Loss of heterozygosity at the mannose 6-phosphate insulin-like growth factor 2 receptor gene correlates with poor differentiation in early breast carcinomas

Chromosome 6q has been shown to be one of the most frequent sites for allelic loss in human breast cancer. The mannose 6-phosphate/insulin-like growth factor 2 receptor (IGF2R) gene, which maps to chromosome 6q26-27, functions in the activation of TGF-beta1, a potent growth inhibitor for most cell types, the degradation of the mitogen IGF2 and the intracellular trafficking of lysosomal enzymes. Loss of heterozygosity (LOH) at the IGF2R locus with mutations in the remaining allele have been reported in liver cancers and recently in two high-grade cases of ductal carcinoma in situ of the breast. We have sought to confirm that allelic loss of IGF2R is an early event in the aetiology of breast cancer by screening a group of 'early' lesions for LOH at a polymorphic microsatellite marker within the IGF2R gene using polymerase chain reaction (PCR). Several microdissected tumour foci were analysed for each of 40 mammographically detected invasive carcinomas and 22 cases of pure ductal carcinoma in situ (DCIS). None of 25 (62.5%) informative early invasive carcinomas showed any evidence of LOH. This group comprised predominantly of well- to moderately differentiated cases (95%). However, 4 out of 18 informative DCIS cases (22%) showed clear evidence of LOH. Three of these were poorly differentiated (high-grade) lesions. These data suggest that loss of heterozygosity at the IGF2R gene is associated with poor differentiation at this early stage of breast cancer development and progression.

Loss of heterozygosity at chromosome 6q in preinvasive and early invasive breast carcinomas

We have used polymerase chain reaction (PCR) analysis to study the incidence of allelic imbalance at four polymorphic microsatellite markers on chromosome 6q25.1-27, three dinucleotide repeats and one trinucleotide repeat, for microdissected tumour foci from a group of 75 'early' breast carcinomas. The tumours comprised 16 preinvasive cases of ductal carcinoma in situ (DCIS) and 59 mammographically detected early invasive carcinomas. Loss of heterozygosity (LOH) was detected at all four loci and in all types and grade of disease. The frequency of LOH ranged from 23% to 50% depending on the marker studied. The highest frequency of LOH was observed at the D6S186 locus for the cases of DCIS and at the oestrogen receptor locus for the invasive carcinomas. These data suggest that the inactivation of tumour-suppressor genes within this region on chromosome 6q is important for the development of these early lesions.

Amplification of specific mRNA from a single human renal glomerulus, with an approach to the separation of epithelial cell mRNA

A method has been developed by which single human glomeruli may be plucked from fresh renal biopsies under direct vision, followed by separation of mRNA using oligo-dT-linked paramagnetic beads. The mRNA was amplified by reverse transcription and polymerase chain reaction (RT-PCR). Primers for a variety of human and rat proteins have been developed. The quantity of the amplified cDNA was measured by an enzyme-linked immuno-sorbent assay (ELISA), where biotinylated forward strands of DNA were captured, probed with a fluorescein-conjugated DNA oligomer, and then assayed with an enzyme-linked anti-fluorescein antibody. The cDNA-linked beads are reported to be stable and can be reused with different primer sets, thus forming a "bank' of samples from cases with defined glomerular disorders, which can be used to address new questions as they arise. Using rat glomeruli, a method has been devised which permits at least partial separation of epithelial cell mRNA from mesangial and endothelial cell mRNA.

Yeast chitin synthases 1 and 2 consist of a non-homologous and dispensable N-terminal region and of a homologous moiety essential for function

Predicted protein sequences of fungal chitin synthases can be divided into a non-homologous N-terminal region and a C-terminal region that shows significant homology among the various synthases. We have explored the function of these domains by constructing a series of nested deletions, extending from either end, in the CHS1 and CHS2 genes of Saccharomyces cerevisiae. In both cases, most or all of the sequences encoding the non-homologous N-terminal region (one-third of the protein for Chs1p and about one-fourth for Chs2p) could be excised, with little effect on the enzymatic activity in vitro of the corresponding synthase or on its function in vivo. However, further small deletions (20-25 amino acids) into the homologous region were deleterious to enzymatic activity and function, and often led to changes in the zymogenic character of the enzymes. Similarly, relatively small (about 75 amino acids) deletions from the C-terminus resulted in loss of enzymatic activity and function of both synthases. Thus, it appears that all the information necessary for membrane localization, enzymatic activity and function resides in the homologous regions of Chs1p and Chs2p, a situation that may also apply to other chitin synthases.

Laparoscopic trans-peritoneal adrenalectomy: a preliminary report of 14 adrenalectomies

OBJECTIVES

Laparoscopic adrenalectomy offers the potential benefits of a smaller operation with more rapid hospital discharge, compared to open surgery. Only a few small series have been reported so far. We describe our preliminary experience of 14 adrenalectomies using this new technique.

DESIGN

Review of all adrenalectomies (with the preoperative intention of laparoscopic removal) performed in an endocrine unit whose surgeon already had abdominal laparoscopic experience, particularly with cholecystectomy.

