The α-crystallin Chaperones Undergo a Quasi-ordered Co-aggregation Process in Response to Saturating Client Interaction

Small heat shock proteins (sHSPs) are ATP-independent chaperones vital to cellular proteostasis, preventing protein aggregation events linked to various human diseases including cataract. The α-crystallins, αA-crystallin (αAc) and αB-crystallin (αBc), represent archetypal sHSPs that exhibit complex polydispersed oligomeric assemblies and rapid subunit exchange dynamics. Yet, our understanding of how this plasticity contributes to chaperone function remains poorly understood. Using biochemical and biophysical analyses combined with single-particle electron microscopy (EM), we examined structural changes in αAc, αBc and native heteromeric lens α-crystallins (αLc) in their apo-states and at varying degree of chaperone saturation leading to co-aggregation, using lysozyme and insulin as model clients. Quantitative single-particle analysis unveiled a continuous spectrum of oligomeric states formed during the co-aggregation process, marked by significant client-triggered expansion and quasi-ordered elongation of the sHSP oligomeric scaffold, whereby the native cage-like sHSP assembly displays a directional growth to accommodate saturating conditions of client sequestration. These structural modifications culminated in an apparent amorphous collapse of chaperone-client complexes, resulting in the creation of co-aggregates capable of scattering visible light. Intriguingly, these co-aggregates maintain internal morphological features of highly elongated sHSP oligomers with striking resemblance to polymeric α-crystallin species isolated from aged lens tissue. This mechanism appears consistent across αAc, αBc and αLc, albeit with varying degrees of susceptibility to client-induced co-aggregation. Importantly, our findings suggest that client-induced co-aggregation follows a distinctive mechanistic and quasi-ordered trajectory, distinct from a purely amorphous process. These insights reshape our understanding of the physiological and pathophysiological co-aggregation processes of α-crystallins, carrying potential implications for a pathway toward cataract formation.

The α-crystallin chaperones undergo a quasi-ordered co-aggregation process in response to saturating client interaction

Small heat shock proteins (sHSPs) are ATP-independent chaperones vital to cellular proteostasis, preventing protein aggregation events linked to various human diseases including cataract. The α-crystallins, αA-crystallin (αAc) and αB-crystallin (αBc), represent archetypal sHSPs that exhibit complex polydispersed oligomeric assemblies and rapid subunit exchange dynamics. Yet, our understanding of how this plasticity contributes to chaperone function remains poorly understood. This study investigates structural changes in αAc and αBc during client sequestration under varying degree of chaperone saturation. Using biochemical and biophysical analyses combined with single-particle electron microscopy (EM), we examined αAc and αBc in their apo-states and at various stages of client-induced co-aggregation, using lysozyme as a model client. Quantitative single-particle analysis unveiled a continuous spectrum of oligomeric states formed during the co-aggregation process, marked by significant client-triggered expansion and quasi-ordered elongation of the sHSP scaffold. These structural modifications culminated in an apparent amorphous collapse of chaperone-client complexes, resulting in the creation of co-aggregates capable of scattering visible light. Intriguingly, these co-aggregates maintain internal morphological features of highly elongated sHSP scaffolding with striking resemblance to polymeric α-crystallin species isolated from aged lens tissue. This mechanism appears consistent across both αAc and αBc, albeit with varying degrees of susceptibility to client-induced co-aggregation. Importantly, our findings suggest that client-induced co-aggregation follows a distinctive mechanistic and quasi-ordered trajectory, distinct from a purely amorphous process. These insights reshape our understanding of the physiological and pathophysiological co-aggregation processes of sHSPs, carrying potential implications for a pathway toward cataract formation.

Conserved and divergent features of neuronal CaMKII holoenzyme structure, function, and high-order assembly

Neuronal CaMKII holoenzymes (α and β isoforms) enable molecular signal computation underlying learning and memory but also mediate excitotoxic neuronal death. Here, we provide a comparative analysis of these signaling devices, using single-particle electron microscopy (EM) in combination with biochemical and live-cell imaging studies. In the basal state, both isoforms assemble mainly as 12-mers (but also 14-mers and even 16-mers for the β isoform). CaMKIIα and β isoforms adopt an ensemble of extended activatable states (with average radius of 12.6 versus 16.8 nm, respectively), characterized by multiple transient intra- and inter-holoenzyme interactions associated with distinct functional properties. The extended state of CaMKIIβ allows direct resolution of intra-holoenzyme kinase domain dimers. These dimers could enable cooperative activation by calmodulin, which is observed for both isoforms. High-order CaMKII clustering mediated by inter-holoenzyme kinase domain dimerization is reduced for the β isoform for both basal and excitotoxicity-induced clusters, both in vitro and in neurons.

