Reverse transcriptase mutations in HIV-1-infected children treated with zidovudine

Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) mutations were detected in DNA from peripheral blood mononuclear cells from 11 of 12 HIV-1-infected children after 11-20 months of zidovudine monotherapy. The number of children with mutations detected at each codon were as follows: codon 41, 4; codon 67, 2; codon 70, 7; codon 215, 7; codon 219, 0. Codon 41 mutations were found only in the presence of a codon 215 mutation and in the absence of a codon 70 mutation. The codon 41/215 mutant combination was associated with decline in weight-for-age z score during therapy, weight < 10th percentile, CD4+ cell counts < 3rd percentile, and immune-complex dissociated HIV-1 p24 antigen (ICD p24 Ag) levels > 100 pg/ml. Patients developing the codon 70 mutation tended to have body weight > 30th percentile, CD4+ cell counts > 25th percentile, and ICD p24 Ag < 100 pg/ml. The codon 41 mutation was associated with clinical deterioration during a 6-month followup period.

Blunt popliteal artery injuries

AIMS

To survey the recent results of vascular damage resulting from knee injuries at Middlemore Hospital.

METHOD

A group of sixteen patients treated between 1980-92 were retrospectively analysed.

RESULTS

One patient failed a grafting procedure and required a below knee amputation. Another patient lost two muscle compartments with its associated disability, as a result of pressure necrosis from the acute compartment syndrome. The remaining patients were successfully revascularised.

CONCLUSION

Unless revascularisation is quickly achieved popliteal artery damage associated with knee injuries will lead to frequent leg amputation.

The RNA world of the nucleolus: two major families of small RNAs defined by different box elements with related functions

We have discovered that all known yeast and vertebrate small nucleolar RNAs (snoRNAs), except for the MRP/7-2 RNA, fall into two major classes. One class is defined by conserved boxes C and D and the other by a novel element: a consensus ACA triplet positioned 3 nt before the 3' end of the RNA. A role for the ACA box is snoRNA stability has been established by mutational analysis of a yeast ACA snoRNA (snR 11). Full function of the box depends on the integrity of an adjacent upstream stem. All members of the yeast ACA family are associated with the GAR1 protein. Binding of this or another common small nucleolar ribonucleoprotein particle protein is predicted to be a critical entry point to snoRNA posttranscriptional life, including precise formation of the snoRNA 3' end.

Nitric oxide is generated on the skin surface by reduction of sweat nitrate

Nitric oxide (NO) is known to be synthesized by mammalian cells from L-arginine by a group of NO synthase enzymes. We now show that NO is generated from human skin and propose a different mechanism of production. Whereas enzymatic NO synthesis is inhibited by monomethyl L-arginine, this arginine analog, when infused into the brachial artery at concentrations sufficient to inhibit endothelial NO synthase activity, has little effect on hand skin NO production. Hand skin NO production is increased by topical acidification of the skin surface and greatly increased by the addition of nitrite solutions. We propose that NO generation from skin derives from sweat nitrite (the concentration of which was found to average 3.4 microM in six subjects) due to chemical reduction consequent to the acidic nature of sweat. Sweat contains nitrate in appreciable amounts, and skin commensal bacteria can synthesize nitrate reductase enzyme. Patients on long-term tetracycline antibiotics showed significantly reduced skin NO synthesis, although topical antiseptic and antibiotics had little effect on NO generation in the short-term. We propose that NO generation from skin is dependent on bacterial nitrate reduction to nitrite and subsequent reduction by acidification. We speculate that this has a physiologic role in the inhibition of infection by pathogenic fungi and other susceptible microorganisms and may affect cutaneous T-cell function, keratinocyte differentiation, and skin blood flow.

