Structures of Fission Yeast Inositol Pyrophosphate Kinase Asp1 in Ligand-Free, Substrate-Bound, and Product-Bound States

Expression of the fission yeast Schizosaccharomyces pombe phosphate regulon is sensitive to the intracellular level of the inositol pyrophosphate signaling molecule 1,5-IP8. IP8 dynamics are determined by Asp1, a bifunctional enzyme consisting of an N-terminal kinase domain and a C-terminal pyrophosphatase domain that catalyze IP8 synthesis and catabolism, respectively. Here, we report structures of the Asp1 kinase domain, crystallized with two protomers in the asymmetric unit, one of which was complexed with ligands (ADPNP, ADP, or ATP; Mg2+ or Mn2+; IP6, 5-IP7, or 1,5-IP8) and the other which was ligand-free. The ligand-free enzyme adopts an "open" conformation that allows ingress of substrates and egress of products. ADPNP, ADP, and ATP and associated metal ions occupy a deep phospho-donor pocket in the active site. IP6 or 5-IP7 engagement above the nucleotide favors adoption of a "closed" conformation, in which surface protein segments undergo movement and a disordered-to-ordered transition to form an inositol polyphosphate-binding site. In a structure mimetic of the kinase Michaelis complex, the anionic 5-IP7 phosphates are encaged by an ensemble of nine cationic amino acids: Lys43, Arg223, Lys224, Lys260, Arg274, Arg285, Lys290, Arg293, and Lys341. Alanine mutagenesis of amino acids that contact the adenosine nucleoside of the ATP donor underscored the contributions of Asp258 interaction with the ribose 3'-OH and of Glu248 with adenine-N6. Changing Glu248 to Gln elicited a gain of function whereby the kinase became adept at using GTP as phosphate donor. Wild-type Asp1 kinase can utilize N6-benzyl-ATP as phosphate donor. IMPORTANCE The inositol pyrophosphate signaling molecule 1,5-IP8 modulates fission yeast phosphate homeostasis via its action as an agonist of RNA 3'-processing and transcription termination. Cellular IP8 levels are determined by Asp1, a bifunctional enzyme composed of an N-terminal kinase and a C-terminal pyrophosphatase domain. Here, we present a series of crystal structures of the Asp1 kinase domain, in a ligand-free state and in complexes with nucleotides ADPNP, ADP, and ATP, divalent cations magnesium and manganese, and inositol polyphosphates IP6, 5-IP7, and 1,5-IP8. Substrate binding elicits a switch from open to closed conformations, entailing a disordered-to-ordered transition and a rearrangement or movement of two peptide segments that form a binding site for the phospho-acceptor. Our structures, along with structure-guided mutagenesis, fortify understanding of the mechanism and substrate specificity of Asp1 kinase, and they extend and complement structural and functional studies of the orthologous human kinase PPIP5K2.

Structure-function analysis of fission yeast cleavage and polyadenylation factor (CPF) subunit Ppn1 and its interactions with Dis2 and Swd22