The CaMKII holoenzyme enables neuronal signal computation. In a comparative structure-function analysis of the neuronal α and β isoforms, Buonarati et al. find evidence for kinase domain dimers within the holoenzyme that enable a cooperative activation mechanism in both isoforms and inter-holoenzyme interactions that enable high-order aggregate formation under ischemic conditions.

Transpharyngeal echocardiographic imaging of the right and left carotid arteries

We present a technique for transpharyngeal imaging of the bilateral carotid arteries completed towards the end of a transesophageal echocardiogram. To our knowledge, this is the first report that demonstrates the bifurcation of the right common carotid artery into the right internal and external carotid arteries with a transesophageal echocardiographic probe.

Two- and three-dimensional transesophageal echocardiographic localization of a right atrial lipoma: importance of orienting echocardiographic images to the surgeon's view

We present a patient in whom the exact location of a right atrial lipoma identified with two- and three-dimensional transesophageal echocardiography (2-D and 3-D TEE) was correlated with the surgical findings. By orienting the 3-D TEE images to conform to the view of the surgeon from the right side of the patient and referencing the site of attachment of the tumor to the surrounding structures, this lipoma was correctly localized to a 7 o'clock position in the right atrium.

Recurrence of the acute HIV syndrome after interruption of antiretroviral therapy in a patient with chronic HIV infection: A case report

BACKGROUND

Clinical and virologic consequences of temporary interruption of HIV therapy are incompletely understood.

OBJECTIVE

To describe a febrile illness that was consistent with the acute HIV syndrome and occurred after interruption of antiretroviral therapy.

DESIGN

Case report.

SETTING

University clinic.

PATIENT

HIV-infected man.

MEASUREMENTS

Plasma viral load, lymphocyte subsets, diagnostic evaluation (including cultures and serologic tests), and analysis of lymph node tissue.

RESULTS

The patient began antiretroviral therapy 3 months after initial HIV exposure and had sustained viral suppression, except during a brief scheduled treatment interruption. One hundred sixty-nine days after resuming therapy, the patient discontinued it again immediately following an influenza vaccination. Eleven days later, he presented with a febrile mononucleosis-like syndrome associated with dramatic shifts in plasma HIV RNA level (<50 to >1 000 000 copies/mL) and CD4 cell count (0.743 x 10(9) cells/L to 0.086 x 10(9) cells/L). Evaluation for alternative causes of fever was unrevealing. Symptoms resolved rapidly with resumption of HIV therapy.

CONCLUSION

Therapeutic interruption may be associated with profound viral rebound and recurrence of the acute HIV syndrome.

Genomic organization of the UGT2b gene cluster on human chromosome 4q13

The UDP-glucuronosyltransferases (UGTs) comprise a large family of proteins capable of detoxifying a wide variety of both endogenous and exogenous substrates. The primary function of this gene superfamily is to catalyze the glycosylation of substrates such as biogenic amines, steroids, bile acids, phenolic compounds and various other pharmacologically relevant compounds, including numerous carcinogens, toxic environmental pollutants and prescription drugs. This conjugation increases the solubility of these compounds, allowing them to be excreted more readily through hepatic or renal mechanisms. This paper describes the genomic characterization and chromosomal localization of three UGT2B genes which together comprise part of a large cluster of related sequences, including pseudogenes found on human chromosome 4q13. A genomic map spanning approximately 500-1000 kb of this region reveals the presence of three previously described UGT2B genes, at least two previously uncharacterized pseudogenes and a significant number of remnant gene fragments and places UGT2B4 between UGT2B7 and UGT2B15. Additionally, access to a large reference DNA bank allowed us to calculate allele frequencies for two UGT2B SNPs: D85R in UGT2B15 and Q458D in UGT2B4 amongst 803 unrelated individuals representing five ethnic populations. The data presented here suggest a recent evolutionary history of gene duplication, mutation and rearrangement. Furthermore, they suggest that a re-evaluation of the current description of the UGT2B gene family with respect to the number of specific genes, degree of allelic diversity and molecular evolution may be necessary.

