One-stage revision hip arthroplasty for infection using primary cementless stems as first-line implants: About 35 cases

INTRODUCTION

During infected total hip arthroplasty revisions (THAR), the need for systematic antibiotic cementation remains undefined.

HYPOTHESIS

Implantation of a primary cementless stem as first-line implant in 1-stage septic THAR provides results as good as those from a stem cemented with antibiotics in terms of infection resolution.

MATERIALS AND METHODS

We retrospectively examined 35 patients operated on for septic THAR with Avenir® cementless stem placement - between 2008 and 2018 at Besançon University Hospital - with a minimum follow-up of 2 years to define healing in the absence of infectious recurrence. Clinical outcomes were assessed using the Harris, Oxford, and Merle D'Aubigné scores. Osseointegration was analyzed by the Engh radiographic score.

RESULTS

The median follow-up was 5±2.6 years (2-11). The infection was cured in 32 of 35 (91.4%) patients. The median scores of the following were: Harris 77/100, Oxford 47.5/60 and Merle d'Aubigné 15/18. Of 32 femoral stems, 31 (96.8%) had radiographically stable osseointegration. Age greater than 80 years was a risk factor for failure to cure the infection during septic THAR.

DISCUSSION

A primary cementless stem as first-line implant plays a role in 1-stage septic THAR. It confers good results in terms of infection resolution and stem integration in the setting of loss of femoral bone substances rated Paprosky 1.

LEVEL OF EVIDENCE

IV; retrospective case series.

Osteosynthesis of periprosthetic type A and B femoral fractures using an unlocked plate with integrated cerclage cable and trochanteric hook: A multicenter retrospective study of 45 patients with mean follow-up of 20 months

INTRODUCTION

Femoral periprosthetic fracture (FPF) is a frequent complication in dependent elderly persons, with a limited life expectancy. Their management is difficult and the choice between osteosynthesis and prosthesis is still matter of discussion. To date, there is no study on unlocked plate with integrated cerclage cable and trochanteric hook for this indication. The objectives of this study were to analyze fracture healing, complication rate and functional outcome. Our hypothesis is that this technique allows a high rate of consolidation and a return to the previous state in terms of autonomy and place of residence.

MATERIALS AND METHODS

We conducted a retrospective multicenter study between 2010 and 2015. The inclusion criteria were: patients with type A and B FPF according to the classification of Vancouver who received osteosynthesis hook plate. The evaluation focused on the consolidation period, complications and pre and postoperative Parker and Katz scores. Death, nonunion, dislocation, infection and failure of fixation were considered major complications.

RESULTS

Forty-five patients met the inclusion criteria and were evaluated at mean 20 months (6-72). All fractures consolidated at a mean 7 weeks (6-10), except one that has not undergone further surgery in the absence of functional impairment. Parker score decreased from 6.4 to 4.9 (p=0.03) and Katz score from 4.8 to 4.3 (p=0.045). Five patients died within the year of the operation. Five patients living at home preoperatively were admitted to an institution, the others returned to their retirement home or nursing home.

CONCLUSION

This plate allows for a quick and effective management of patients with FPF. The low rate of complications and the very good consolidation rate lead us to use the same plate even for class B2 or B3 fractures in some patients with precarious health condition who cannot tolerate major revision surgery: Elderly, ASA score >3, loss of autonomy, Katz score <4.

Is amputation a viable treatment option in lower extremity trauma?

INTRODUCTION

There is currently no consensus on how to treat patients with lower extremity trauma. Should amputation be performed early on to avoid complications or should the limb be saved at any price? The goal of this study was to show that early amputation is a viable treatment option in lower extremity trauma cases.

MATERIAL AND METHODS

Twenty patients who underwent early amputation and 16 patients who underwent limb-salvage were included with a minimum follow-up of 1year. The main endpoints were the Mangled Extremity Severity Score (MESS) used to predict amputation, complications, sequelae, bone union and functional outcomes.

RESULTS

The amputees had a higher MESS score than those treated conservatively (7.8 vs. 4.9, P<0.00001), had a shorter hospital stay (P<0.022) and had fewer postoperative complications (P<0.003), especially infection-related (P<0.001). The prevalence of infection in limb-salvage patients was 61%. There was no significant difference between the two groups in terms of quality of life.

