US national estimation of emergency department utilization by patients given 'HIV/AIDS-related illness' as their primary diagnosis.

BACKGROUND: The emergency department (ED) is one of the most frequent sources of medical care for many HIV-infected individuals. However, the characteristics and ED utilization patterns of patients with HIV/AIDS-related illness as the primary ED diagnosis (HRIPD) are unknown. METHODS: We identified the ED utilization patterns of HRIPD visits from a weighted sample of US ED visits (1993-2005) using the National Hospital Ambulatory Medical Care Survey, a nationally representative survey. Data on visits by patients≥18 years old were analysed using procedures for multiple-stage survey data. We compared the utilization patterns of HRIPD vs. non-HRIPD visits, and patterns across three periods (1993-1996, 1997-2000 and 2001-2005) to take into account changes in HIV epidemiology. RESULTS: Overall, 492 000 HRIPD visits were estimated to have occurred from 1993 to 2005, corresponding to 5-in-10 000 ED visits. HRIPD visits experienced longer durations of stay (5.2 h vs. 3.4 h; P=0.001), received more diagnostic tests (5.1 vs. 3.3; P<0.001), were prescribed more medications (2.5 vs. 1.8; P<0.001) and were more frequently seen by physicians (99.5%vs. 93.8%; P<0.001) compared with non-HRIPD visits. HRIPD visits were more likely to result in admission [adjusted odds ratio (OR) 7.67; 95% confidence interval (CI) 5.14-11.44]. The proportion of HRIPD visits that required emergent/urgent care or were seen by attending physicians, and the number of diagnostic tests ordered, significantly increased over time (P<0.05), while the wait time (P=0.003) significantly decreased between the second and third study periods (P<0.05). CONCLUSIONS: Although HRIPD visits were infrequent relative to all ED visits, HRIPD visits utilized significantly more resources than non-HRIPD visits and the utilization also increased over time.

High-risk sexual behaviours and genital chlamydial infections in high school students in Southern Taiwan.

The objective of this study was to determine the prevalence of high-risk sexual behaviours and sexually transmitted infections (STIs) and associated risk factors in Taiwanese high school students. Students in grades 10 and 11 (mean age: 15.9 +/- 0.9; range: 13-20 years) at two schools were recruited. An anonymous online real-time computer-assisted self-interviewing questionnaire was designed to assess demographic factors and sexual behaviours. Urine specimens were tested for genital chlamydial and gonococcal infections. The same survey and screening was conducted one year later on the same group of students. Overall, 670 individual students (993 visits) were enrolled with 323 students in both surveys. Twenty-seven percent had had sexual intercourse, and more than three quarters (79%) of them had engaged in high-risk sexual behaviours. Having friends using drugs increased the odds of practicing high-risk sexual behaviours (odds ratio [OR] 1.99, 95% CI: 1.13 to 3.50). Among 182 sexually active students, 8.8% had chlamydial (female: 12.5%; male: 5.3%) and 1.1% had gonococcal infections. Having sex with someone met on the Internet was the most significant risk factor for acquiring chlamydia (OR 8.14, 95% CI: 2.82 to 23.51). In conclusion, this adolescent population reported high prevalence of high-risk sexual behaviours and had a high prevalence of chlamydia supportive of a potential epidemic of STIs and HIV.

High-level expression in Escherichia coli of enzymatically active Harvey murine sarcoma virus p21ras protein.

The gene for the Harvey murine sarcoma virus (Ha-MuSV) p21ras protein was fused to the amino-terminal portion of the bacteriophage lambda cII gene on the expression vector pJL6. The fusion was such that transcription was controlled by the well-regulated phage lambda pL promoter, and translation initiated in the cII gene continued in frame into the ras gene sequences that code for p21. When the pL promoter was derepressed, the Escherichia coli cells harboring the fusion plasmid synthesized 23,000-dalton protein, which represented more than 10 percent of the total cellular protein. This protein was chimeric and contained 14 residues, which were specified by the vector; these residues were followed by all of the amino acids that make up Ha-MuSV p21ras except for four residues at the amino-terminal end. The protein appears similar to Ha-MuSV p21ras in that it undergoes immunoprecipitation by monoclonal antibodies directed toward that protein, binds guanosine diphosphate, and is capable of autophosphorylation.

Nucleotide sequence of the p21 transforming protein of Harvey murine sarcoma virus.

Harvey murine sarcoma virus is a retrovirus which transforms cells by means of a single virally encoded protein called p21 has. We have determined the nucleotide sequence of 1.0 kilobase in the 5' half of the viral genome which encompasses the has coding sequences and its associated regulatory signals. The nucleotide sequence has identified the amino acid sequence of two additional overlapping polypeptides which share their reading frames and the carboxyl termini with p21 but which contain additional NH2-terminal amino acids.