Fission yeast Cleavage and Polyadenylation Factor (CPF), a 13-subunit complex, executes the cotranscriptional 3' processing of RNA polymerase II (Pol2) transcripts that precedes transcription termination. The three-subunit DPS sub-complex of CPF, consisting of a PP1-type phosphoprotein phosphatase Dis2, a WD-repeat protein Swd22, and a putative phosphatase regulatory factor Ppn1, associates with the CPF core to form the holo-CPF assembly. Here we probed the functional, physical, and genetic interactions of DPS by focusing on the Ppn1 subunit, which mediates association of DPS with the core. Transcriptional profiling by RNA-seq defined limited but highly concordant sets of protein-coding genes that were dysregulated in ppn1Δ, swd22Δ and dis2Δ cells, which included the DPSΔ down-regulated phosphate homeostasis genes pho1 and pho84 that are controlled by lncRNA-mediated transcriptional interference. Essential and inessential modules of the 710-aa Ppn1 protein were defined by testing the effects of Ppn1 truncations in multiple genetic backgrounds in which Ppn1 is required for growth. An N-terminal 172-aa disordered region was dispensable and its deletion alleviated hypomorphic phenotypes caused by deleting C-terminal aa 640-710. A TFIIS-like domain (aa 173-330) was not required for viability but was important for Ppn1 activity in phosphate homeostasis. Distinct sites within Ppn1 for binding to Dis2 (spanning Ppn1 aa 506 to 532) and Swd22 (from Ppn1 aa 533 to 578) were demarcated by yeast two-hybrid assays. Dis2 interaction-defective missense mutants of full-length Ppn1 (that retained Swd22 interaction) were employed to show that binding to Dis2 (or its paralog Sds21) was necessary for Ppn1 biological activity. Ppn1 function was severely compromised by missense mutations that selectively affected its binding to Swd22.

Distinct Cdk9-phosphatase switches act at the beginning and end of elongation by RNA polymerase II

Reversible phosphorylation of Pol II and accessory factors helps order the transcription cycle. Here, we define two kinase-phosphatase switches that operate at different points in human transcription. Cdk9/cyclin T1 (P-TEFb) catalyzes inhibitory phosphorylation of PP1 and PP4 complexes that localize to 3′ and 5′ ends of genes, respectively, and have overlapping but distinct specificities for Cdk9-dependent phosphorylations of Spt5, a factor instrumental in promoter-proximal pausing and elongation-rate control. PP1 dephosphorylates an Spt5 carboxy-terminal repeat (CTR), but not Spt5-Ser666, a site between Kyrpides-Ouzounis-Woese (KOW) motifs 4 and 5, whereas PP4 can target both sites. In vivo, Spt5-CTR phosphorylation decreases as transcription complexes pass the cleavage and polyadenylation signal (CPS) and increases upon PP1 depletion, consistent with a PP1 function in termination first uncovered in yeast. Depletion of PP4-complex subunits increases phosphorylation of both Ser666 and the CTR, and promotes redistribution of promoter-proximally paused Pol II into gene bodies. These results suggest that switches comprising Cdk9 and either PP4 or PP1 govern pause release and the elongation-termination transition, respectively.

Cdk9 (P-TEFb) and its substrate Spt5 influence events throughout the transcription cycle. Here, the authors define two switches with the potential to regulate promoter-proximal pause release and termination, respectively containing phosphatases PP4 and PP1, which are both inhibited by Cdk9, but have different specificities for sites on Spt5 and occupy opposite ends of genes.

A Cdk9-PP1 switch regulates the elongation-termination transition of RNA polymerase II

The end of the RNA polymerase II (Pol II) transcription cycle is strictly regulated to prevent interference between neighbouring genes and to safeguard transcriptome integrity ¹ . The accumulation of Pol II downstream of the cleavage and polyadenylation signal can facilitate the recruitment of factors involved in mRNA 3'-end formation and termination ² , but how this sequence is initiated remains unclear. In a chemical-genetic screen, human protein phosphatase 1 (PP1) isoforms were identified as substrates of positive transcription elongation factor b (P-TEFb), also known as the cyclin-dependent kinase 9 (Cdk9)-cyclin T1 (CycT1) complex ³ . Here we show that Cdk9 and PP1 govern phosphorylation of the conserved elongation factor Spt5 in the fission yeast Schizosaccharomyces pombe. Cdk9 phosphorylates both Spt5 and a negative regulatory site on the PP1 isoform Dis2 ⁴ . Sites targeted by Cdk9 in the Spt5 carboxy-terminal domain can be dephosphorylated by Dis2 in vitro, and dis2 mutations retard Spt5 dephosphorylation after inhibition of Cdk9 in vivo. Chromatin immunoprecipitation and sequencing analysis indicates that Spt5 is dephosphorylated as transcription complexes traverse the cleavage and polyadenylation signal, concomitant with the accumulation of Pol II phosphorylated at residue Ser2 of the carboxy-terminal domain consensus heptad repeat ⁵ . A conditionally lethal Dis2-inactivating mutation attenuates the drop in Spt5 phosphorylation on chromatin, promotes transcription beyond the normal termination zone (as detected by precision run-on transcription and sequencing ⁶ ) and is genetically suppressed by the ablation of Cdk9 target sites in Spt5. These results suggest that the transition of Pol II from elongation to termination coincides with a Dis2-dependent reversal of Cdk9 signalling-a switch that is analogous to a Cdk1-PP1 circuit that controls mitotic progression ⁴ .