DISCUSSION

In cases of lower extremity trauma, early amputation and limb-sparing treatment each have their advantages and disadvantages. Early amputation seems to be better in cases of complications, despite similar quality of life in the two groups in the long-term. It is a viable treatment option in cases of lower extremity trauma. Amputation must not be considered as a failure, but a deliberate choice due to the functional impact of complications that occur after limb-salvage.

LEVEL OF EVIDENCE

Level IV study.

The concept of a waiting period for preoperative patient consent: Prospective study of 51 shoulder arthroscopy cases

INTRODUCTION

The French Code of Public Health (CSP) does not explicitly require that patients should be given a certain amount of time to think about a procedure, except for cosmetic surgery, where 15 days is required (Art. L 6322-2 CSP). We hypothesized that patients require a waiting period during their decision-making process for scheduled shoulder arthroscopy procedure.

MATERIALS AND METHODS

This prospective observational study of 51 patients analysed the concept of a waiting period based on a 10-item questionnaire. A comparative statistical approach was used and the P values were calculated using a paired Wilcoxon rank-sum test.

RESULTS

Of the 51 patients, 42 (82%) rejected the concept of a waiting period before the procedure and 37 patients (73%) did not want a mandatory waiting period imposed by law.

DISCUSSION

This study looked at the decision-making process during scheduled orthopaedic surgery and differentiated between the conscious and unconscious approach corresponding to an active and passive waiting period. A waiting period does not allow patients to make a conceptually deliberative decision that conforms to the criteria defined by the French Health Authority. This study rejects the need for a mandatory waiting period imposed on surgeons and patients as it does not integrate itself into the informative model of ethical decision-making for scheduled shoulder arthroscopy.

TYPE OF STUDY

Prospective, observational; level of evidence IV.

Defining Flare in Osteoarthritis of the Hip and Knee: A Systematic Literature Review — OMERACT Virtual Special Interest Group

Objective.

Beyond the exacerbation of pain in describing a flare in osteoarthritis (OA), patients and health professionals add other elements that deserve to be fully elucidated, such as effusion, swelling, and mobility limitation. To define and conceptualize the construct flare in OA, the objective was to identify the key variables, or symptoms, that worsen, and to clarify how these variables are described in the literature by patients and clinicians.

Methods.

A systematic review of the literature was conducted in Medline and PsychINFO. In brief, the search terms used were “osteoarthritis,” “knee,” “hip,” and “flare.” Specific characteristics of included studies were identified, including the type of study design, type of flare assessed, how the flare developed, and what definition of flare was used, including whether the definition was based on qualitative or quantitative analysis.

Results.

Pain was the major factor in the definition of flare within these studies. Four components of flare were identified: pain, other factors, composite criteria, and global assessment. While the majority of studies reported flare as an increase in pain using standardized outcome measures, only 1 study reported the antecedents and consequences of a pain flare using qualitative methods.

Conclusion.

The use of flare as an outcome or inclusion criterion in rheumatology trials is a common occurrence; however, this review highlights the wide variation in the definitions of OA flare currently in use and the emphasis on the measurement of pain. This variation in definition does not allow for direct comparison between trials and limits interpretation of evidence.

[Active management of the second twin for vaginal delivery: ruptured versus intact membranes. Apropos a series of 182 patients]

AIM

The vaginal management of the second twin (T2) differs throughout our country. In 2009, the French National College of Gynecologists and Obstetricians released practice guidelines, with low-level evidence, encouraging active management of the second twin, using maneuvers with intact membrane.

PATIENTS AND METHODS

In our level III labour ward, these maneuvers are systematically performed when the second twin is in a breech or transverse presentation and after ruptured membranes in most cases. We studied 182 twin pregnancies with active management of the T2 at more than 28 weeks of gestation, from 1st January 1996 to 31st December 2010, by comparing the membrane status during delivery of T2.

RESULTS

The results did not show any significant differences between the two groups of patients concerning the neonatal or maternal results. The technique is feasible, even by residents. Our results show that total breech extraction of the second twin with ruptured membranes is feasible, which allows for reappraisal of the national recommendations.

CONCLUSION

In our practice, it is possible to actively deliver the T2 with ruptured membranes without altering maternal and fetal prognosis and thus simplifying learning for young doctors.

[Breech delivery and scarred uterus: a special obstetrical situation?]