Amplification of MDM2 inhibits MyoD-mediated myogenesis

One obvious phenotype of tumor cells is the lack of terminal differentiation. We previously classified rhabdomyosarcoma cell lines as having either a recessive or a dominant nondifferentiating phenotype. To study the genetic basis of the dominant nondifferentiating phenotype, we utilized microcell fusion to transfer chromosomes from rhabdomyosarcoma cells into C2C12 myoblasts. Transfer of a derivative chromosome 14 inhibits differentiation. The derivative chromosome 14 contains a DNA amplification. MDM2 is amplified and overexpressed in these nondifferentiating hybrids and in the parental rhabdomyosarcoma. Forced expression of MDM2 inhibits MyoD-dependent transcription. Expression of antisense MDM2 restores MyoD-dependent transcriptional activity. We conclude that amplification and overexpression of MDM2 inhibit MyoD function, resulting in a dominant nondifferentiating phenotype.

Ubiquitination of protein kinase C-alpha and degradation by the proteasome

Bryostatins and phorbol esters acutely activate and subsequently down-regulate protein kinase C (PKC) by inducing its proteolysis via an unknown pathway. Here we show that treatment of renal epithelial cells with bryostatin 1 (Bryo) produced novel PKC-alpha species, which were larger than the native protein (80 kDa). The >80 kDa PKC-alpha species contained Ubi as indicated by immunostaining and accumulated in the presence of lactacystin, a selective inhibitor of proteolysis by the proteasome. In vitro experiments with 125I-ubiquitin and membranes from Bryo-treated cells showed that PKC-alpha became ubiquitinated by a reaction that depended on ATP and a cytosolic fraction. Lactacystin or a peptidyl aldehyde, Bz-Gly-Leu-Ala-leucinal, which inhibits certain proteinase activities of the proteasome, inhibited Bryo-evoked disappearance of PKC-alpha protein from the cells. Lacta preserved Bryo-induced 32P-labeled PKC-alpha indicating that the proteasome inhibitor spared activated enzyme from down-regulation in vivo. These findings show that Bryo induces the degradation of PKC-alpha by the ubiquitin-proteasome complex.

Polymorphic markers in apolipoprotein C-III gene flanking regions and hypertriglyceridemia

Hypertriglyceridemia and hyperlipidemia are common disorders associated with coronary artery disease and premature death. The proteins encoded by the apolipoprotein (apo) A-I/C-III/A-IV gene cluster are involved in the metabolism of both triglycerides and cholesterol. In a large sample of individuals from the ARIC study, six polymorphic markers were typed and plasma lipid values were measured to determine whether the well-established association between the Sst I S2 allele in the 3'-untranslated region of the apo C-III gene and hypertriglyceridemia was due to disequilibrium with variation in the 5' regulatory region of the apo C-III gene. The Sst I polymorphism was significantly associated with hypertriglyceridemia (P = .006) but not with carotid artery wall thickness, plasma apo C-III levels, or elevated cholesterol. The frequency of the S2 allele was 0.14 in those with high triglyceride levels and 0.05 in those with low triglyceride levels. None of the 5' flanking polymorphisms were significantly associated with any of the plasma lipids studied. There was substantial linkage disequilibrium between the Sst I polymorphism and each of the 5' apo C-III polymorphisms; however, the significant association between the apo C-III haplotypes and hypertriglyceridemia (odds ratio, 4.0; P < .0001) was solely attributable to the effects of the Sst I polymorphism (odds ratio, 3.96). As a part of these analyses, we also defined a unique haplotype that is inversely associated with the occurrence of hypertriglyceridemia, suggesting further molecular analyses of this important gene region.

Effect of interferon therapy on bile duct inflammation in hepatitis C

Inflammation of the bile ducts was studied in liver biopsies from patients with chronic hepatitis C to determine whether the frequency of inflamed bile ducts changes with therapy and correlates with other histological variables and expression of class I and II MHC antigens on ductal epithelium. Twenty patients treated at UMMC between 1991 and 1994 underwent needle biopsies of the liver before and after therapy with interferon alpha 2B (IFN). A complete response to therapy was defined as a return to normal serum alanine aminotransferase levels occurring and persisting during therapy. The number of inflamed bile ducts/total ducts (%IBDs), presence of piecemeal necrosis and lymphoid aggregates, and grade of inflammation were assessed in each high-power field in all areas with bile ducts. The frequencies of these variables were compared in cirrhotics and non-cirrhotics and in patients with complete or incomplete responses to IFN. Frozen sections of biopsies from 5 patients were immunostained using antibodies to HLA-DR and B-2 microglobulin, and positive staining was noted on bile ducts. Before therapy, the %IBD was slightly greater in patients with cirrhosis. After IFN, both %IBD and serum alkaline phosphatase levels decreased in non-cirrhotics who responded to IFN. The change in frequency of IBD with IFN paralleled the changes in the other histological features. No correlation was noted between bile duct inflammation and expression of class I and II antigens. The conclusion is that inflammation of the bile ducts occurs frequently in chronic hepatitis C, correlates with other features of inflammation in the triads, and decreases in response to IFN therapy.