PATIENTS AND MEASUREMENTS

Twelve patients (3 with Conn's syndrome, 3 Cushing's syndrome, 1 Cushing's disease, 2 phaeochromocytomas and 3 adrenal incidentalomas) were operated between September 1993 and February 1996. Operating times, operative technique, time from surgery to discharge, outcome and all complications were recorded prospectively. Comparative data were obtained from 14 consecutive open adrenalectomies performed by the same surgeon between February 1989 and February 1995.

RESULTS

Fourteen glands were removed, two with a cholecystectomy, in 12 operations. Operating time (mean (range) 120 (60-225) min) was reduced with experience. Positioning the patient in the right lateral position facilitated left adrenalectomy. Time to discharge (mean (range)) was 5.3 (1-12) days. There were relatively minor complications in three patients, including two with Cushing's syndrome: a hernia at a port site, intra-peritoneal/wound haemorrhage and a pressure sore. Time to discharge for open adrenalectomy (mean (range)) was 6.5 (2-11) days and one case was complicated by wound infection.

CONCLUSIONS

Laparoscopic adrenalectomy is a practical technique for appropriately trained surgeons who regularly undertake adrenalectomy. The smaller incisions offer potential advantages, particularly for patients with poor tissue quality due to Cushing's syndrome, but tissue haemorrhage may still be a problem in these patients. Time to hospital discharge was similar to that for open surgery.

Microsatellite instability in early sporadic breast cancer

We have studied the incidence of microsatellite instability at three trinucleotide repeats and seven dinucleotide repeats from five chromosomal regions, in a group of 30 mammographically detected 'early' invasive breast cancers and correlated its occurrence with clinicopathological parameters. The myotonic dystrophy (DM-1) trinucleotide repeat was analysed in 48 additional cases. In 4 out of 78 (5%) paired tumour-normal DNA samples we found evidence of somatic microsatellite instability at DM-1: a novel allele of a different size was seen in the tumour DNA which was not present in the normal DNA sample. All four tumours that showed evidence of instability were from the core group of 30 cases (13%) and were well or moderately differentiated, oestrogen receptor-positive, infiltrating ductal carcinomas. Two of these tumours were unstable at nine of ten loci studied, both trinucleotide and dinucleotide repeats. DNA prepared from different normal tissues showed no evidence of instability, for all four instability cases. These data indicate that microsatellite instability is specific to the tumour DNA and is an early event in the genesis of some sporadic breast cancers.

Efficacy of the Steri-Shield filtered exhaust helmet in limiting bacterial counts in the operating room during total joint arthroplasty

Filtered exhaust helmets (space suits) have been reported as efficacious in decreasing wound infections following joint arthroplasty procedures; however, strict experimental control of the many variables related to the incidence of clinical infection has been lacking in these studies, making support of such conclusions difficult. Any potential benefit of filtered exhaust helmets in the control of infection rates can be logically assigned to the reduction of airborne bacterial counts within the operating room. A study was done using the Steri-Shield helmet (Bio-Medical Devices, Irvine, CA) to define its efficacy in limiting airborne bacterial contaminates during total joint arthroplasty. Forty-eight paired prosthetic hip and knee cases were evaluated using a block experimentation design. One case of each pair was done with all surgical and scrub personnel cloaked in Steri-Shield filtered exhaust helmets and the other with the same personnel in conventional paper hoods and masks. Air samples were obtained with an Anderson two-stage viable particle sampler (Anderson Samplers, Atlanta, GA) placed immediately adjacent to the wound. Quantitative microbial cultures were obtained. The filtered exhaust helmet evaluated in this study provided no increased protection against bacterial contamination in the area of the surgical field than conventional paper hoods and masks.

High tibial osteotomy: an operation based on a spurious mechanical concept. A theoretic treatise

The biomechanical basis for high tibial osteotomy (HTO) is erroneously conceived, in that to unload the medial side of the knee, an osteotomy would have to be performed of sufficient magnitude to shift the lateral side of the knee joint far enough medially to intersect the dynamic axis, not the mechanical axis. The resulting angular deformity would be functionally and cosmetically unacceptable in the eyes of most patients and surgeons. To corroborate these theoretic considerations, and to define the angular deformity necessary to unload the medial side of the knee joint during the midstance phase of gait, a cadaver osteotomy model was used with compartmental loading defined by direct observation, as well as by load-sensitive film. As predicted, medial compartment unloading did not occur until the lateral side of the joint crossed the dynamic axis. In both cadavers tested, the extremity alignment necessary to unload the medial side was approximately 25 degrees valgus. The efficacy of HTO should be re-examined, as its biomechanical basis is fundamentally flawed.

Twenty-one-month follow-up study of school-age children exposed to Hurricane Andrew

OBJECTIVE

To explore the 21-month course of posttraumatic stress symptomatology (PTSS) and psychological morbidity in 30 school-age children (7 to 13 years) after exposure to Hurricane Andrew.

METHOD

Pynoos' Posttraumatic Stress Disorder Reaction Index and Achenbach's Teacher's Report Form were administered at 8 and 21 months after Hurricane Andrew.

RESULTS

At 21 months 70% of the children endorsed moderate-severe PTSS. The reduction in PTSS was greater for boys than girls. Psychopathology as measured by the Teacher's Report Form increased over the 19-month period. Boys demonstrated significant increases in internalizing symptoms and in Withdrawn, Anxious/Depressed, Social Problems, and Attention Problems scales, and girls showed a significant increase in the Anxious/Depressed scale.