Simultaneous preservation of orchid seed and its fungal symbiont using encapsulation-dehydration is dependent on moisture content and storage temperature

Seeds of Dactylorhiza fuchsii (common spotted orchid) and Anacamptis morio (green-winged orchid) were encapsulated in alginate beads with hyphae of the basidomycete fungus Ceratobasidium cornigerum. Pre-treatment of beads for 18 h with sucrose at an optimum concentration of 0.75 M decreased the desiccation rate in a flow of sterile air (c. 23 degree C, 30% RH) and increased seed and fungal survival after up to 16 h drying. Pre-treated and 16-h dried beads were transferred to cryo-vials and subsequently stored at a range of low temperatures for up to 30 d. Neither embryo growth of both orchids nor fungal development was detrimentally affected by 1 d storage at -196 degree C when the beads were pre-dried to c. 20% moisture content. Encapsulated D. fuchsii seed and compatible fungus had < 5% and < 45% viability when beads of the same moisture content were stored for 1 d at -20 degree C and -70 degree C respectively. In contrast, viability of the seed and the fungus remained unchanged during 30 days storage at -196 degree C but was progressively lost at 16 degree C over the same interval. The results indicate opportunities for the use of simultaneous cryopreservation as a conservation tool for diverse taxa.

Transesophageal echocardiographic identification of left subclavian artery stenosis with steal phenomenon

In this report, we present the first case of the transesophageal echocardiographic identification of left subclavian artery stenosis and steal phenomenon.

Curriculum reform at the University of Otago Medical School

The University of Otago Medical School, the older of the two medical schools in New Zealand, identified during the 1980s many of the same problems with its undergraduate curriculum as were reported in the United States, Canada, and the United Kingdom. An early, overly ambitious attempt to introduce a full problem-based learning curriculum at Otago failed; however, many piecemeal changes that embodied some of the principles of problem-based learning were successfully implemented. Subsequently, as desire for more coordinated and substantive change grew, Otago's faculty used what they had learned from their first effort to successfully introduce a modular systems-based preclinical curriculum in 1997. The authors describe the features of the new curriculum and discuss two components (a systems-integration course and a large-scale program of computerized in-course testing) that are particularly innovative. The new curriculum is already achieving one of its main goals (increasing the perceived relevance of preclinical teaching) and other outcomes are being evaluated.

Clinical outcomes of the Otago-Southland Breast Cancer Screening Programme 1991-1996

AIM

To document the clinical outcome of the Otago-Southland Breast Cancer Screening Programme through its first two rounds of screening, from 1991-1996.

METHODS

Review and analysis of clinical and pathological records.

RESULTS

In the first round of screening, 13,876 women were screened, giving 75% uptake; 12.2% were referred for assessment and 126 cancers detected, 9.1 per thousand women screened. For the 9946 incidence screens in the second round, 3.9% of women screened were referred to assessment and 50 cancers detected, 5.0 per thousand women screened. The uptake and cancer detection rates exceed the targets and exceed other published results; the size distribution of the cancers detected was comparable to the Swedish two-counties study, showing that the results should produce an ultimate mortality reduction. The referral rate to assessment was higher than expected in the first round of screening, but within the targeted range in the second round. The benign to malignant ratio for all biopsies was 1.4:1 for the prevalence screen of the first round and 1.2:1 for the incidence screens in the second round, both exceeding the targets set.

CONCLUSIONS

The results show that the uptake and clinical results of the programme exceed expectations and that a large number of small invasive tumours have been successfully detected. These results are comparable to the best of overseas studies, and give confidence that mortality reductions will ultimately occur.

Chromosomal basis of X chromosome inactivation: identification of a multigene domain in Xp11.21-p11.22 that escapes X inactivation

A number of genes have been identified that escape mammalian X chromosome inactivation and are expressed from both active and inactive X chromosomes. The basis for escape from inactivation is unknown and, a priori, could be a result of local factors that act in a gene-specific manner or of chromosomal control elements that act regionally. Models invoking the latter predict that such genes should be clustered in specific domains on the X chromosome, rather than distributed at random along the length of the X. To distinguish between these possibilities, we have constructed a transcription map composed of at least 23 distinct expressed sequences in an approximately 5.5-megabase region on the human X chromosome spanning Xp11.21-p11.22. The inactivation status of these transcribed sequences has been determined in a somatic cell hybrid system and correlated with the position of the genes on the physical map. Although the majority of transcribed sequences in this region are subject to X inactivation, eight expressed sequences (representing at least six different genes) escape inactivation, and all are localized to within a region of less than 370 kb. Genes located both distal and proximal to this cluster are subject to inactivation, thereby defining a unique multigene domain on the proximal short arm that is transcriptionally active on the inactive X chromosome.