AIM

The management of breech delivery in patients with a history of caesarean section is a special situation requiring to anticipate the delivery route if the usual prerequisites for the acceptance of vaginal breech delivery are present. Does a history of caesarean section imply a systematic refusal of vaginal delivery in case of breech presentation or an alternative to an iterative caesarean still exists?

MATERIALS AND METHODS

An observational study was undertaken in our level III labour ward from January 1st 1994 to June 30th 2010 on 91 patients with a history of caesarean section and who had breech deliveries of singleton pregnancies at more than 35weeks of amenorrhea. Maternal, obstetrical and neonatal parameters were collected. Patients were divided into three groups: vaginal delivery, caesarean section after an accepted vaginal birth trial, elective caesarean section.

RESULTS

The rate of an accepted vaginal birth trial was 24.2% (22 cases) with a 36.4% (eight patients) success rate in this group. There were two (2.9%) unplanned vaginal births. Fourteen patients (15.4%) had caesarian sections after an accepted vaginal birth trial: ten before labour and four during labour for dynamic dystocia or non-reassuring fetal status. Most caesarean sections before labour in case of an accepted vaginal birth trial were justified by an intercurrent factor requiring induction of labour. Neonatal factors did not show any increased morbidity or mortality in the vaginal birth group. No Apgar score was found to be less than or equal to 7 at 5minutes. Umbilical arterial pH and lactate measured as from 2001 were similar between the groups. Indeed, the mean arterial pH after vaginal birth was 7.19 as compared to 7.22 in case of caesarean section after an accepted vaginal birth trial, and 7.26 after elective caesarean section. Likewise, the mean lactate measurement was at 4.71mmol/L after vaginal birth versus 4.54 and 3.07 in the other two groups. Only neonates born after elective caesarean sections were transferred to intensive care (four cases).

CONCLUSION

Vaginal breech delivery in case of a scarred uterus is possible, if each obstetrical situation is correctly studied to authorize a vaginal birth trial after a careful selection of patients and a strict management of labour. Vaginal birth does not seem to increase maternal and neonatal morbidity and mortality in this situation.

[Diagnosis of myocarditis: description and assessment of available methods]

Myocarditis is a common disease in all age groups. Correct diagnosis of myocarditis is difficult, but of clinical and scientific importance. It is the aim of this review to describe and evaluate diagnostic possibilities. It is not possible to make a definitive diagnosis of myocarditis by electrocardiography, laboratory tests or echocardiography. Nor can techniques of nuclear medicine or coronary angiography provide an unequivocal diagnosis of myocarditis. Myocarditis can be diagnosed with certainty only by endomyocardial biopsy, which must be examined by histological, immunohistological and molecular techniques to obtain maximal sensitivity. But optimal diagnosis of a biopsy is subject to the problem of sampling error. Furthermore, myocardial biopsy is in practice used only rarely, despite a low complication rate. Thus the diagnosis of myocarditis is often based merely on suspicion. The limitations of standard methods employed so far have made cardiac magnetic resonance imaging (CMR) a valuable new additional test when there is the clinical suspicion of myocarditis. A myocardial biopsy will often reveal myocarditis in patients with cardiac symptoms and CMRI findings typical of myocarditis, especially if the biopsy was obtained near the area of contrast enhancement in the CMRI. CMRI can also be used for noninvasive and low-risk follow-up of functional parameters and tissue damage.

Structure of the mouse gene encoding parathyroid hormone-related peptide

The parathyroid hormone-related peptide (PTHRP) was initially isolated from tumors associated with the syndrome of humoral hypercalcemia of malignancy. The human PTHRP gene is a complex transcriptional unit which uses multiple promoters and contains alternatively spliced 3' exons that result in mRNAs encoding three different deduced products. We report here the structure of the mouse PTHRP gene. The mouse gene has a considerably simpler organization than its human counterpart. This organization includes a single 3' exon and an apparent single 3' splicing pathway, leading to an mRNA encoding a 139-amino acid mature PTHRP. In addition, the mouse gene appears to be predominantly under the control of a short proximal promoter element. By RNase protection analysis, we identified PTHRP mRNA in specimens prepared from a variety of normal rodent tissues, including a number of tissues not previously recognized as sites of PTHRP gene expression.