CONCLUSIONS

Twenty-one months after exposure to Hurricane Andrew, there were continuing high levels of PTSS and evidence of increasing emotional and behavioral problems. While girls sustained higher levels of PTSS, boys demonstrated higher indices of other psychopathology. The enduring effects of disaster associated with secondary stressors and "traumatic reminders" continue to be etiologically important for continuing psychological morbidity.

Psychological effects of Hurricane Andrew on an elementary school population

OBJECTIVE

To explore the prevalence and progression of posttraumatic symptomatology (PTS), using emotional and behavioral indices of psychopathology in school-age children in the pathway of Hurricane Andrew (HI-IMPACT) and in a comparison group north of Miami (LO-IMPACT).

METHOD

Pynoos' Posttraumatic Stress Disorder Reaction Index and Achenbach's Teacher's Report Form (TRF) were administered 8 weeks and 32 weeks after the hurricane. In addition, 21 measures of disruptive behavior cataloged by Dade County Public Schools were aggregated and compared by grading period between pre- and posthurricane school years.

RESULTS

There were no statistically significant differences between the two schools in PTS at 8 weeks after the hurricane, although the children in the HI-IMPACT school were more likely to have severe PTS. TRF findings at 8 weeks revealed that children in the HI-IMPACT school evidenced lower means on the eight TRF scales and on the broader Internalizing and Externalizing measures. Analysis of the disruptive behavior revealed a drop in the marking period immediately after the hurricane in the HI-IMPACT area, but an opposite effect was observed in the LO-IMPACT area.

CONCLUSIONS

After the hurricane there was an initial increase in PTS and a concomitant decrease in other measures of behavior and psychopathology. PTS remained relatively high throughout the school year, but there was a rebound and subsequent normalization of the measures of disruptive behavior.

Hybrid fixation modular tibial prosthesis. Early clinical and radiographic results and retrieval analysis

A prosthetic tibial component has been designed with features for fixation to bone using a combination of acrylic cement and ingrowth interfaces. This hybrid concept affords the component the immediate stability of cement fixation and the potential long-term stability of biologic fixation. The ingrowth interfaces (coupled with the central stem) are intended to shield the cement interface beneath the tibial tray from the tensile liftoff forces that result from eccentric loading, while avoiding the fretting and osteolysis associated with screw fixation. A disassembly capability allows the tray to be removed from the stemmed anchorage assembly, facilitating component extraction and limiting bone loss. A clinical and radiographic review of 50 consecutive primary total knee arthroplasties with a mean follow-up period of 35 months revealed stable interfaces with no progressive radiolucencies and minimal remodeling changes. The mean Knee Society knee score was 92.2. At final follow-up evaluation, 88.6% of patients noted no or mild (occasional) pain. Retrieval of three prosthetic knees with chronic sepsis showed extensive ingrowth into the porous interfaces and an osteointegrated bony sleave around the smooth central stem.

Multiple myeloma. A differential consideration for osteolysis surrounding total hip arthroplasties

A diagnosis of multiple myeloma was made in a 77-year-old man based on the presence of focal periprosthetic osteolytic lesions surrounding a noncemented femoral component. The radiographic appearance of these lesions was remarkably similar to that of focal osteolytic lesions seen around stable prosthetic femoral components resulting from the localized accumulation of particulate debris. Multiple myeloma should be included in the differential diagnosis of osteolytic lesions around prosthetic components.

Segregation analysis of NIDDM in Caucasian families

Non-insulin-dependent diabetes mellitus (NIDDM) has a substantial genetic component, but the mode of inheritance and the molecular basis are unknown. We have undertaken segregation analysis of NIDDM after studying 247 subjects in 59 Caucasian nuclear pedigrees ascertained without regard to family history of the disorder. The analyses were performed using POINTER and COMDS, which are computer programs which apply statistical models to the data. POINTER analysis was performed defining the phenotype as a presence or absence of hyperglycaemia. Among single locus hypothesis, the analyses rejected a recessive model and favoured a dominant model, but could not statistically show that this fitted better than a mixed model (a single locus against a polygenic background) or a polygenic model. COMDS analysis assumed a continuum of hyperglycaemia from normality to NIDDM, classified family members into a series of diathesis classes with increasing plasma glucose levels and compared the distribution with that found by screening the normal population. This analysis improved the likelihood of a dominant single locus model and suggested a gene frequency of 7.4%. It raised the possibility of a second locus, but cannot identify or exclude a polygenic model. In conclusion, two types of segregation analyses rejected a recessive model and favoured a dominant model of inheritance, although they could not statistically show that this fitted better than the polygenic model. The results raised the possibility of a common dominant gene with incomplete penetrance, but genetic analysis of NIDDM needs to take into account the likelihood of polygenic inheritance with genetic heterogeneity.