Pilot studies of in-course assessment for a revised medical curriculum: II. Computer-based, individual

PURPOSE

To test a computer-based method of in-course assessment for a modular, systems-oriented medical curriculum at the University of Otago Medical School.

METHOD

For the in-course assessment in anatomic pathology, 193 students completed five biweekly (i.e., every two weeks), criterion-referenced, computer-based quizzes incorporating many digitized photographs and a variety of question formats. The students signed up to take quizzes at any of ten available times during each quiz week. A score of 70% was required for passing each quiz, but the students could retake quizzes up to two more times in alternative versions. The students' opinions about biweekly testing and computer-based testing were sought.

RESULTS

All 193 students satisfactorily completed the assessment program, with no significant problems with hardware, software, or administration during the more than 1,000 computer-based quizzes. The students valued the bi-weekly quizzes as a stimulus for study and for feedback. They strongly supported computer-based quizzes, identifying a variety of benefits in their responses to the questionnaire. The staff found that development of visually rich quizzes was greatly facilitated by the use of computers.

CONCLUSION

The study confirmed the feasibility of using regular, computer-based quizzes for in-course assessment of a large medical school class and demonstrated assessments of a kind that would be difficult to achieve by means other than with computers.

Pilot studies of in-course assessment for a revised medical curriculum: I. Paper-based, whole class

PURPOSE

To test a paper-based method of in-course assessment for a modular, systems-oriented medical curriculum at the University of Otago Medical School.

METHOD

In 1996, 193 students took paper-based quizzes on the first four topics of a course in clinical biochemistry. A score of 75% was required for passing, but students could retake quizzes. The subsequent test on these four topics was constructed from questions used in previous years. The next four topics were taught without quizzes. The test on these topics was again constructed from questions used in past years. The authors examined the performances on the quizzes and tests and sought the students' opinions about the program.

RESULTS

72.0-95.3% of the students passed the quizzes the first time and 94.8-99.5% passed by the second version. Performance on the subsequent test items was higher than [corrected] when the items had been used previously; so was performance on three of the four questions for the next four topics, none of which had been accompanied by quizzes. Students valued the quizzes as a stimulus to study and as feedback. They preferred the segment of the course with the quizzes to the segment without them.

CONCLUSION

This method of in-course assessment was easy to administer and highly acceptable to the students. Performance on the quizzes was more than satisfactory and a passing score of 75% was reasonable. Such quizzes appeared to be able to replace a test that required explanation of answers while increasing the numbers of questions that could be asked and decreasing the marking time.

Autism and multiple exostoses associated with an X;8 translocation occurring within the GRPR gene and 3' to the SDC2 gene

An X;8 translocation was identified in a 27-year-old female patient manifesting multiple exostoses and autism accompanied by mental retardation and epilepsy. Through molecular analysis using yeast artificial chromosomes (YACs) and cosmid clones, the translocation breakpoint was isolated and confirmed to be reciprocal within a 5'-GGCA-3' sequence found on both X and 8 chromosomes without gain or loss of a single nucleotide. The translocation breakpoint on the X chromosome occurred in the first intron of the gastrin-releasing peptide receptor (GRPR) gene and that on chromosome 8 occurred approximately 30 kb distal to the 3' end of the Syndecan-2 gene (SDC2), also known as human heparan sulfate proteoglycan or fibroglycan. The GRPR gene was shown to escape X-inactivation. A dosage effect of the GRPR and a position effect of the SDC2 gene may, however, contribute the phenotype observed in this patient since the orientation of these genes with respect to the translocation was incompatible with the formation of a fusion gene. Investigation of mutations in these two genes in unrelated patients with either autism or multiple exostoses as well as linkage and association studies is needed to validate them as candidate genes.