Gene-specific mechanisms direct glucocorticoid-receptor-driven repression of inflammatory response genes in macrophages

The glucocorticoid receptor (GR) potently represses macrophage-elicited inflammation, however, the underlying mechanisms remain obscure. Our genome-wide analysis in mouse macrophages reveals that pro-inflammatory paused genes, activated via global negative elongation factor (NELF) dissociation and RNA Polymerase (Pol)2 release from early elongation arrest, and non-paused genes, induced by de novo Pol2 recruitment, are equally susceptible to acute glucocorticoid repression. Moreover, in both cases the dominant mechanism involves rapid GR tethering to p65 at NF-kB-binding sites. Yet, specifically at paused genes, GR activation triggers widespread promoter accumulation of NELF, with myeloid cell-specific NELF deletion conferring glucocorticoid resistance. Conversely, at non-paused genes, GR attenuates the recruitment of p300 and histone acetylation, leading to a failure to assemble BRD4 and Mediator at promoters and enhancers, ultimately blocking Pol2 initiation. Thus, GR displays no preference for a specific pro-inflammatory gene class; however, it effects repression by targeting distinct temporal events and components of transcriptional machinery.

A functional comparison of medial pivot and condylar knee designs based on patient outcomes and parameters of gait

Aims

The outcome of total knee arthroplasty (TKA) is not always satisfactory. The purpose of this study was to identify satisfaction and biomechanical features characterising the gait of patients who had undergone TKA with either an anatomical single radius design or a medial pivot design. We hypothesised that the latter would provide superior function.

Patients and Methods

This is a study of a subset of patients recruited into a prospective randomised study of a single radius design versus a medial pivot design, with a minimum follow-up of one year. Outcome measurements included clinical scores (Knee Society Score (KSS) and Oxford Knee Score (OKS)) and gait analysis using an instrumented treadmill.

Results

There was no statistically significant difference between the two groups for both the KSS and OKS. There was also no statistical significance in cadence, walking speed, stride length and stance time, peak stride, mid support and push-off forces.

Conclusion

This study corroborates a previous study by the same authors that showed equally good results in clinical outcome and gait between the conventional single radius and medial pivot designs under stringent testing conditions.

Cite this article: Bone Joint J 2018;(1 Supple A)100-B:76–82.

ppGpp couples transcription to DNA repair in E. coli

The small molecule alarmone (p)ppGpp mediates bacterial adaptation to nutrient deprivation by altering the initiation properties of RNA polymerase (RNAP). ppGpp is generated in Escherichia coli by two related enzymes, RelA and SpoT. We show that ppGpp is robustly, but transiently, induced in response to DNA damage and is required for efficient nucleotide excision DNA repair (NER). This explains why relA-spoT-deficient cells are sensitive to diverse genotoxic agents and ultraviolet radiation, whereas ppGpp induction renders them more resistant to such challenges. The mechanism of DNA protection by ppGpp involves promotion of UvrD-mediated RNAP backtracking. By rendering RNAP backtracking-prone, ppGpp couples transcription to DNA repair and prompts transitions between repair and recovery states.