Identification of an up-stream promoter of the human parathyroid hormone-related peptide gene

Previous evidence has suggested that the human PTH-related peptide (PTHRP) gene uses two promoters, one a short down-stream element lying immediately between two 5' exons (1 and 2) and a second lying in an unknown up-stream location. We approached identification of the up-stream element in three steps. First, Northern analysis carried out using progressively 5' fragments of the gene as probes identified a candidate region some 2.5 kilobases up-stream of exon 1. Second, a battery of overlapping 5' cRNA probes was used in RNase protection experiments to identify two previously unrecognized exons, 212 and 93 basepairs in length (termed exons 1A and 1B to distinguish them from the previously designated exon 1, which was termed exon 1C). Third, primer extension experiments were performed with oligonucleotides complementary to each of the 5' exonic sequences. These experiments identified a transcription start site up-stream of exon 1A and also demonstrated that the 5' exons of the PTHRP gene could be spliced together in several combinations. The up-stream promoter element contains a TATA box, but does not otherwise resemble the down-stream PTHRP gene promoter or the PTH gene promoter. We conclude that the human PTHRP gene contains eight exons spanning more than 15 kilobases of genomic DNA, with promoter elements lying immediately up-stream of exons 1A and 2. The identification of these elements will permit functional analysis of their roles in mediating tissue- and tumor-specific PTHRP gene expression.

Regulation of parathyroid hormone-related peptide gene expression by cycloheximide

A novel parathyroid hormone-related peptide (PTHRP) has been isolated from tumors associated with the syndrome of humoral hypercalcemia of malignancy. The human PTHRP gene appears to use multiple promoters and contains alternatively spliced 3' exons which give rise to three PTHRP mRNA classes, each bearing multiple copies of an AU motif that has been associated with mRNA instability. We report here that inhibition of protein synthesis leads to the super-induction of PTHRP mRNA expression in a number of human and rat cell lines. This phenomenon was found to reflect both an increase in the rate of PTHRP gene transcription and a stabilization of PTHRP mRNAs. The transcriptional mechanism appears to preferentially involve the activity of a short downstream promoter of the gene, which is presumed to be regulated by a labile repressor protein. Our findings indicate that both transcriptional and posttranscriptional mechanisms may be important control points in the regulation of PTHRP expression in normal and malignant cells.

Glucocorticoid regulation of parathyroid hormone-related peptide gene transcription in a human neuroendocrine cell line

A PTH-related peptide (PTHRP) has been identified and its cDNA cloned from tumors associated with the syndrome of humoral hypercalcemia of malignancy. The PTHRP and PTH genes appear to represent members of a gene family. Whereas the PTH gene is expressed exclusively in the parathyroids, the PTHRP gene appears to be widely expressed, but little is known concerning the regulation of its expression in any site. We studied the regulation of PTHRP gene expression in a human carcinoid cell line (NCI-H727) which has neuroendocrine features and also produces calcitonin, calcitonin gene-related peptide, and chromogranin-A. We found that the synthetic glucocorticoid triamcinolone produced time- and dose-dependent decreases in steady state PTHRP and calcitonin mRNA levels in NCI-H727 cells. This effect was blocked by the competitive glucocorticoid inhibitor RU-486. Messenger RNA stability and transcription run-off experiments revealed that triamcinolone decreased PTHRP and calcitonin expression by repressing the transcription rates of both genes.

Expression of transcripts encoding a parathyroid hormone-related peptide in abnormal human parathyroid tissues

A PTH-related peptide (PTHRP) has been identified and its cDNA cloned from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The human PTHRP gene has been recently isolated and found to be a complex transcriptional unit using multiple promoters and containing alternatively spliced 3' exons which result in three mRNA classes, each class encoding a PTHRP with a unique carboxy-terminus. The PTHRP gene appears to be expressed in a number of normal tissues, and PTHRP transcripts have been previously reported to be overexpressed in a small sample of human parathyroid adenomas. In the present study we surveyed RNA prepared from a total of 60 abnormal human parathyroid glands for PTHRP gene expression using a combination of Northern blotting and RNase protection techniques. Apparent overexpression of PTHRP mRNA was observed in two thirds of parathyroid adenomas, whereas no overexpression was found in 7 examples of sporadic primary hyperplasia, 5 examples of secondary hyperplasia, and 3 examples of parathyroid carcinoma. Apparent overexpression was also observed in 1 of 4 cases of multiple endocrine neoplasia type 1, 1 of 2 examples of multiple endocrine neoplasia type 2, and 1 gland considered to represent tertiary hyperparathyroidism. Northern analysis of poly(A)+ RNA prepared from three representative adenomas using region-specific probes indicated that two putative promoters are used and revealed a pattern of preferential splicing of transcripts to include the most distal 3' exon. These findings suggest that the PTHRP gene is commonly overexpressed in adenomatous parathyroid glands, but not in sporadic primary hyperplasia, that this overexpression does not seem to be dependent on the use of a single specific promoter, and that adenomatous parathyroid cells appear to preferentially use one of several alternative splicing pathways. It is presently not known whether PTHRP is secreted by abnormal parathyroid tissues and, if so, in what form.