MHC class II expression by microglia in tetanus toxin-induced experimental epilepsy in the rat

Minute amounts of tetanus toxin injected into the hippocampus of rats results in an epileptiform syndrome. When the toxin injection is made unilaterally or bilaterally into the ventral hippocampus, about one-third of animals with seizures show bilateral neuronal loss in dorsal CA1 of the hippocampus after 1 week. In animals with seizures, microglia in hippocampus are found to be activated. The present work shows that during the acute phase, microglia in the substantia nigra become activated and express MHC class II antigens in the majority of animals with seizures. After the animals have recovered from the acute phase at 8 weeks, the MHC class II expression has largely disappeared from the substantia nigra but MHC class II-expressing microglia are found in the dorsal hippocampus of those rats with loss of cells from CA1. These results show that microglia are responsive to abnormal electrical activity in the central nervous system in the absence of degenerative changes. Further studies are required to determine how microglia may contribute to the neuropathology of epilepsy.

Comparison of primate and canine models for bone ingrowth experimentation, with reference to the effect of ovarian function on bone ingrowth potential

Bone growth into porous composite (mesh-bead) titanium plugs was compared in elderly (postmenopausal) female monkeys and female dogs as a means of validating the cross-species interpretations so often made between data from research on dogs and human applications. The effect of oophorectomy on bone ingrowth in the canine model was defined by the comparison of data on fractional ingrowth in animals that had had oophorectomy and in control animals that had had a sham operation. No significant difference in bone growth into the experimental plugs was identified between the two animal models, which lends credence to cross-species interpretation of existing data from dogs. The presence or absence of active ovaries did not affect the ingrowth fraction in the canine model; this suggests that existing data are not confounded by the lack of control of ovarian function. Estrogen depletion does not appear to influence bone ingrowth adversely.

Association of low birth weight with beta cell function in the adult first degree relatives of non-insulin dependent diabetic subjects

OBJECTIVE

To examine the relation between birth weight and beta cell function in the first degree relatives of non-insulin dependent diabetic subjects.

DESIGN

Cross sectional study of 101 adults of known birth weight from 47 families which had at least one member with non-insulin dependent diabetes.

SUBJECTS

101 white adults aged mean 43 (SD 7) years.

SETTING

Oxfordshire, England.

MAIN OUTCOME MEASURES

Glucose tolerance was measured by continuous infusion glucose tolerance test. beta cell function and insulin sensitivity were calculated from the fasting plasma glucose and insulin concentrations with homeostasis model assessment. beta cell function was standardised to allow for the confounding effects of age and obesity.

RESULTS

Twenty seven subjects had non-insulin dependent diabetes, 32 had impaired glucose tolerance, and 42 were normoglycaemic. Birth weight correlated with the beta cell function of the complete cohort (rs = 0.29, p = 0.005), the non-insulin dependent diabetic subjects (rs = 0.50, p = 0.023), and the non-diabetic subjects (rs = 0.29, p = 0.013). The non-insulin dependent diabetic (n = 27) and the non-diabetic (n = 74) subjects had similar mean (inter-quartile range) centile birth weight 50% (19%-91%), and 53% (30%-75%) respectively. Non-insulin dependent diabetic subjects had significantly lower beta function than the non-diabetic subjects: 69% (48%-83%) v 97% (86%-120%), p < 0.001.

CONCLUSIONS

The cause of the association between low birth weight and reduced beta cell function in adult life is uncertain. Impaired beta cell function in non-insulin dependent diabetic subjects was not accounted for by low birth weight, and genetic or environmental factors are likely to be necessary for development of diabetes.

Internal fixation of proximal femur fractures: a biomechanical comparison of the Gamma Locking Nail and the Omega Compression Hip Screw

The fracture fixation capability of the Gamma Locking Nail was compared with the Omega Compression Hip Screw using cadaver femurs with simulated intertrochanteric and subtrochanteric fractures. Loading of the femurs was done on an Instron machine. Fracture fragment motion was recorded at 100-lb loading increments using standard roentgenograms. Both forms of hardware exhibited sufficient structural integrity to carry loads up to 600 lbs. Fracture motion was generally greater with the Gamma Locking Nail, which appeared to suspend the proximal fragments above a pivot point defined by the distal locking screws. Compression of the fracture site under loading did not occur with the Gamma Locking Nail. The potential for iatrogenic fracture generation appeared greater with the Gamma Locking Nail. Additionally, no clear mechanical advantage was documented in the fracture patterns tested. A limited discretionary use of the Gamma Locking Nail is advised.

Linkage analysis of glucokinase gene with NIDDM in Caucasian pedigrees

NIDDM has a strong genetic component, as evidenced by the high level of concordance between identical twins. The nature of the genetic predisposition has remained largely unknown. Recently, the glucokinase gene locus on chromosome 7p has been shown to be linked to a subtype of NIDDM known as MODY in French and British pedigrees, and glucokinase mutations have been identified. To study the relationship between the glucokinase gene and NIDDM, we performed a linkage analysis in 12 Caucasian pedigrees ascertained through a proband with classical NIDDM. The LINKAGE program was used under four models, including autosomal dominant and recessive, with individuals with glucose intolerance counted as either affected or of unknown status. Linkage was significantly rejected with the dominant models (LOD scores -4.65, -4.25), and was unlikely with the recessive model when glucose intolerance was considered as affected (LOD score -1.38). These findings suggest that mutations in or near the glucokinase gene are unlikely to be the major cause of the inherited predisposition to NIDDM in Caucasian pedigrees, but do not exclude a role for this locus with a polygenic model, or a major role in some pedigrees.