Dephosphorylation of activated protein kinase C contributes to downregulation by bryostatin

We show that bryostatin 1 (Bryo) rapidly produces an inactive, incompetent 76-kDa form of protein kinase C-alpha (PKC-alpha) in the LLC-MK2 line of renal epithelial cells. Bryo, like phorbol 12-myristate 13-acetate (PMA), acutely activated PKC, as indicated by autophosphorylation and translocation of PKC-alpha, the predominant PMA-sensitive isoform expressed by the cells. Bryo concomitantly increased the 32P labeling of 80-kDa PKC-alpha by autophosphorylation and produced a 76-kDa form of PKC-alpha that lacked detectable 32P. The 76-kDa form was in the particulate rather than the cytosolic fraction, which suggests that it was produced from activated kinase. Alkaline phosphatase treatment of immunoprecipitated PKC-alpha converted the 80-kDa form to 76 kDa, but it had no effect on the mobility of the 76-kDa form, suggesting that it was not phosphorylated. Pulse-chase labeling of PKC-alpha with [35S]Met/Cys indicated that there is a precursor-product relationship between the 80- and 76-kDa forms, respectively. Inhibition of protein synthesis had no effect on the production of 76-kDa PKC-alpha by Bryo. PMA also produced 76-kDa PKC-alpha but was less potent and efficacious than Bryo. Bryo produced a more rapid loss of 80-kDa PKC-alpha protein and total Ca(2+)- and phospholipid-dependent PKC activity than PMA. The 76-kDa form is inactive and incompetent because it lacked detectable 32P under conditions that strongly autophosphorylated the 80-kDa form. We suggest that dephosphorylation predisposes PKC to proteolysis, and greater production of the 76-kDa form explains the more efficient downregulation of the kinase by Bryo vs. PMA.

The myth of the fecalith

A radiographically demonstrated fecalith is widely considered a virtually pathognomonic sign of acute appendicitis. This case report describes a patient with a clinical presentation suggestive of appendicitis and a well-defined right lower quadrant fecalith who was found to have a normal appendix at surgery. This case calls into question the venerable dogma surrounding the fecalith and highlights the necessity for the physician to continue to rely on clinical judgment in making the diagnosis of appendicitis.

Biphenyl-derivatives of 2-amino-7-phosphono-heptanoic acid, a novel class of potent competitive N-methyl-D-aspartate receptor antagonists--II. Pharmacological characterization in vivo

A selection of biphenyl-analogues of 2-amino-7-phosphonoheptanoic acid (AP7), N-methyl-D-aspartate (NMDA) receptor antagonists with high affinity in vivo efficacy. The lead compound SDZ EAB 515 was found to inhibit L-phenylalanine uptake by the large neutral amino acid carrier in vitro and in vivo; active transport may thus confer a good bioavailability to this class of compounds. CNS effects were demonstrated by significant changes in 2-deoxyglucose-uptake in various brain regions at doses from 1 to 10 mg/kg i.p. With the most active agent, SDZ 220-581, full protection against maximal electroshock seizures (MES) was obtained at oral doses of 10 mg/kg in rats and in mice. The compound had a fast onset (< or = 1 hr) and a long duration (> or = 24 hr) of action. Motor-debilitating effects (impairment of rotarod performance) occurred at doses about 10 times higher than those required for protection against MES. Neuroprotective activity was demonstrated by the ability of the compounds to reduce the extent of quinolinic acid-induced striatal lesions in rats, in the dose range of 3-15 mg/kg (i.p.) or 10-50 mg/kg (p.o.). In the middle cerebral artery occlusion (MCAO) model of focal cerebral ischemia in rats, the test compounds reduced the infarct size by 40-50% when given i.v. before or by 20-30% when given i.v. 1 hr after MCAO. SDZ 220-581 provided 20-30% protection at > or = 2 x 10 mg/kg p.o. This compound also showed analgesic activity at low oral doses in a model of neuropathic pain, although higher doses were required in model of mechanical inflammatory hyperalgesia. Unexpectedly, SDZ 220-581 at low s.c. doses counteracted the antiparkinsonian effects of L-DOPA in MPTP-treated marmosets. (Sub)chronic administration of SDZ 220-581 did not reduce its ability to protect against quinolinic acid neurotoxicity, and no upregulation of NMDA receptors was detected using a [3H]CGP-39653 binding assay. In conclusion, from a series of biphenyl-AP7-derivatives, SDZ 220-581 is clearly the most active compound in vivo. Its pharmacological profile with a good, long-lasting oral activity might open up novel therapeutic applications for competitive NMDA receptor antagonists.