Transcriptional regulation of the parathyroid hormone-related peptide gene by glucocorticoids and vitamin D in a human C-cell line

A parathyroid hormone-related peptide (PTHRP) has been identified in human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The PTHRP and parathyroid hormone (PTH) genes appear to have arisen by duplication and to represent members of a gene family. PTHRP mRNAs have been demonstrated in a number of normal tissues, but little is known concerning the regulation of PTHRP gene expression in any site. We studied PTHRP gene expression in TT cells, a human C-cell line which also produces calcitonin and calcitonin gene-related peptide. We found that both the synthetic glucocorticoid, dexamethasone, and the active vitamin D metabolite, 1,25-dihydroxyvitamin D3, decreased steady-state PTHRP mRNA levels in TT cells in a time- and dose-dependent fashion. The dexamethasone effect was completely blocked by the glucocorticoid antagonist RU-486. 24,25-dihydroxyvitamin D3 was found to be inactive. Neither dexamethasone nor 1,25-dihydroxyvitamin D3 appeared to influence PTHRP mRNA stability in TT cells, and both agents were shown by nuclear transcription run-off assay to decrease PTHRP gene transcription. These findings indicate that the PTHRP gene is under the transcriptional control of glucocorticoids and vitamin D in a cell line with prototypical neuroendocrine features.

Clonal rat parathyroid cell line expresses a parathyroid hormone-related peptide but not parathyroid hormone itself

A novel parathyroid hormone-related peptide has been identified in tumors associated with the syndrome of humoral hypercalcemia of malignancy. Subsequently, mRNAs encoding this peptide have been found to be expressed in a number of normal tissues, including the parathyroids. Using Northern blotting, RNase protection, and immunochemical techniques, we examined a clonal rat parathyroid cell line originally developed as a model system for studying parathyroid cell physiology. We found that this line expresses the parathyroid hormone-related peptide but not parathyroid hormone itself. Secretion of the parathyroid hormone-related peptide varied inversely with extracellular calcium concentration, but neither calcium nor 1,25-dihydroxyvitamin D3 appeared to influence steady-state parathyroid hormone-related peptide mRNA levels. This clonal line may prove to be an interesting system for studying the factors responsible for tissue-specific parathyroid hormone and parathyroid hormone-related peptide gene expression.

Isolation and characterization of the human parathyroid hormone-like peptide gene

A parathyroid hormone-like peptide (PTH-LP) has recently been identified in human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The peptide appears to be encoded by a single-copy gene that gives rise to multiple mRNAs that are heterogeneous at both their 5' and their 3' ends. Alternative RNA splicing is responsible for the 3' heterogeneity and results in mRNAs encoding three different peptides, each with a unique C terminus. We have isolated and characterized the human PTHLP gene. The gene is a complex transcriptional unit spanning more than 12 kilobases of DNA and containing six exons. Two 5' exons encode distinct 5' untranslated regions and are separated by a putative promoter element, indicating that the gene either has two promoter or is alternatively spliced from a single promoter upstream of the first exon. The middle portion of the PTHLP gene, comprising exons 2-4, has an organizational pattern of introns and exons identical to that of the parathyroid hormone gene, consistent with a common ancestral origin of these two genes. Exon 4 of the PTHLP gene encodes the region common to all three peptides and the C terminus of the shortest peptide, and exons 5 and 6 encode the unique C termini of the other two peptides. Northern analysis of mRNAs from four human tumors of different histological types reveals the preferential use of 3' splicing patterns by individual tumors.