The influence of age, sex, and initial fit on bony ingrowth stabilization with the AML femoral component in primary THA

A radiographic review of 178 consecutive primary total hip arthroplasties using the AML femoral component with a mean follow up of 40.1 months identified 92.3% to be stabilized by bony ingrowth and 7.7% by fibrous tissue. None were classified as loose. The quality of fit in the isthmus and calcar regions was identified as an important factor in achieving bony ingrowth stabilization. Bony ingrowth was achieved in all age groups with equal frequency. No relationship between sex and the type of stabilization was identified. A clinical correlation utilizing a subset of patients with identical prosthetic components identified equivalent clinical results across all age groups. Thirty-four percent of patients experienced some residual thigh pain. No statistically significant relationship between the presence of thigh pain and the type of femoral component stabilization (bony vs fibrous) could be identified. Ninety-eight percent of patients expressed unconditional satisfaction with their hip replacements.

Angled bearing inserts in total knee arthroplasty. A brief technical note

Malalignment of total knee prosthetic components may lead to premature wear, loosening of components, or patellar instability. Unfortunately, removal of securely cemented or ingrown components is difficult and may be extremely destructive to the available bone stock. Angled bearing inserts provide a means to compensate for malpositioned components and should be considered an alternative to component removal in certain cases.

Sclerosing stromal tumor of the ovary: an ultrastructural and immunohistochemical analysis with histogenetic considerations

Sclerosing stromal tumors are rare, benign ovarian neoplasms of unknown etiology and histogenesis. Three sclerosing stromal tumors were evaluated by immunohistochemistry and electron microscopy and were compared to two thecomas and nonneoplastic ovarian mesenchymal tissue. The sclerosing stromal tumors and thecomas were positive for muscle-specific actin; immunoreactivity was intense in the cellular areas of the sclerosing stromal tumors and focal in the thecomas. This antigen was expressed in nonneoplastic stroma predominantly in a perifollicular (theca externa) distribution. Two sclerosing stromal tumors and both thecomas were vimentin positive. Desmin was present in nonvascular cells in one of each tumor type. Expression of vimentin diffusely and of desmin focally was present in nonneoplastic cortical stroma and surrounding follicles. All specimens were nonreactive for cytokeratin. Electron microscopy supported differentiation toward smooth muscle in the sclerosing stromal tumors but not in the thecomas. Such differentiation included aggregates of cytoplasmic filaments with interspersed dense bodies, pinocytotic vesicles, and basal lamina. Delicate, long processes interconnected cells, often with primitive junctions, in the hypocellular foci. Cytoplasmic lipid, which was present in the thecomas, was not well developed in the sclerosing stromal tumors. It is proposed that a population of muscle-specific actin-positive elements exists in the theca externa--the perifollicular myoid stromal cell--and that sclerosing stromal tumors may originate from them. Sclerosing stromal tumors and thecomas share many antigenic determinants and morphologic features and thus are probably closely related entities.

Chitinase and chitin synthase 1: counterbalancing activities in cell separation of Saccharomyces cerevisiae

Previous results [E. Cabib, A. Sburlati, B. Bowers & S. J. Silverman (1989) Journal of Cell Biology 108, 1665-1672] strongly suggested that the lysis observed in daughter cells of Saccharomyces cerevisiae defective in chitin synthase 1 (Chs1) was caused by a chitinase that partially degrades the chitin septum in the process of cell separation. Consequently, it was proposed that in wild-type cells, Chs1 acts as a repair enzyme by replenishing chitin during cytokinesis. The chitinase requirement for lysis has been confirmed in two different ways: (a) demethylallosamidin, a more powerful chitinase inhibitor than the previously used allosamidin, is also a much better protector against lysis and (b) disruption of the chitinase gene in chs1 cells eliminates lysis. Reintroduction of a normal chitinase gene, by transformation of those cells with a suitable plasmid, restores lysis. The percentage of lysed cells in strains lacking Chs1 was not increased by elevating the chitinase level with high-copy-number plasmids carrying the hydrolase gene. Furthermore, the degree of lysis varied in different chs1 strains; lysis was abolished in chs1 mutants containing the scs1 suppressor. These results indicate that, in addition to chitinase, lysis requires other gene products that may become limiting.

Biomechanical comparison of cannulated small bone screws: a brief follow-up study

The compressive forces generated by the ASIF and Herbert small bone cannulated screws were measured in the laboratory with the use of simulated bones and a custom-designed load washer as a means of quantifying their fixation capabilities. Comparative data were also generated for the Herbert scaphoid bone screw and the ASIF 4 mm cancellous screw. The cannulated Herbert bone screw and the ASIF 4 mm cancellous screw were found to have nearly identical compression capabilities. Both generated compression forces approximately five times those of the Herbert scaphoid bone screw. The ASIF small cannulated screw demonstrated a compressive capacity 2 1/2 times that of the Herbert screw.