Metabolic turnover of human c-rasH p21 protein of EJ bladder carcinoma and its normal cellular and viral homologs.

The EJ bladder carcinoma oncogene is activated by a point mutation in the c-rasH proto-oncogene at the 12th amino acid codon. In an attempt to understand the mechanism of oncogenic activation, a comparative study was undertaken to examine the metabolic turnover and subcellular localization of the p21 protein encoded by the EJ oncogene, the viral oncogene, and its normal cellular homolog. Pulse-labeling experiments indicated that both c-ras p21 proteins were synthesized by a very similar pathway, as was observed for the viral p21 protein of Harvey murine sarcoma virus. The pro-p21 proteins were detected in free cytosol, and the processed products were associated with plasma membrane. The intracellular half-life of p21 proteins was determined by pulse-labeling and chasing in the presence of excess unlabeled methionine. Although both p21 proteins of EJ and the normal c-ras genes which are not phosphorylated have a half-life of 20 h, the viral p21 protein of Harvey murine sarcoma virus which includes a phosphorylated form is much more stable in cells, having a half-life of 42 h, apparently due to phosphorylation.

Structural significance of the GTP-binding domain of ras p21 studied by site-directed mutagenesis.

Point mutations of p21 proteins were constructed by oligonucleotide-directed mutagenesis of the v-rasH oncogene, which substituted amino acid residues within the nucleotide-binding consensus sequence, GXG GXGK. When the glycine residue at position 10, 13, or 15 was substituted with valine, the viral rasH product p21 lost its GTP-binding and autokinase activities. Other substitutions at position 33, 51, or 59 did not impair its binding activity. G418-resistant NIH 3T3 cell lines were derived by transfection with constructs obtained by inserting the mutant proviral DNA into the pSV2neo plasmid. Clones with a valine mutation at position 13 or 15 were incapable of transforming cells, while all other mutants with GTP-binding activity were competent. A mutant with a substitution of valine for glycine at position 10 which had lost its ability to bind GTP and its autokinase activity was fully capable of transforming NIH 3T3 cells. These cells grew in soft agar and rapidly formed tumors in nude mice. The p21 of cell lines derived from tumor explants still lacked the autokinase activity. These findings suggest that the glycine-rich consensus sequence is important in controlling p21 activities and that certain mutations may confer to p21 its active conformation without participation of ligand binding.

Biochemical properties of a highly purified v-rasH p21 protein overproduced in Escherichia coli and inhibition of its activities by a monoclonal antibody.

The v-rasH oncogene of Harvey murine sarcoma virus encodes a 21,000-dalton p21 protein which has been expressed at a high level as a fusion protein in Escherichia coli. We have purified the p21 to over 90% in purity without the use of any detergent or protein denaturant. The purified p21 possesses full biochemical activities of GTP/GDP binding, autokinase, and GTPase. Scatchard analysis indicates a single class of binding sites with Kd values of 0.83 X 10(-8)M for GTP and 1.0 X 10(-8)M for GDP. The binding site can be specifically labeled with a [3H]GTP photoaffinity analog, P3-(4-azidoanilido)-5' GTP. To probe for the active center of p21, we used a battery of six monoclonal antibodies to p21 to examine their effects on p21 activities. We found that only one monoclonal antibody, Y13-259, was capable of inhibiting both GTP/GDP binding and autokinase enzymatic activities, suggesting that these p21 activities are related activities conferred by a single active center within the p21 molecule. These observations together with the recent finding that microinjection of the same monoclonal antibody into NIH 3T3 cells specifically blocks p21 in vivo function (Mulcahy et al., Nature [London] 313:241, 1985) strongly suggest that p21 in vitro activities are responsible for its cellular function.

Neutralizing monoclonal antibody against ras oncogene product p21 which impairs guanine nucleotide exchange.

The neutralizing monoclonal antibody Y13-259 severely hampers the nucleotide exchange reaction between p21-bound and exogenous guanine nucleotides but does not interfere with the association of GDP to p21. These results suggest that the nucleotide exchange reaction is critical for p21 function. Interestingly, the v-ras p21 has a much faster dissociation rate than the p21 of the c-ras proto-oncogene.

Markedly elevated levels of an endogenous sarc protein in a hemopoietic precursor cell line.