Expression of messenger ribonucleic acids encoding a parathyroid hormone-like peptide in normal human and animal tissues with abnormal expression in human parathyroid adenomas

A novel PTH-like peptide has recently been purified and cloned from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. We surveyed the expression of mRNAs encoding this peptide in normal tissues by Northern analysis. One or more low abundance hybridizing transcripts was identified in poly(A)+ RNA prepared from human keratinocytes, thyroid, bone marrow, and fibroblasts, from bovine hypothalamus, pituitary, parathyroid, adrenal cortex, and adrenal medulla, and from rat brain, stomach mucosa, and fetal but not adult liver. One or more hybridizing transcripts was also identified in poly(A)+ RNA prepared from a number of established lines, including rat pituitary (GH4), rat pheochromocytoma (PC 12), human osteosarcoma (TE-85), and human medullary carcinoma (TT) cells. Northern analysis of mRNAs from abnormal human parathyroid tissue revealed an overexpression of transcripts for the PTH-like peptide which appeared to be specific for adenomatous or autonomous glands. These findings suggest that the PTH-like peptide is expressed in a number of endocrine and nonendocrine tissues, that it is developmentally expressed in at least one tissue (fetal liver), and that the regulation of its expression is abnormal in human parathyroid adenomas.

Two distinct tumor-derived, parathyroid hormone-like peptides result from alternative ribonucleic acid splicing

A novel PTH-like peptide has recently been isolated and cloned from human tumors associated with the syndrome of humoral hypercalcemia of malignancy. The deduced product of the initial clones to be reported is a 177 amino-acid protein, consisting of a 36 amino-acid precursor sequence followed by a 141 amino-acid mature peptide. Southern analysis of genomic DNA is compatible with a single-copy gene, but Northern analysis of mRNAs from both tumors and normal tissues consistently reveals multiple hybridizing transcripts, suggesting the possibility of alternative RNA splicing. We provide here direct evidence of alternative RNA splicing by the identification of a second cDNA clone in a human renal carcinoma cDNA library. As compared to the initial clone, this cDNA contains a foreshortened 5'-untranslated region but is otherwise identical until the distal portion of the coding region, at which point it diverges completely to encode a 166 amino-acid mature peptide with 27 amino acids of unique C-terminal sequence. The relative lengths of the primary translation products encoded by these two cDNAs were confirmed by transcription and translation in vitro, and both products were shown to be processed by added microsomes. The unique 3'-ends of these two cDNAs, as well as that of a third cDNA isolated by another laboratory, were used to identify one or more hybridizing transcripts corresponding to each cDNA in mRNA from a human renal carcinoma as well as in mRNA from normal human keratinocytes. We conclude that alternative RNA splicing results in mRNAs which encode multiple PTH-like peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of transcripts encoding a parathyroid hormone-like peptide in messenger RNAs from a variety of human and animal tumors associated with humoral hypercalcemia of malignancy

The syndrome of humoral hypercalcemia of malignancy (HHM) appears to be mediated in many instances by a parathyroid hormone-like peptide, which has recently been purified, sequenced, and cloned. Using a probe representing the coding region of the human PTH-like peptide, we examined by Northern analysis poly (A)+ RNA from a variety of human and animal tumors associated with HHM. Hybridizing transcripts were identified in mRNA from each of 12 human and each of four animal HHM-associated tumors, with a complex hybridization pattern observed in the human mRNAs and a relatively simple pattern observed in the animal mRNAs. Poly (A)+ RNA prepared from tumors of similar histological types unassociated with HHM failed to hybridize with the probe. Messenger RNA-dependent biological activity from the animal tumors was entirely eliminated in a hybridization-arrest experiment using a complementary oligonucleotide spanning the region of homology between human PTH and the PTH-like peptide. These findings indicate that the PTH-like peptide is associated with the syndrome of HHM in a wide spectrum of tumor types from a variety of mammalian species and that the PTH-like sequence in the proximal amino terminus of the peptide is highly conserved.

Synthetic human parathyroid hormone-like protein stimulates bone resorption and causes hypercalcemia in rats

Parathyroid hormone-like adenylate cyclase-stimulating proteins (hACSPs) have been implicated as one of the calcemic, bone-resorbing agents in patients with humoral hypercalcemia of malignancy. We report the synthesis of an amino-terminal hACSP fragment, Tyr36 hACSP (1-36) amide. The synthetic hACSP is a potent agonist of renal membrane adenylate cyclase (Km, 1.7 X 10(-10)) and of bone cell adenylate cyclase (Km 1 X 10(-9)M). It is a potent bone-resorbing agent in vitro, stimulating 45Ca release from fetal rat long bones at a concentration of 10(-9) M. When infused via osmotic minipumps into rats, it is also a potent calcemic factor in vivo, inducing a rise in serum calcium from (mean +/- SD) 10.6 +/- 0.6 to 19.7 +/- 3.2 mg/dl when infused at 1.4 micrograms/h and from 9.9 +/- 0.7 to 11.4 +/- 1.2 mg/dl when infused at 0.14 micrograms/h. These findings indicate that biologically active hACSP fragments can be synthesized. One such synthetic peptide possesses the in vitro and in vivo bioactivities demonstrated in native, tumor-derived hACSPs. It is also a potent calcemic, bone-resorbing agent.