Pituitary lineage determination by the Prophet of Pit-1 homeodomain factor defective in Ames dwarfism

The gene apparently responsible for a heritable form of murine pituitary-dependent dwarfism (Ames dwarf, df) has been positionally cloned, identifying a novel, tissue-specific, paired-like homeodomain transcription factor, termed Prophet of Pit-1 (Prop-1). The df phenotype results from an apparent failure of initial determination of the Pit-1 lineage required for production of growth hormone, prolactin or thyroid-stimulating hormone, resulting in dysmorphogenesis and failure to activate Pit-1 gene expression. These results imply that a cascade of tissue-specific regulators is responsible for the determination and differentiation of specific cell lineages in pituitary organogenesis.

X inactivation analysis and DNA methylation studies of the ubiquitin activating enzyme E1 and PCTAIRE-1 genes in human and mouse

Previously reported data on the X inactivation status of the ubiquitin activating enzyme E1 (UBE1) gene have been contradictory, and the issue has remained unsettled. Here we present three lines of evidence that UBE1 is expressed from the inactive X chromosome and therefore escapes X inactivation. First, by RNA in situ hybridization, UBE1 RNA is detected from both the active and inactive X chromosomes in human female fibroblasts. Second, UBE1 is expressed in a large panel of somatic cell hybrids retaining inactive human X chromosomes, including two independent hybrids that did not require UBE1 expression for survival. And third, sites at the 5' end of UBE1 are unmethylated on both active and inactive X chromosomes, consistent with the gene escaping inactivation. In order to address whether other genes that escape inactivation map to the same region of the X chromosome, we have also examined the expression of genes mapping adjacent to UBE1. The gene for PCTAIRE-1 (PCTK1) maps within 5 kb of UBE1 and similarly escapes X inactivation by the somatic cell hybrid assay, whereas six other genes that are within 1 Mb of UBE1 in Xp11.23 are silenced on the inactive X chromosome. Comparative mapping studies of the homologous loci in mouse establish that Ube1-x and Pctk1 are also within close physical proximity on the murine X chromosome, and expression studies of the Pctk1 gene determine that, similar to Ube1-x, it is subject to X inactivation in mouse. Methylation of CpG residues at restriction sites at the 5' end of both genes on the murine inactive X chromosome is consistent with both genes being subject to X inactivation in mouse, in contrast to their expression status in humans.

Molecular definition of breakpoints associated with human Xq isochromosomes: implications for mechanisms of formation

To test the centromere misdivision model of isochromosome formation, we have defined the breakpoints of cytogenetically monocentric and dicentric Xq isochromosomes (i(Xq)) from Turner syndrome probands, using FISH with cosmids and YACs derived from a contig spanning proximal Xp. Seven different pericentromeric breakpoints were identified, with 10 of 11 of the i(Xq)s containing varying amounts of material from Xp. Only one of the eight cytogenetically monocentric i(Xq)s demonstrated a single alpha-satellite (DXZ1) signal, consistent with classical models involving centromere misdivision. The remaining seven were inconsistent with such a model and had breakpoints that spanned proximal Xp11.21: one was between DXZ1 and the most proximal marker, ZXDA; one occurred between the duplicated genes, ZXDA and ZXDB; two were approximately 2 Mb from DXZ1; two were adjacent to ALAS2 located 3.5 Mb from DXZ1; and the largest had a breakpoint just distal to DXS1013E, indicating the inclusion of 8 Mb of Xp DNA between centromeres. The three cytologically dicentric i(Xq)s had breakpoints distal to DXS423E in Xp11.22 and therefore contained > or = 12 Mb of DNA between centromeres. These data demonstrate that the majority of breakpoints resulting in i(Xq) formation are in band Xp11.2 and not in the centromere itself. Therefore, we hypothesize that the predominant mechanism of i(Xq) formation involves sequences in the proximal short arm that are prone to breakage and reunion events between sister chromatids or homologous X chromosomes.