HER2+ circulating tumor cells (CTCs): a more sensitive and specific marker for CTCs positivity than total CTCs count in early breast cancer

Abstract #5023

Background: CTCs have been detected using the CellSearch System in early and metastatic breast cancer (BC). However, no studies have been reported for the detection of HER2+ CTCs using the CellSearch System. In this study we aimed to analyze CTCs for HER2 expression in different stages of BC progression from ductal/lobular carcinoma in situ (DCIS/LCIS) to early and metastatic BC. Patients and Methods: 20ml of peripheral blood per woman was analyzed from healthy women, DCIS/LCIS or early BC patients, whereas 7.5ml of blood was analyzed from metastatic BC patients. The presence of CTCs as well as HER2 expression was assessed with the CellSearchSystem (Veridex, USA). After immunomagnetic enrichment with an anti-Epcam-antibody, cells were labeled with anti-cytokeratin (8,18,19), anti-HER2 and anti-CD45 antibodies. CTCs were defined as Cytokeratin-positive/CD45-negative cells, whereas HER2+ CTCs were defined as Cytokeratin-positive/CD45-negative/HER2-positive cells. Results: The presence of CTCs and HER2+ CTCs in healthy women, DCIS/LCIS, early and metastatic BC is depicted in table.
 
 Since 1 and 2 CTCs were detected in 7 (14.8%) and 4 (8.5%) of 47 healthy women, respectively, >1CTC or >2CTCs were selected as cutoffs for further analysis. Using the above cutoffs, 7 (18.9%) and 5 (13.5%) of 37 patients with early BC were considered CTC-positive, respectively. Since no HER2+ CTCs were detected in any of the 47 healthy women, a cutoff of ≥1 HER2+ CTCs was chosen. With this cutoff, more women with early BC [11 (29.7%) of 37 women] were considered CTC-positive. Conclusion: HER2+ CTCs seems to be a more sensitive and specific marker for CTCs' positivity than total CTCs counts in early breast cancer. Clinical relevance of the above cutoff for CTCs positivity using HER2+ CTCs detection will be performed in ongoing clinical trials of HER2 positive early breast cancer.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5023.

The possible significance of Clostridium spp. in blood cultures

The significance of Clostridium spp. in blood cultures was evaluated by two methods. In the first part of the study, a group of 80 patients with Clostridium spp. bacteraemia was compared with a group of 100 patients with Bacillus spp. in blood cultures, making the assumption that Bacillus almost invariably represents contamination (pseudobacteraemia). Significant differences were found between the two groups, suggesting that growth of Clostridium did not represent pseudobacteraemia. Patients with Clostridium bacteraemia were older, had a higher frequency of gastrointestinal disease (especially colorectal tumours), were associated more frequently with polymicrobial bacteraemia, and had a higher mortality rate. In the second part of the study, each of the 80 cases of Clostridium bacteraemia was evaluated individually for clinical relevance by an infectious diseases expert. In two-thirds of the cases, isolates of Clostridium from blood were considered to be of clinical relevance, whereas in one-third of cases, the clinical significance of this finding was doubtful. It was concluded that growth of Clostridium spp. in blood cultures, even in the absence of one of the histotoxic syndromes, is often of clinical significance, and that such findings should be properly evaluated and not ignored.

Comparative analyses of multi-species sequences from targeted genomic regions

The systematic comparison of genomic sequences from different organisms represents a central focus of contemporary genome analysis. Comparative analyses of vertebrate sequences can identify coding and conserved non-coding regions, including regulatory elements, and provide insight into the forces that have rendered modern-day genomes. As a complement to whole-genome sequencing efforts, we are sequencing and comparing targeted genomic regions in multiple, evolutionarily diverse vertebrates. Here we report the generation and analysis of over 12 megabases (Mb) of sequence from 12 species, all derived from the genomic region orthologous to a segment of about 1.8 Mb on human chromosome 7 containing ten genes, including the gene mutated in cystic fibrosis. These sequences show conservation reflecting both functional constraints and the neutral mutational events that shaped this genomic region. In particular, we identify substantial numbers of conserved non-coding segments beyond those previously identified experimentally, most of which are not detectable by pair-wise sequence comparisons alone. Analysis of transposable element insertions highlights the variation in genome dynamics among these species and confirms the placement of rodents as a sister group to the primates.