Computer-aided design of two-dimensional electric-type hyperthermia applicators using the finite-difference time-domain method

A hyperthermia applicator design tool consisting of a finite-difference time-domain (FDTD) technique in combination with a graphical display of electric fields and normalized linear temperature rise is described. This technique calculates, rather than assumes, antenna current distributions; it includes mutual interactions between the body and the applicator, and it calculates driving-point impedance and power delivered to the applicator. Results show that the fundamental limitation of 2-D electric-type applicators is overheating of the fat by normal components of the electric field, which exist because of near fields and capacitive coupling with the muscle. Two factors which contribute to the capacitance are the muscle conductivity and the small antenna size in air. Two examples of applicators designed to avoid fat overheating are described: a 27-MHz segmented dipole for heating large tumors to 7 cm depth, and a 100-MHz dipole for small tumors to 5 cm depth. The first uses a water bolus, and the second uses a water bolus with low-permittivity strips to reduce normal fields at the antenna ends. The results of this study describe fundamental limitations of electric field applicators, and illustrate the use of a powerful applicator design tool that allows rapid evaluation of a wide range of ideas for applicators which would require months and years to test experimentally.

CAL1, a gene required for activity of chitin synthase 3 in Saccharomyces cerevisiae

The CAL1 gene was cloned by complementation of the defect in Calcofluor-resistant calR1 mutants of Saccharomyces cerevisiae. Transformation of the mutants with a plasmid carrying the appropriate insert restored Calcofluor sensitivity, wild-type chitin levels and normal spore maturation. Southern blots using the DNA fragment as a probe showed hybridization to a single locus. Allelic tests indicated that the cloned gene corresponded to the calR1 locus. The DNA insert contains a single open-reading frame encoding a protein of 1,099 amino acids with a molecular mass of 124 kD. The predicted amino acid sequence shows several regions of homology with those of chitin synthases 1 and 2 from S. cerevisiae and chitin synthase 1 from Candida albicans. calR1 mutants have been found to be defective in chitin synthase 3, a trypsin-independent synthase. Transformation of the mutants with a plasmid carrying CAL1 restored chitin synthase 3 activity; however, overexpression of the enzyme was not achieved even with a high copy number plasmid. Since Calcofluor-resistance mutations different from calR1 also result in reduced levels of chitin synthase 3, it is postulated that the products of some of these CAL genes may be limiting for expression of the enzymatic activity. Disruption of the CAL1 gene was not lethal, indicating that chitin synthase 3 is not an essential enzyme for S. cerevisiae.

The function of chitin synthases 2 and 3 in the Saccharomyces cerevisiae cell cycle

The morphology of three Saccharomyces cerevisiae strains, all lacking chitin synthase 1 (Chs1) and two of them deficient in either Chs3 (calR1 mutation) or Chs2 was observed by light and electron microscopy. Cells deficient in Chs2 showed clumpy growth and aberrant shape and size. Their septa were very thick; the primary septum was absent. Staining with WGA-gold complexes revealed a diffuse distribution of chitin in the septum, whereas chitin was normally located at the neck between mother cell and bud and in the wall of mother cells. Strains deficient in Chs3 exhibited minor abnormalities in budding pattern and shape. Their septa were thin and trilaminar. Staining for chitin revealed a thin line of the polysaccharide along the primary septum; no chitin was present elsewhere in the wall. Therefore, Chs2 is specific for primary septum formation, whereas Chs3 is responsible for chitin in the ring at bud emergence and in the cell wall. Chs3 is also required for chitin synthesized in the presence of alpha-pheromone or deposited in the cell wall of cdc mutants at nonpermissive temperature, and for chitosan in spore walls. Genetic evidence indicated that a mutant lacking all three chitin synthases was inviable; this was confirmed by constructing a triple mutant rescued by a plasmid carrying a CHS2 gene under control of a GAL1 promoter. Transfer of the mutant from galactose to glucose resulted in cell division arrest followed by cell death. We conclude that some chitin synthesis is essential for viability of yeast cells.

Experience with a modified posterior approach to the hip joint. A technical note

A modified posterior approach to the hip joint is described with particular applicability to revision or complex primary hip arthroplasty. The procedure involves osteotomy of the posterior one-third of the greater trochanter with posterior reflection of a full-thickness flap, consisting of the posterior trochanteric fragment, short external rotators, joint capsule, and posterior portion of the gluteus medius. The approach allows for excellent exposure of the acetabulum and femoral canal, with minimal disruption of the gluteal muscle insertions. The majority of the greater trochanter is left intact, enhancing femoral component stability. Closure is accomplished by suture of soft tissues and reattachment of the posterior trochanteric fragment with bone screws. An intact soft tissue envelope is thereby restored around the prosthetic components. A limited clinic series has identified no problem referable to this exposure. No loss of reduction or nonunion has been encountered.