The src gene product of Harvey murine sarcoma virus is a 21,000-dalton guanine nucleotide-binding protein. We have recently shown that a wide variety of vertebrate cell strains and cell lines express much lower levels of an endogenous p21 immunologically related to the Harvey murine sarcoma virus-coded p21. In this report, we have examined the levels of endogenous p21 in a unique hemopoietic precursor cell line, 416B, which was originally described as a continuous cell line of a hemopoietic stem cell, CFU-S. The currently available 416B cells express markedly elevated levels of endogenous p21. The level of endogenous p21 in the 416B cells is 5- to 10-fold higher than the level of p21 in Harvey murine sarcoma virus-infected cells and more than 100 times higher than the level of endogenous p21 that we have observed in a variety of other fresh or cultured cells. The results indicate that marked regulation of the levels of an endogenous sarc gene product can occur, and speculation about a possible role for endogenous p21 in normal hemopoietic stem cells is discussed.

Biological activity of a K-ras mutant that contains the 12R/59T/116Y mutations.

The 12R/59T/116Y mutations have been shown to confer a dominant negative activity on H-ras oncogene (H-ras 116Y). To determine whether this event is unique for H-ras, we introduced the same mutations into K-ras oncogene. This mutant, K-ras 116Y, suppressed transformed phenotypes induced by overexpression of H-ras proto-oncogene. NIH3T3 cells expressing K-ras 116Y were resistant to transformation by v-fes oncogene. Analysis of chimaeras between H- and K-ras 116Y showed that the C-terminal variable region determines the level of suppressor activity. These results suggest that these mutations are applicable to other GDP/GTP binding proteins.

Interaction of ras oncogene product p21 with guanine nucleotides.

The nucleotide exchange reaction was observed with purified ras oncogene product p21 overproduced in Escherichia coli (Hattori, S. et al. (1985) Mol. Cell Biol. 5, 1449-1455) under various conditions. (NH4)2SO4 increased the rate of dissociation of bound GDP from c-rasH and v-rasH p21. The dissociation kinetics were those of a first order reaction, and there was a linear relationship between the rate constant and the (NH4)2SO4 concentration. At any concentration of (NH4)2SO4, the exchange rate was faster with v-rasH p21 than that with c-rasH p21. EDTA and (NH4)2SO4 synergetically stimulated the dissociation reaction. Nucleotide-free p21 was prepared by gel filtration on Sephadex G-25 in the presence of 5 mM EDTA and 200 mM (NH4)2SO4 at room temperature. The free p21 was quite thermolabile, but the addition of GDP or GTP completely protected p21 from thermal inactivation. The dissociation constants for GDP and GTP were determined with free p21 to be 8.9 and 8.2 nM, respectively, for v-rasH p21, and 1.0 and 2.6 nM for c-rasH p21. In the presence of 200 mM (NH4)2SO4, these dissociation constants increased 3- to 12-fold.

Juvenile fibromatosis of the posterior mediastinum with intraspinal extension.

Chest radiography, CT, and MR imaging were performed in a 3-year-old girl who had posterior mediastinal fibromatosis with transforaminal intraspinal and chest wall extension. Chest radiographs and CT scans showed a slow-growing, noncalcified but locally aggressive left paravertebral mass. The mass was slightly hyperintense relative to muscle on both T1-weighted and fast spin-echo T2-weighted MR images.

Atlantal stenosis: a rare cause of quadriparesis in a child. Case report.

The authors report the case of a 3-year-old boy who suffered from quadriparesis and respiratory distress after failing to execute a somersault properly. Neuroimaging revealed spinal cord contusion with marked spinal canal stenosis at the level of the atlas. No subtle instability, occult fracture, or other congenital abnormalities were confirmed. Spinal cord contusion with marked canal stenosis is rare, and only several adult cases have been reported. Severe stenosis at the level of the atlas may predispose individuals to severe spinal cord contusion, as occurred in our patient after sustaining trivial trauma.

Role of the Ha-ras (RasH) oncogene in mediating progression of the tumor cell phenotype (review).