Pediatric laryngoscopes: design and application

Examination of the upper aerodigestive tract for diagnosis and treatment has become more important in pediatric otolaryngology. Techniques of endoscopy have improved, anesthesia is safer, and there are many specialized laryngoscopes designed specifically for the small, sensitive airways of infants and children. Knowledge of the design advantages, specifications, and applications, including the use of telescopes and the operating microscope, will assist in selection of the appropriate laryngoscope for optimum exposure.

Photography of severe laryngeal obstruction

Thirty-five-millimeter photography using rigid rod lens telescopes at direct laryngoscopy is the most versatile and reliable method of laryngeal documentation. Photography of severe laryngeal obstruction, whether in pediatric or adult patients, mandates a method of anesthesia chosen for maximum patient safety, a laryngoscope selected for optimal exposure, confidence in controlling the airway, and a technique that does not jeopardize the safety of the patient.

Anesthesia for pediatric airway endoscopy

Anesthesia for endoscopic assessment and treatment of airway problems in infants and children requires a systematic and thoughtful approach. The anesthesiologist and otolaryngologist should have a sound knowledge of the causes of airway obstruction. The anesthesiologist must be aware of the instrumentation likely to be used and the endoscopist must be well informed about the principles of anesthesia. The choice of technique depends upon the needs for each patient, but in most cases, the safest and most controlled method is a gaseous induction with assisted spontaneous respiration and continued maintenance by the inhalational method, supplemented by topically applied local anesthesia.

Obstructive suprastomal granulation tissue following percutaneous tracheostomy

Percutaneous dilatational tracheostomy is frequently performed as an alternative to traditional surgical open tracheostomy with many reported benefits. Despite its relative safety and widespread acceptance, complications can be associated with the procedure itself or long-term. We present four cases where there was difficulty with decannulation because of exuberant obstructive granulation tissue. In each case, the percutaneous tracheostomy involved the cricoid cartilage.

Recurrent laryngeal nerve injury caused by a laryngeal mask airway

Although there have been few reports of serious complications with the laryngeal mask airway, we record a case of permanent unilateral vocal cord paralysis following the use of a laryngeal mask airway and review the literature describing injuries, not only to the recurrent laryngeal nerves but also to the hypoglossal and lingual nerves.

[Legionellosis in Israel--a view of the situation]

Infection with Legionella remains an important cause of disease and death. We analyzed our laboratory data from 1993 through 1997, augmented by our 20 years of experience. The incidence of Legionella as a cause of pneumonia varied in our study from 5%-9%, with a slight increase during the winter. Isolation of these microorganisms from different water sources was higher during the summer and ranged from 7%-70%. Special laboratory tests are necessary to diagnose the disease and monitor these bacteria in water samples. The serologic method--indirect immunofluorescent assay--for 41 serogroups of Legionella was the main diagnostic method used. Legionella sg. 1 was the most frequent cause of the disease, with an incidence of 52% in 1993, decreasing to 15% in 1997. An increase in the incidence of seropositivity to "other Legionellae" is characteristic for our country. No correlation was found between the incidence of isolation of a specific strain and exposure. However, it is well known that the disease is overtreated but underdiagnosed, which requires reversal. Larger studies of Legionella colonization in water supplies and in air are needed in order to establish the risk of infection. Water sources are presently under-studied, as are respiratory devices in hospitals, or they are not studied at all in Israel, such as in mist machines in supermarkets, in dental clinics, and in ships and airplanes.