Synthetic and partially-purified adenylate cyclase-stimulating proteins from tumors associated with humoral hypercalcemia of malignancy inhibit phosphate transport in a PTH-responsive renal cell line

Hypophosphatemia and hyperphosphaturia characteristically occur in patients with humoral hypercalcemia of malignancy (HHM). To determine if a tumor product causes these abnormalities in phosphate metabolism, rather than, for example, hypercalcemia, we investigated the effect of partially-purified adenylate cyclase-stimulating activity (ACSA) from human and animal HHM-associated tumors on sodium-dependent phosphate transport (Na PiT) in a PTH-responsive renal epithelial cell line. Thirty minute exposure to 7 X 10(-10) MbPTH (1-34) equivalents of ACSA from the human and animal tumors, reduced NaPiT by 20% and 14%, respectively. We also recently isolated an adenylate cyclase-stimulating protein (hACSP) from two human tumors associated with HHM and identified a cDNA clone for this protein which encodes a 141 amino-acid peptide. Based on the deduced amino-acid sequence, we synthesized tyr36 (1-36) hACSP. This synthetic peptide induced a 22% decrease in the initial rate of NaPiT by the epithelial monolayer. Its inhibitory activity was roughly equipotent to that of bPTH (1-34). We conclude that the ACSP derived from HHM-associated tumors decreases phosphate transport in renal epithelial cells. This peptide appears to play a key role in mediating the changes in phosphate metabolism in this syndrome.

Identification of a cDNA encoding a parathyroid hormone-like peptide from a human tumor associated with humoral hypercalcemia of malignancy

Humoral hypercalcemia of malignancy is a common paraneoplastic syndrome that appears to be mediated in many instances by a parathyroid hormone-like peptide. Poly(A)+ RNA from a human renal carcinoma associated with this syndrome was enriched by preparative electrophoresis and used to construct an enriched cDNA library in phage lambda gt10. The library was screened with a codon-preference oligonucleotide synthesized on the basis of a partial N-terminal amino acid sequence from a human tumor-derived peptide, and a 2.0-kilobase cDNA was identified. The cDNA encodes a 177 amino acid protein consisting of a 36 amino acid leader sequence and a 141 amino acid mature peptide. The first 13 amino acids of the deduced sequence of the mature peptide display strong homology to human PTH, with complete divergence thereafter. RNA blot-hybridization analysis revealed multiple transcripts in mRNA from tumors associated with the humoral syndrome and also in mRNA from normal human keratinocytes. Southern blot analysis of genomic DNA from humans and rodents revealed a simple pattern compatible with a single-copy gene. The gene has been mapped to chromosome 12.

Human U2 small nuclear RNA genes contain an upstream enhancer

The human U1 and U2 snRNA genes lack an obvious TATA box, but are extremely powerful RNA polymerase II transcription units capable of accurately initiating at least one transcript per gene every 2-4 s. We have investigated the location of cis-acting regulatory elements within the flanking sequences of human U2 and U1 genes. By introducing marked human U2 genes into HeLa cells on SV40- and pUC13-based vectors, we found that transient expression of the marked U2 gene did not require the SV40 enhancer. The U2 promoter element responsible for SV40 enhancer-independent U2 expression was localized within the 5'-flanking sequence of the gene, and shown to stimulate transcription from the U2 basal promoter in an orientation- and position-independent fashion. In addition, the U2 element could be functionally replaced by either the SV40 enhancer or by distal sequences from the human U1 promoter. We conclude that the human U2 and U1 genes contain functionally equivalent enhancer elements. Moreover, since the human U2 enhancer sequences resemble the Xenopus U2 enhancer-like element, enhancers appear to be a general feature of vertebrate snRNA promoter structure.