Recent experimental evidence indicates that the c-Ha-ras (rasH) oncogene may be causally involved in the etiology and evolution of specific human neoplasms. In addition, cultured cells transformed by the rasH oncogene can induce both a tumorigenic and a metastatic phenotype when expressed in appropriate cultured cells. To begin to define the molecular and biochemical mechanism(s) by which the rasH oncogene induce their effects on expression of the transformed state we have employed a cloned rat embryo fibroblast (CREF) cell line. Transformation of CREF cells with wild-type 5 adenovirus (Wt) results in transformed cells which display anchorage-independence and an increased saturation density in monolayer culture, but are non-tumorigenic in both athymic nude mice and syngeneic Fischer rats. In contrast, when CREF cells are transformed with mutant type 5 adenoviruses, such as H5hrl, or the ElA transforming gene from hrl (0-4.5), tumors are induced in both nude mice and syngeneic rats. However, hrl (0-4.5)-transformed CREF cells are not metastatic following intravenous injection into the tail vein of syngeneic rats. Insertion of an activated T24 rasH oncogene or a wild-type v-rasH oncogene into CREF, wt-transformed CREF or hrl (0-4.5)-transformed CREF cells results in acquisition of a metastatic phenotype by these cells. A mutant v-rasH oncogene (mutant 116K), which is defective in GTP binding and the induction of transformation of NIH 3T3 cells, does not induce transformation in CREF cells, but it can progress wt-transformed CREF cells to a tumorigenic-non-metastatic state. Employing this model system which displays well-defined and stable stages in the tumor cell progression lineage, we have analyzed the potential role of changes in the phosphatidylinositol (PI) cycle and phospholipase A2 (PLA2) enzyme activity during progression to a tumorigenic and metastatic phenotype. An increase in PI cycle intermediates (primarily inositol triphosphate; IP3) were observed only in the wt-transformed and hrl (0-4.5)-transformed CREF cell lines transfected with the rasH oncogene. In the case of PLA2, all rasH-transformed CREF cell lines displayed increased activity. In contrast, CREF cells transformed only by Ad5 (Wt or hrl (0-4.5)) or the 116K v-rasH oncogene did not display increased PLA2 activity similar to that observed in rasH transfected cells. Since one important metabolite generated by PLA2 is arachidonic acid, which is converted into prostaglandins and leukotrienes by cyclooxygenase or lipooxygenase, respectively, the levels of prostaglandin E2 (PGE2) in the various cell lines were monitored.(ABSTRACT TRUNCATED AT 400 WORDS)

Mediastinal lipoblastoma with intraspinal extension: MRI demonstration.

Lipoblastomatous lesions are mesenchymal tumors of embryonal white fat and are classified into two forms: a superficial, well-defined mass (lipoblastoma) or a deep, infiltrative lesion (lipoblastomatosis). We report an unique case of mediastinal lipoblastoma in a 17-month-old boy which harbored a dual nature and exhibited the characteristics of both forms, a large well-encapsulated intrathoracic main tumor with focal infiltrative features at the thoracic inlet and transforaminal intraspinal extension forming a long-segment extradural mass. In addition to specific signal characterization of a fatty mediastinal mass with intratumoral streaks and whorls corresponding to the fibrovascular network, magnetic resonance (MR) imaging offered clear demonstration of the chest wall, lower neck and intraspinal extension, which was important for preoperative planning.

Fibrosis of the omohyoid muscle--an unusual cause of torticollis.

An 11-year-old boy had a left neck mass with torticollis. On exploration, a fibrotic mass in the superior belly of the left omohyoid muscle was found, which shortened the muscle and pulled the hyoid bone downward. Resection of the fibrotic muscle was performed. The patient recovered well after the operation with resolution of his torticollis.

A case of demyelinating disease with clinical and radiological features mimicking cerebral tumor.

Demyelinating disease may present with clinical and radiological features mimicking brain tumor. A 43-year-old man was admitted because of progressive right hemiparesis, facial weakness and dysarthria. Computed tomographic scans revealed two expansive lesions in the left frontal lobe and midbrain, respectively. A brain tumor or metastatic lesion was suspected. The patient underwent left frontal craniotomy and the surgical biopsy revealed a demyelinating process. The patient, however, had a poor response to steroid treatment and died two months later. The possible nature of demyelinating disease in this case is discussed.

Magnetic resonance imaging of radiation necrosis after radiotherapy for acromegaly: report of a case.

A total 5,600 cGy in 28 fractions in 44 days was delivered to a 53-year-old woman with acromegaly after transsphenoid removal of a pituitary adenoma. Sixteen months later, she suffered a progressive loss of vision. Radiation optic neuropathy was diagnosed. A T1-weighted imaging showed gadolinium-enhanced lesions in the optic chiasm, pituitary stalk and hypothalamus. Magnetic resonance imaging is uniquely suited to detect radiation injury to the sellar region. The complications of radiation therapy for benign tumor can be severe even by current standard procedures.

Posterior cerebral artery aneurysm in a two-year-old girl.

Intracranial aneurysms are seldom encountered in the pediatric age group, and those within the posterior circulation are even more rare. Intracranial aneurysms in children differ from adult aneurysms in size, distribution, histology and incidence of symptoms. The authors report a 2-year-old female patient with a posterior cerebral artery aneurysm presenting with seizures, right third nerve palsy and right hemiparesis caused by compression of the contralateral cerebral peduncle. The patient underwent a pterional craniotomy and clipping of the aneurysm. Right oculomotor nerve palsy remained postoperatively. We review the literature and discuss the characteristics of aneurysms of the posterior cerebral artery and those in early childhood.