Psychosocial stressors among sheltered homeless children: relationship to behavior problems and depressive symptoms

Level of exposure to severe psychosocial stressors was assessed among homeless children in emergency family shelters in an urban locale. The relationship between such exposure and child mental health problems was then investigated, along with the effects of adult family social support. Implications of the findings are discussed.

Thirty-five-millimeter photography using the Kantor-Berci video laryngoscope

The Kantor-Berci model II laryngoscopes employ a centrally located rigid telescope. Although the primary application is for video laryngoscopy, the system can also be used for 35-mm photography during microlaryngeal operations. The fixed, unchangeable field of view and the great depth of focus make this system ideal for photographic documentation during endolaryngeal surgery without interruption of the procedure.

Acute rheumatic fever in southern Saudi Arabia

Forty six attacks of acute rheumatic fever (ARF) in forty patients were diagnosed between November 1987 and August 1995. Thirty four were initial attacks and 12 were recurrences. Arthritis was the commonest feature, 84.8%. Carditis occurred in 65.2% of the group, 67.6% of the initial attacks and 58.3% of the recurrences; however, the frequency of moderate/severe carditis was higher in recurrences, 25% versus 11.8%. Of those with carditis, mitral regurgitation occurred in 93.3%, aortic regurgitation in 16.7% and significant tricuspid regurgitation in 6.7%. Mitral stenosis was not encountered. No mortality occurred during ARF. Chorea, erythema marginatum and subcutaneous nodules were infrequent. These data are similar with those from a previous study which demonstrated the mild nature of ARF in Saudi Arabia, but showed higher frequency of carditis and suggested the frequency of carditis was not significantly higher during recurrences as compared to frequency of moderate/severe carditis.

Indirect laryngeal photography using rigid telescopes

A technique for indirect laryngeal color photography for the office or clinic using rigid rod-lens angled telescopes is outlined. The photographic equipment can be used for documentation at both direct and indirect laryngoscopy except that the latter requires purpose-designed 70 degrees or 90 degrees telescopes. The method, which requires practice and patience, and the equipment are described in detail, and the difficulties and frustrations that are encountered are discussed.

Idiopathic subglottic stenosis: diagnosis and endoscopic laser treatment

The records of 15 patients with idiopathic subglottic stenosis treated at Royal North Shore Hospital, Sydney, between 1980 and 1994 were reviewed. All were female and had similar characteristic clinical and histopathologic features. Endoscopic laser vaporization was the primary treatment in 12 patients and was successful in maintaining the airway of 8 of these 12; this outcome indicates that the disease can be managed, at least initially, by endoscopic laser treatment in most cases.

Airway management in acute infectious croup syndromes

The article presents the author's experience with airway management of 500 children with acute infectious croup and epiglottitis over a 7-year period in a teaching hospital setup. A policy of early elective protective intubation under controlled condition for children with severe croup and epiglottitis, in a multidisciplinary intensive care setting resulted in a satisfactory outcome. Recent developments in the field are discussed; these include non-invasive monitoring, medical treatment options for viral croup with parenteral high dose dexamethasone and nebulized adrenaline, newer broad-spectrum antimicrobials for drug-resistant bacterial infectious and an effective vaccine against Hemophilus influenzae type b. These hold the promise of reducing morbidity and mortality from acute infectious croup syndromes even in situations with limited surgical and monitoring facilities.

Renal agenesis and ureteropelvic junction obstruction in an infant with Turner syndrome

An infant who had Turner syndrome with left renal agenesis and right hydronephrosis due to functional ureteropelvic junction obstruction is reported. The importance of routine imaging for early identification of potentially serious renal anomalies in patients being evaluated for short stature and possible Turner syndrome is emphasized.

Sheltered homeless children: their eligibility and unmet need for special education evaluations

OBJECTIVES

This study described the proportion of sheltered homeless children in Los Angeles, Calif, who were eligible for special education evaluations because of a probable behavioral disorder, learning disability, or mental retardation, and to explore their level of unmet need for special education services.