Surgical management of complete atrioventricular septal defects. A twenty-year experience

Creation of a competent left atrioventricular valve is a cornerstone in surgical repair of complete atrioventricular septal defects. To identify risk factors for mortality and failure of left atrioventricular valve repair and to determine the impact of cleft closure on postoperative atrioventricular valve function, we retrospectively analyzed hospital records of 203 patients between January 1974 and January 1995. Overall early mortality was 7.9%. Operative mortality decreased significantly over the period of the study from 19% (4/21) before 1980 to 3% (2/67) after 1990 (p = 0.03). Ten-year survival including operative mortality was 91.3% +/- 0.004% (95% confidence limit): all survivors are in New York Heart Association class I or II. Preoperative atrioventricular valve regurgitation was assessed in 203 patients by angiography or echocardiography and was trivial or mild in 103 (52%), moderate in 82 (41%), and severe in 18 (8%). Left atrioventricular valve cleft was closed in 93% (189/203) but left alone when valve leaflet tissue was inadequate and closure of the cleft might cause significant stenosis. Reoperation for severe postoperative left atrioventricular valve regurgitation was necessary in eight patients, five of whom initially did not have closure of the cleft and three of whom had cleft closure. Six patients had reoperation with annuloplasty and two patients required left atrioventricular valve replacement. Five patients survived reoperation and are currently in New York Heart Association class I or II. On most recent evaluation assessed by angiography or echocardiography (a mean of 59 months after repair), left atrioventricular valve regurgitation was trivial or mild in 137 of the 146 survivors (94%) examined; none had moderate or severe left atrioventricular valve stenosis. By multiple logistic regression analysis, strong risk factors for early death and need for reoperation included postoperative pulmonary hypertensive crisis, immediate postoperative severe left atrioventricular valve regurgitation, and double-orifice left atrioventricular valve. These results indicate that complete atrioventricular septal defects can be repaired with low mortality and good intermediate to long-term results. Routine approximation of the cleft is safe and has a low incidence of reoperation for left atrioventricular valve regurgitation.

Three genes that escape X chromosome inactivation are clustered within a 6 Mb YAC contig and STS map in Xp11.21-p11.22

In order to study the distribution of genes that escape X chromosome inactivation, a high density yeast artificial chromosome (YAC) contig and STS map spanning approximately 6 Mb has been constructed in Xp11.21-p11.22. The contig contains 113 YACs mapped with 53 markers, including 10 genes. Four genes have been assayed for their expression status on both the active and inactive human X chromosomes, and these data have been combined with previous results on two other genes in the contig. Three of these genes escape X inactivation and have been localized to a single YAC clone of approximately 1075 kb. The other three genes are subject to inactivation, with two of them lying among the genes that escape inactivation. These results suggest that there are both regional control signals as well as gene-specific elements that determine the X inactivation status of genes on the proximal short arm of the human X chromosome.

The DXS423E gene in Xp11.21 escapes X chromosome inactivation

The DXS423E gene has been localized to Xp11.21 and is expressed in somatic cell hybrids retaining either the human active or inactive X chromosome, demonstrating that DXS423E escapes X chromosome inactivation. The XE169 (DXS1272E or SMCX) gene that escapes X chromosome inactivation is also located in Xp11.21-11.22 and maps within the same YAC as DXS423E. Thus the DXS423E and XE169 genes define a new region in the proximal short arm of the X chromosome that is not subject to X chromosome inactivation, supporting a regional basis for escape from inactivation.

Breast reduction for symptomatic macromastia: can objective predictors for operative success be identified?

The purpose of this paper is to assess symptomatic macromastia, the relief of symptoms by operation, and predictors of symptom relief. The methods used have been retrospective chart review and a self-assessment patient questionnaire. One-hundred and thirty-three patients underwent an average 1660-gm reduction. Ninety-three percent reported a postoperative decrease in symptoms such as shoulder grooves and shoulder, neck, and back pain. Correlation between breast size and sign or symptom severity achieved significance only for the preoperative submammary rash (r = 0.33, p < 0.001). Patients lost an average of 8.9 lb postoperatively and were less overweight (49 versus 40 percent). Activity level increased postoperatively in 63 percent. Postoperative chest size correlated inversely with activity level (r = 0.35, p < 0.001). Thirty-nine percent of patients who took pain medications preoperatively were able to eliminate these postoperatively. The quantity of tissue removed did not correlate with outcome. A model predictive of symptom relief could not be developed (total R2 = 0.03). Reduction mammaplasty promoted relief of signs and symptoms of macromastia, but a predictive model of successful operation could not be developed.