Proteinase B is, indeed, not required for chitin synthetase 1 function in Saccharomyces cerevisiae

Previous genetic evidence led to the conclusion that proteinase B of yeast was not involved in the function of chitin synthetase 1 (Chs1), based on the demonstration of normal septum formation, cell division and chitin deposition in mutants devoid of the proteinase (Zubenko, G.S., Mitchell, A.P., and Jones, E.W. (1979) Proc. Natl. Acad. Sci. USA 76, 2395-2399). Later, however, it was found that the essential enzyme for septum formation is chitin synthetase 2, whereas Chs1 acts as an auxiliary enzyme, whose absence results in daughter cell lysis under acidic conditions (Cabib, E., Sburlati, A., Bowers, B. and Silverman, S.J. (1989) J. Cell Biol. 108, 1665-1672). By using the lytic behavior as a criterion, we have now found that prb1 strains are not defective in Chs1 function. Certain strains contain a recessive suppressor of lysis which could mask the Chs1 defect. However, appropriate crosses and transformation experiments showed that the prb1 mutants do not harbor the suppressor. It may now be concluded with confidence that proteinase B is not required for chitin synthetase 1 function.

Tetanus toxin-induced seizures cause microglial activation in rat hippocampus

Tetanus toxin (about 20 mouse LD50) injected into the ventral hippocampus of rats leads to brief seizures occurring intermittently over a period of weeks. Toxin injection leads to the appearance of activated microglia (detected with OX42 immunohistochemistry) in the hippocampus. After 7-14 days, many activated microglia are visible in CA1 area of dorsal hippocampus aligned with the pyramidal cell dendrites and having the morphology characteristic of 'rod cells'. Extensive cell loss is found in dorsal CA1, but not at the injection site, in about one third of injected rats.

Threaded acetabular components for primary and revision total hip arthroplasty

A clinical and radiographic review of 48 total hip arthroplasty patients with threaded acetabular components was undertaken at 24-44 months of follow-up study. Twenty-five patients had primary hip arthroplasties and 23 had revision procedures. Clinical scores revealed good to excellent results in 60% of primary and 30% of revision procedures. Radiographic analysis revealed stable acetabular components in 88% of primary and 61% of revision procedures. Potentially loose acetabular components were noted in 8% of primary and 4.3% of revision procedures and loose acetabular components in 4% of primary and 34.7% of revision procedures. The rate of acetabular component loosening was considered unacceptably high in revision cases and an area of concern in primary cases. Discretionary use of these components is advised.

Ulnar styloid fixation in the treatment of posttraumatic instability of the radioulnar joint: a biomechanical study with clinical correlation

Biomechanical displacement testing was done on nine fresh human upper extremities to define the stabilizing influence of the triangular fibrocartilage on the radioulnar joint and the efficacy of triangular fibrocartilage-ulnar styloid avulsion fracture repair in restoring lost stability. Test data confirmed that the triangular fibrocartilage is a major stabilizer of the radioulnar joint and internal fixation of triangular fibrocartilage-ulnar styloid avulsion fractures can restore preavulsion stability in all positions of forearm rotation. On the basis of this data and a successful clinical experience, primary repair of displaced ulnar styloid avulsion fractures is advised as a means of stabilizing the radioulnar joint and preventing the disability associated with chronic radioulnar joint instability.

Islet cell neoplasms. A fine-needle aspiration cytology study with immunocytochemical correlations

Islet cell neoplasms (ICNs) are uncommon tumors that may present with bizarre endocrine manifestations. Only rarely have their fine-needle aspiration (FNA) cytomorphologic characteristics been reported. The authors have studied FNAs of ICNs in ten patients, including immunocytochemistry (ICC) directly on the aspirates. FNA yielded moderately to markedly cellular specimens with numerous individual cells and large aggregates. Although moderate pleomorphism was present in three cases, striking uniformity in nuclear size and contour and in delicate nuclear membranes was evident. Typically the round nuclei were eccentric, imparting a plasmacytoid appearance. Cytoplasmic granularity was noted in only a minority of tumor cells. Five of the ICNs were positive for chromogranin (CG). In comparison, seven ICNs were positive for CG in tissue sections. None of the cytologic material showed immunoreactivity with insulin, glucagon, somatostatin, or gastrin. Histologic material showed positivity for these hormones in 33% (three of nine), 22% (two of nine), 22% (two of nine), and 11% (one of nine), respectively. Although CG is the most useful immunocytochemical marker for ICNs, and thus is helpful in confirming a diagnosis of ICN in FNA material, it is negative in half of the cases and may be negative when the histologic material is positive.

Primary bipolar total hip arthroplasty

A retrospective clinical and radiographic review of 140 primary total hip arthroplasties using a bipolar acetabular component and an uncemented AML femoral component (Depuy, Warsaw, IN) was done. The length of follow-up was from 2 to 5 years with a mean of 44.2 months. A mean postoperative Harris hip score of 84.3 points and a mean postoperative Harris pain score of 38.8 points were identified. Five hips required revision surgery, three for recurrent dislocations and two for infection. Nine percent of acetabular components were noted to have migrated within the bony pelvis by 2 mm or more. However, the presence of migration was not statistically associated with low pain or function scores. Ninety-eight percent of patients with surviving implants felt satisfied with the results of their surgery. Total hip arthroplasty using a bipolar acetabular component appears to be a successful method of hip replacement.

Characterization of the inverted duplication in the mitochondrial DNA of Candida albicans

The mitochondrial DNA (mtDNA) of Candida albicans contains a large inverted duplication. As is the case with most chloroplast DNAs and one other mtDNA, the nonduplicated regions of the molecule occur in two orientations with respect to each other, indicating that internal recombination occurs. Like some other mtDNAs, the C. albicans mtDNA contains a single SalI restriction site located near one end of the large rRNA gene. In contrast to other cases, however, the inverted duplication does not appear to contain any sequences coding for rRNA.