METHODS

This was a cross-sectional study of 118 parents and 169 children aged 6 through 12 years living in 18 emergency homeless family shelters in Los Angeles County, California. Parents and children were interviewed with standardized mental health and academic skill measures in English and Spanish.

RESULTS

Almost half (45%) of the children met criteria for a special education evaluation, yet less than one quarter (22%) had ever received special education testing or placement. The main point of contact for children with behavioral disorders and learning problems was the general health care sector.

CONCLUSIONS

School-aged sheltered homeless children have a high level of unmet need for special education evaluations, the first step toward accessing special education programs. Interventions for homeless children should include integration of services across special education, general health care, and housing service sectors.

Hypoplasia of the epiglottis: case report and review

We report an infant born with a hypoplastic epiglottis and present the first in vivo photograph of the condition. Absence or hypoplasia of the epiglottis is a rare anomaly. Previously reported cases either died shortly after birth due to multiple congenital anomalies or details of the outcome were lacking. The clinical effects of hypoplastic epiglottis are discussed.

Effects of gender on listeners' judgments of speech intelligibility

Effects of gender on listeners' judgments of intelligibility were investigated. Subjects (15 women; 15 men) provided magnitude-estimation scaling responses and over-all impression of the intelligibility of a male and female speaker's comparable versions of audiotaped speech samples varying systematically in terms of the number of phonemes produced correctly. There was no significant difference between male and female subjects' magnitude-estimation scaling responses; however, their over-all impressions of the intelligibility of the speakers tended to differ. Women indicated that the male speaker was more understandable, and men indicated that the female speaker was more understandable. Magnitude-estimation scaling may provide an objective means for evaluating a speaker's intelligibility. It appears to transcend gender-biases associated with judgments of speech intelligibility.

Death following elective tracheostomy decannulation in chronic neonatal lung disease

Widespread air leak as a fatal complication of elective tracheostomy decannulation in a child aged 20 months with chronic neonatal lung disease (CNLD) is reported. We discuss likely mechanisms for the development of air leak following tracheostomy tube removal in young children with obstructive airways disease and suggest that this procedure be performed in an intensive care or high dependency unit.

Gastric outlet obstruction caused by prepyloric web in a case of Down's syndrome

The authors describe an infant with Down's syndrome who had a prepyloric web complicated by severe gastric outlet obstruction. The delay in diagnosis was responsible for malnutrition and the early postoperative complications of hypothermia and hypoglycemia. Awareness of the association of gastrointestinal abnormalities with Down's syndrome will enable appropriate evaluation for early diagnosis of this surgically correctable malformation.

Mental health problems among homeless mothers: relationship to service use and child mental health problems

BACKGROUND

The purpose of this study was to describe the prevalence of psychological distress and probable lifetime mental disorders among homeless mothers, their use of services, and the relationship between maternal and child mental health problems.

METHOD

The study involved a cross-sectional assessment of 110 mothers and 157 children living in homeless shelters in Los Angeles County.

RESULTS

The majority (72%) of sheltered homeless mothers reported high current psychological distress or symptoms of a probable lifetime major mental illness or substance abuse. However, few mothers (15%) in need of services received mental health care, and the main point of contact for those with a mental health problem was the general medical sector. Mothers with a probable mental disorder were also significantly more likely to have children with either depression or behavior problems.

CONCLUSIONS

Homeless mothers have a high level of unmet need for mental health services. The relationship between maternal and child problems underscores the need for homeless family interventions that promote access to psychiatric care for both generations.