Breast reconstruction: systemic factors influencing local complications

One hundred seven consecutive breast reconstructions in 83 women were retrospectively reviewed. The reconstructions were with subpectoral prostheses, 54 with permanent tissue expanders, 14 with temporary tissue expanders, and 39 with permanent implants. Immediate breast reconstruction was performed in 69 (64%) breasts and delayed breast reconstruction in 38 (36%) breasts. Risk factors for local complication were diabetes, smoking, age older than 60 years, obesity, and hypertension. Technical factors reviewed included timing of reconstruction, type of prosthesis used, and the presence or absence of drains. Women with immediate breast reconstruction sustained a significantly higher complication rate than women with delayed breast reconstruction; however, the majority of these were due to the antecedent mastectomy. Complications due to the reconstruction were not significantly different for women with immediate versus delayed breast reconstruction. Implant loss occurred in 5 women, 4 with immediate and 1 with delayed breast reconstruction (5.8% vs. 2.6%, p approximately 0.47). Diabetes was significant, and smoking and age greater than 60 years approached significance as risk factors for implant loss in women with immediate breast reconstruction (p approximately 0.01, 0.05, and 0.08, respectively). These risk factors also correlated directly with an increasing severity of complication in women with immediate breast reconstruction (r = 0.414, p = 0.06). Technical factors showed no significant effect on implant loss in women with immediate breast reconstruction.

Pericardial closure after cardiac operations. An animal study to assess currently available materials with particular reference to their suitability for use after coronary artery bypass grafting

An experimental study to assess the performance of currently available pericardial substitutes is described with particular reference to their use after coronary artery bypass grafting. Seventy-two ewes, (six groups of 12 animals) had a 7 x 5 cm portion of the pericardium excised. Each group had either the defect left open, primarily resutured, replaced with coarse Dexon No. 2 mesh (American Cyanamid Co., Danbury, Conn.), replaced with fine Dexon No. 8 mesh, replaced with glutaraldehyde-preserved bovine pericardium, or replaced with polytetrafluoroethylene 0.1 mm surgical membrane. Six animals from each group were assessed at 3 months and the remaining six animals were assessed at 6 months. The open-defect and resutured groups served as control animals. None of the substitutes proved superior to the open-defect group in the prevention of chest wall/lung-to-pericardium adhesions at either 3 or 6 months. The limitations of the animal model in assessing this aspect of substitute performance are discussed. Whereas the bovine pericardium, polytetrafluorethylene, and Dexon No. 8 mesh groups were superior to the resutured group in the prevention of pericardium-to-epithelium adhesions in the area of the patch, this advantage was lost at 6 months when resuturing proved as effective as polytetrafluoroethylene and bovine pericardium. In all groups there was little tendency to produce generalized pericardial adhesions. At 3 months Dexon No. 8 mesh and bovine pericardium produced the least amount of significant epicardial reaction. In two animals in the 3-month polytetrafluoroethylene group and in one animal in the 6-month polytetrafluoroethylene group, a "fibrous peel" was encountered on the inner surface of the patch, which had also become adherent to the epicardium and had obscured the underlying anatomy. At 6 months the open-defect, resutured, and bovine pericardium groups had produced no significant epicardial reaction. In one animal at 6 months the bovine pericardium had become markedly thickened and degenerative. We do not recommend routine closure of the pericardium after coronary artery operations with any of the substitutes investigated in our study.

The lack of effect of nifedipine on failing skin flaps

The calcium channel blocker, nifedipine, was administered to 16 pigs in randomized blinded fashion in an unsuccessful attempt to salvage failing random pattern flaps. Despite the moderate dose of drug used, nifedipine caused significant hypotension that may have countered any beneficial effect on small vessel flow. Further studies are needed before nifedipine is abandoned as a potential agent for the pharmacologic manipulation of failing skin flaps.

Reversal in the seasonal clustering of diabetes in multiplex families

We studied attributes of diabetic sib pairs in 138 insulin-dependent multiplex families. Within multiply affected families, there is a large subset of siblings diagnosed only a year or less apart in whom the usual seasonal variation for diabetes is reversed. Furthermore, we confirm that affected sibs tend to cluster for onset of disease. The clustering, however, is limited to those sibs younger than 20 yr. These diabetic patients cannot be categorized by HLA type, and a common environment may play a major role in the development of insulin-dependent diabetes.

COCTAILS: automated interlibrary loan statistics at health sciences library, SUNYAB

An automated interlibrary loan statistics compilation system used at the Health Sciences Library at the State University of New York at Buffalo is described. The system provides standardized input to produce various statistical reports as well as additional information for collection development and improved user service.