Total knee arthroplasty using the kinematic rotating hinge prosthesis

Patients receiving a Kinematic Rotating Hinge total knee prosthesis with a 25-month minimum follow up were reviewed. A total of 46 patients and 54 knees were included in the study. A detailed clinical assessment was available on 38 knees. Twenty of these knees had primary arthroplasties performed with the Kinematic Rotating Hinge prosthesis and 18 knees had revision arthroplasty. Ninety-five percent of primary knees and 83% of revision knees caused no or mild pain postoperatively. Using the Brigham and Women's Hospital and Harvard Medical School knee rating system, 80% of primary knees and 61% of revision knees were rated as good to excellent. Using the criteria defined in this article, 90% of primary knees and 83% of revision knees were labeled as having a satisfactory result. Forty-five percent of primary components and 52% of revision components demonstrated lucent lines on radiographic review. Seven percent of primary knees and 20% of revision knees showed evidence of aseptic lucency progression in one or more zones. No radiographic evidence of aseptic loosening was noted in this review. Documented sepsis occurred in one primary knee and two revision knees. Patellar instability occurred in 21% of primary knees and 36% of revision knees, representing the major complication. The Kinematic Rotating Hinge prosthesis is intended for use in arthroplasty cases where there is functional absence of collateral ligament stability. This review suggests that a high percentage of satisfactory clinical results can be achieved with this prosthesis with long-term radiographic stability.

Extensor digitorum brevis manus muscle. A clinical reminder

The extensor digitorum brevis manus is an aberrant finger extensor occurring on the dorsum of the hand. This anomalous muscle is easily mistaken for other dorsal hand pathology. An awareness of its existence is the basis for clinical diagnosis and appropriate treatment.

Compression capability of cerclage fixation systems. A biomechanical study

Cerclage wire or tension band techniques are frequently complicated by broken wires or inadequate bony stabilization. The fixation capabilities of various cerclage systems were defined in this study by measuring the maximum compression forces generated by the different methods as well as their ultimate strengths. Parham bands and swage-lock titanium cables were found to exhibit the greatest fixation potential and highest ultimate strengths. Cerclage fixation using stainless steel wire was found to be enhanced by using a modified square knot. Mersilene tape was found to have fixation capabilities of similar magnitude to 20 guage stainless wire secured with a twist knot. The polypropylene and nylon cable ties tested showed no advantage when compared to the other systems.

Childhood depression

The spectrum of depressive disorders found in children and adolescents presents diagnostic and treatment challenges for the physician. The increasing scientific rigor of child and adolescent mental disorder research has explicated the importance of clinical diagnoses. Distinctions have to be made between depressive symptoms that are transient and situational specific and the constellation of depressive symptoms that represent clinical disorders such as bipolar disorder, cyclothymia, major depressive disorder, or dysthymia. The clinically sensitive physician attuned to the diagnostic criteria of these disorders has the opportunity to promote effective treatment and to reduce the morbidity associated with these conditions. The established severity and persistence of these disorders over time suggests the need for definitive medical management of these conditions. The recognition of childhood depression as a medical entity of varying severity, persistence, and prognosis represents the first step in effective treatment.

AML bipolar arthroplasty for degenerative hip arthritis

Primary total hip arthroplasty using an uncemented AML porous coated femoral component and a bipolar acetabular component was performed on 50 consecutive patients with degenerative arthritis. Of the 50 patients, 43 (48 hips) were available for review at 2 to 3 years follow up. The data obtained in this review suggest that total hip arthroplasty using this prosthesis provides a consistently reliable hip replacement with few related complications and a high patient satisfaction rate. A stable radiographic appearance of both the femoral and acetabular components can be expected.

A biomechanical comparison of scaphoid screws

The compressive forces generated by various scaphoid screws were measured in the laboratory using a custom designed load washer (transducer) as a means to compare their fixation capabilities. Testing was done using simulated bones fabricated from polystyrene pipette tubing and Pedilen polyurethane foam and paired cadaver scaphoids. The Herbert scaphoid screw was found to have inferior fixation capabilities compared with screws of a more conventional design. However, its size compatibility was the best of all the screws tested. The Heune scaphoid screw demonstrated the best fixation capability, but was found to be too large for routine use. The ASIF cancellous screw (4.0 mm) demonstrated excellent fixation capability, but was believed to have too large a head size for many scaphoids. An optimal screw design is proposed for use in scaphoid fractures based on failure data for various thread sizes and head diameters.

Triple antibiotics for the treatment of infected joint replacements. Case report and commentary

Combination antibiotics are frequently used in the treatment of infected joint arthroplasties to achieve synergistic activity against the infecting organisms. A case is presented in which triple antibiotic therapy was used in the treatment of an infected hip arthroplasty. The antibiotic combination proved to have an antagonistic effect despite documented sensitivities to the individual drugs. Serum antimicrobial assays are recommended in the treatment of all prosthetic joint infections.

Osteoid osteoma of the lunate

Osteoid osteoma is a rare lesion in the carpus. This article records the case of an osteoid osteoma occurring in the lunate.