Objective life circumstances and life satisfaction: results from the course of homelessness study

Relations between objective life circumstances and life satisfaction were examined using structural equation modeling of two waves of data obtained from homeless and mentally ill homeless participants (N = 298) in the Course of Homelessness Study (COH). Cross-sectional analyses revealed that objective indexes of life quality were primarily associated with domain-specific, rather than general, life satisfaction. Results could not be attributed to the covariation of life satisfaction with other indexes of subjective well-being (i.e., psychological symptoms and perceived self-mastery). In addition, significant direct ("causal") cross-lagged effects were found linking initial objective housing status with subsequent income and subsequent satisfaction with housing. By contrast, neither life satisfaction nor any other index of subjective well-being exerted a direct impact on subsequent life quality as assessed by objective indexes. Finally, we found no support for previous claims that perceived self-mastery mediates the impact of objective life circumstances on subsequent life satisfaction. Findings are discussed with reference to the utility of a hierarchical model of life satisfaction that incorporates domain-specific, as well as global, satisfaction.

Subglottic ductal cysts in the preterm infant: association with laryngeal intubation trauma

Acquired subglottic ductal cysts following prolonged intubation in preterm infants have been reported with increasing frequency during the past two decades. This paper reviews the subglottic ductal cysts diagnosed in 15 pediatric patients between 1989 and 1993--the largest such review. Eighty percent were observed in preterm low-birth weight infants following prolonged intubation, and all but 3 of the patients had major intubation trauma of the larynx--an association not previously reported. The cysts were usually multiple and arose in the posterolateral subglottis. Most were small and did not cause significant airway obstruction, but associated intubation changes were sufficiently severe to necessitate tracheotomy in 10 patients. The cysts observed in our study did not enlarge and in 4 patients were observed to spontaneously resolve or shrink in size--trends not previously reported. Subglottic ductal cysts noted in preterm infants after prolonged intubation most commonly occur in association with laryngeal intubation trauma and are likely a component of intubation trauma. Although these cysts may resolve without therapy, careful follow-up and treatment of potentially obstructing subglottic ductal cysts is recommended.

Effects of Medicare's prospective payment system on service use by depressed elderly inpatients

OBJECTIVE

To determine the effects of Medicare's prospective payment system (PPS) on hospital care, changes in length of stay and intensity of clinical services received by 2,746 depressed elderly patients in 297 acute care general medical hospitals were studied.

METHODS

A pre-post design was used, and differences in sickness at admission were controlled for. Data on length of stay and use of specific clinical services were obtained from the medical record using a medical record abstraction form. Care provided on units exempt from PPS was compared with care provided in nonexempt units.

RESULTS

After implementation of PPS, the average length of stay fell by up to three days within the different types of acute care settings studied, but this decline was partially offset by proportionately more admissions to psychiatric units, which had longer lengths of stay. Intensity of clinical services increased after PPS implementation, especially in nonexempt psychiatric units.

CONCLUSION

Despite financial incentives for hospitals to reduce clinical services under PPS, its implementation was not associated with a marked decline in length of stay, when averaged across all treatment settings, and was associated with an increase in the intensity of many clinical services used by depressed elderly patients in general hospitals.

Heterotopic bone formation affecting the hip joint is preventable in high risk patients by post-operative radiation

Between 1984 and 1993, 40 high risk patients (45 hips) received postoperative irradiation as prophylaxis against heterotopic ossification (HO). Radiotherapy was commenced within 5 days of the surgery in 43 of 45 hips. The development of HO was assessed by comparison of radiographic films prior to irradiation and at least 2 months after treatment (median interval 12 months). Progression of HO was observed in only two of 45 hips (4.3%) and of clinical significance in one (2.2%). Treatment was well tolerated with no acute complications or loosening of prosthetic components attributable to irradiation. During the study period, the treatment programme changed from 20 Gy in 10 fractions to 6-8 Gy in a single fraction, without loss of treatment efficacy. As well as improving resource utilization, single fraction techniques allow fewer patient transfers thereby reducing patient discomfort and risk of hip dislocation. This procedure is uncomplicated and should be considered more widely in the management of this disabling non-malignant condition.