U1 small nuclear RNA genes are subject to dosage compensation in mouse cells

Multiple copies of a gene that encodes human U1 small nuclear RNA were introduced into mouse C127 cells with bovine papilloma virus as the vector. For some recombinant constructions, the human U1 gene copies were maintained extrachromosomally on the viral episome in an unrearranged fashion. The relative abundance of human and mouse U1 small nuclear RNA varied from one cell line to another, but in some lines human U1 RNA accounted for as much as one-third of the total U1. Regardless of the level of human U1 expression, the total amount of U1 RNA (both mouse and human) in each cell line was nearly the same relative to endogenous mouse 5S or U2 RNA. This result was obtained whether measurements were made of total cellular U1 or of only the U1 in small nuclear ribonucleoprotein particles that could be precipitated with antibody directed against the Sm antigen. The data suggest that the multigene families encoding mammalian U1 RNA are subject to some form of dosage compensation.

The orir to ori+ mutation in spontaneous yeast petites is accompanied by a drastic change in mitochondrial genome replication

The orir petite mutants of Saccharomyces cerevisiae show a very low level of suppressivity (5-12%; suppressivity is the percentage of diploid petites issued from a cross of the parental haploid petite with a wild-type cell), indicating a poor replication efficiency of their mitochondrial genome. The latter is made up of repeat units containing two inverted ori sequences and arranged as tandem pairs in inverted orientation relative to their nearest neighbors. After subcloning orir petites or crossing with wild-type cells a large number of ori+ petites are found in the progeny. In contrast to the orir petites, from which they are derived, these ori+ petites are characterized by high suppressivity levels (approx. 90%) and contain mitochondrial genomes made up of tandem repeat units containing single ori sequences. The structural changes underlying the orir to ori+ mutation are therefore accompanied by a dramatic increase in suppressivity, indicating that the elimination of inverted ori sequences causes a drastic change from very poor to very good replicative efficiency in the mitochondrial genome. Finally, crosses of ori0 petites with wild-type cells were also studied; the results obtained have clarified the reasons for the high frequency of petites having genomes similar to those of orir petites after mutagenesis with ethidium bromide.

The mitochondrial genomes of spontaneous orir petite mutants of yeast have rearranged repeat units organized as inverted tandem dimers

We have investigated the structure and organization of the mitochondrial genomes of two related orir (ori-rearranged) spontaneous petite mutants of Saccharomyces cerevisiae. In these mutant genomes every repeat unit contains an inverted terminal duplication harboring a second (inverted) ori sequence, and tandem pairs of repeat units alternate with tandem pairs in inverted orientation. We have shown that orir genomes are organized as the genomes with inverted repeat units of ethidium bromide (EtBr)-induced petites, and we have clarified the mechanism by which such mutant mitochondrial genomes arise.

[Rupture of the left subclavian artery associated with fracture of the 1st rib]

Treatment in a case of partial rupture of the subclavicular artery, provoking subacute ischemia of the upper limb and associated with a fracture of the first rib, was by sternoclavicular disinsertion and resection-suture. The importance of systematic investigation of possible subclavicular lesions in patients with fractured first ribs is emphasized, both during the initial and follow-up examinations. The presence of a fracture of this type has little influence on the classical surgical attitude adapted, apart from the possible need for resection of the first rib.

Surrogate origins of replication in the mitochondrial genomes of ori-zero petite mutants of yeast

We have investigated the mitochondrial genome of eight ori-zero spontaneous petite mutants of Saccharomyces cerevisiae. The tandem repeat units of these genomes do not contain any of the seven canonical ori sequences of the wild-type genome. Instead, they contain one, or more, ori-S sequences. These 44-nucleotide long surrogate origins of replication are a subset of GC clusters characterized by a potential secondary fold with two sequences ATAG and GGAG , inserted in AT spacers, two AT base pairs just following them, a GC stem (broken in the middle, and, in most cases also near the base, by non-paired nucleotides), and a terminal loop. This structure is reminiscent of that of GC clusters A and B from canonical ori sequences and supports the view (Bernardi, 1982a ) that the GC clusters of the mitochondrial genome arose, by an expansion process, from the canonical ori sequences. Like the latter, ori-S sequences are present in both orientations, are located in intergenic regions, and can be used as excision sequences when tandemly oriented. Again as in the case of canonical ori sequences, the density of ori-S sequences on the repeat units of petite genomes are correlated with the replication efficiency of the latter, as assessed by the outcome of crosses with wild-type or petite tester strains.