Medical students' attitudes toward the autopsy

BACKGROUND

The autopsy is an educational experience that helps students correlate clinical findings with basic science issues. Because of the sensitive nature of the autopsy, students' attitudes should be considered prior to its design and implementation.

METHOD

In 1992-1993, all 147 second-year students at the Medical College of Ohio completed a 26-item Likert questionnaire about their attitudes toward the autopsy. After participating in an elective autopsy experience, 26 students completed the same questionnaire plus 18 additional questions about the environment and behavior of the pathologist. Pre- and post-autopsy responses were factor analyzed using principal-components analysis with a varimax rotation. Student's t-tests were used to compare (1) the pre-autopsy factor scores of the elective participants and the rest of the class and (2) the pre- and post-autopsy scores of the participants.

RESULTS

Factor analysis of the attitude questions identified seven factors. Comparison of the pre- and post-autopsy scores of the elective participants revealed statistically significant positive increases on four factors; three factors remained positive or neutral.

CONCLUSION

It was concluded that the autopsy elective had a positive influence on the student's attitudes. In addition, the pathologist's behavior and the environment in which the autopsy occurred influenced the students. Twenty-two (85%) of the students indicated the autopsy should be mandatory for all students.

An approach to investigating linkage for bipolar disorder using large Costa Rican pedigrees

Despite the evidence that major gene effects exist for bipolar disorder (BP), efforts to map BP loci have so far been unsuccessful. A strategy for mapping BP loci is described, focused on investigation of large pedigrees from a genetically homogenous population, that of Costa Rica. This approach is based on the use of a conservative definition of the BP phenotype in preparation for whole genome screening with polymorphic markers. Linkage simulation analyses are utilized to indicate the probability of detecting evidence suggestive of linkage, using these pedigrees. These analyses are performed under a series of single locus models, ranging from recessive to nearly dominant, utilizing both lod score and affected pedigree member analyses. Additional calculations demonstrate that with any of the models employed, most of the information for linkage derives from affected rather than unaffected individuals.

Mapping of the ARIX homeodomain gene to mouse chromosome 7 and human chromosome 11q13

The recently described homeodomain protein ARIX is expressed specifically in noradrenergic cell types of the sympathetic nervous system, brain, and adrenal medulla. ARIX interacts with regulatory elements of the genes encoding the noradrenergic biosynthetic enzymes tyrosine hydroxylase and dopamine beta-hydroxylase, suggesting a role for ARIX in expression of the noradrenergic phenotype. In the study described here, the mouse and human ARIX genes are mapped. Using segregation analysis of two panels of mouse backcross DNA, mouse Arix was positioned approximately 50 cM distal to the centromere of chromosome 7, near Hbb. Human ARIX was positioned through analysis of somatic cell hybrids and fluorescence in situ hybridization of human metaphase chromosomes to chromosome 11q13.3-q13.4. These map locations extend and further define regions of conserved synteny between mouse and human genomes and identify a new candidate gene for inherited developmental disorders linked to human 11q13.

