5 ORF 2. The specificity of the antibody was verified by immunoprecipitation of the in vitro transcribed and translated protein product of gene 5 ORF 2. The second reading frame of MHV gene 5 was shown to be expressed during the course of infection by immunocytochemistry and radioimmunoprecipitation using the antibody raised against the E. coli fusion protein and by two-dimensional gel electrophoresis.

Genes↗
PubMed1988

Experimental control of the differentiation of Leydig cells in the rat fetal testis.

In the developing fetal testis, in vitro as well as in vivo, two kinds of endocrine cells differentiate successively: Sertoli cells, which produce the Müllerian inhibitor (or anti-Müllerian hormone) and aggregate with germ cells into seminiferous cords; and Leydig cells, which release androgens. Serum added to the synthetic culture medium prevents the morphogenesis of the seminiferous cords but not the cytodifferentiation of the endocrine cells. L-Azetidine 2-carboxylic acid (LACA), a proline competitor, introduced into the medium also prevents differentiation of seminiferous cords. In the present experiments, the effects of LACA on the endocrine cells were studied. It did not suppress production of the Müllerian inhibitor, but it opposed differentiation of Leydig cells. Histochemically detectable 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) was virtually absent and the release of testosterone, delta 4-androstenedione, 17-hydroxyprogesterone, or progesterone into the medium became undetectable. Moreover, dibutyryl cAMP added to the medium during the final day in vitro had very little effect on the parameters of steroidogenesis. An excess of proline added to the LACA-containing medium permitted normal morphogenesis of seminiferous cords, normal steroidogenesis, and normal response to cAMP. LACA did not prevent the appearance of 3 beta-HSD activity in the adrenals, nor did it reduce the expression of laminin and fibronectin (data not shown) in the mesonephric structures as much as in the testes. The differentiation of the testis and especially of the Leydig cells appears to have special requirements for proline.

17-alpha-Hydroxyprogesterone↗