Levels of soluble cell adhesion molecules in patients with dyslipidemia

BACKGROUND

Increased expression of cell adhesion molecules (CAMs) on the vascular endothelium has been postulated to play an important role in atherogenesis. Both in vitro and in vivo studies have suggested that dyslipidemia may increase expression of CAMs.

METHODS AND RESULTS

To determine whether dyslipidemia is associated with increased expression of CAMs, we examined the levels of soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), and soluble E-selectin (sE-selectin) in individuals with either hypercholesterolemia or hypertriglyceridemia and in control subjects matched for age and sex. Patients with hypertriglyceridemia had significantly higher levels of sVCAM-1 (739 +/- 69 ng/mL) compared with patients with hypercholesterolemia (552 +/- 63 ng/mL) and control subjects (480 +/- 56 ng/mL). Levels of sICAM-1 were significantly increased in both the hypercholesterolemic and hypertriglyceridemic groups (298 +/- 29 and 342 +/- 31 ng/mL, respectively) compared with the control group (198 +/- 14 ng/mL). Levels of sE-selectin were significantly increased in hypercholesterolemic patients (74 +/- 9 ng/mL) compared with control subjects (48 +/- 5 ng/mL). Ten hypercholesterolemic patients were treated aggressively with atorvastatin alone or a combination of colestipol and either atorvastatin or simvastatin for a mean of 42 weeks and had an average LDL cholesterol reduction of 51%. Comparison of soluble CAMs before and after treatment showed a significant reduction only in sE-selectin (77 +/- 11 versus 56 +/- 6 ng/mL, P < or = .03) but not for sVCAM-1 or sICAM-1.

CONCLUSIONS

Although severe hyperlipidemia is associated with increased levels of soluble CAMs, aggressive lipid-lowering treatment had only limited effects on the levels. Increased levels of soluble CAMs in patients with hyperlipidemia may be a marker for atherosclerosis.

Vision, cognition and developmental characteristics of girls and women with Rett syndrome

Forty-two females with Rett syndrome, aged 2.5 to 47 years, were assessed with the Teller Acuity Cards and a new version of the Fagan test for age 2 years and above, and their parents were interviewed about the children's communication skills. The visual function of the subjects indicated arrested development, and they scored significantly lower on the Fagan test than a normal comparison group. Their visual processing and memory deteriorated somewhat with age, while those of the comparison group showed a slight increase. Both age at onset of Rett syndrome symptomatology and speech measures were inversely correlated with visual processing and memory, indicating that age at recession may have differential consequences for different functions. Among the subjects, persistent looking was associated with low cognitive function. The results have implications for intervention, and demonstrate that the paradigm of preferential looking may be useful in cognitive assessment of females with Rett syndrome.

An appraisal of the antiparkinsonian activity of piribedil in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated common marmosets

The D2 dopamine agonist piribedil is not widely used in the treatment of Parkinson's disease because it was thought to be effective mainly on parkinsonian tremor and to produce a high incidence of peripheral side effects, particular nausea. In this study, we used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated primates to reevaluate the antiparkinsonian ability of piribedil after its oral administration in the presence or absence of domperidone pretreatment. Adult common marmosets (Callithrix jacchus) were treated with the nigral toxin MPTP to induce a parkinsonian syndrome characterised primarily by bradykinesia and other motor deficits. Oral administration of a solution of piribedil [1-(3,4-methylenedioxybenzyl)-4-(2-pyrimidinyl)piperazine] produced a dose-related reversal of all MPTP locomotor and behavioural deficits. However, this effect was short lived and associated with unwanted effects, particular nausea and retching, which clearly hindered locomotion. In contrast, after pretreatment with the peripheral dopamine antagonist domperidone, administration of piribedil did not induce nausea or retching in MPTP-treated marmosets. In these animals, piribedil caused a more marked and longer lasting enhancement of locomotor activity and a further reduction in behavioural deficits than that observed after administration of piribedil alone. In addition, piribedil induced increased vigilance and awareness. These data show that piribedil can reverse akinesia and rigidity in MPTP-treated primates. In addition, they show the drug to be effective without peripheral side effects when used in conjunction with domperidone. These data indicate that piribedil should be an effective monotherapy for Parkinson's disease.