The effect of tubularization on the mechanical properties of patellar tendon grafts.

To determine the effect of tubularization on the prefailure mechanical properties of bone-patellar tendon-bone autografts used for anterior cruciate ligament repair, 10 bovine bone-patellar tendon-bone grafts were tested in tension before and after tubularization with running suture. The testing protocol involved a 5-N preload, 10 preconditioning cycles to 200 N, and a final test cycle to 950 N at 1000 N/sec. Five of the grafts were tested first as harvested (flat) and then again following tubularization. The remaining five grafts were tubularized prior to the initial testing, and final testing was done with the suture removed. Raw testing data were reduced to determine the amount of stretching associated with preconditioning, as well as laxity and stiffness of the preconditioned grafts. Tubularized grafts stretched significantly more than flat grafts during preconditioning: 3.5 times as much after the first preconditioning cycle (3.8+/-1.9 mm versus 1.1+/-0.78 mm) and 3.1 times as much after 10 cycles (5.0+/-2.1 mm versus 1.6+/-0.9 mm). There was no statistically significant difference in the stiffnesses of the tubularized and flat grafts, nor did tubularization have an effect on graft laxity. Interestingly, there was a slight increase in laxity the second time each graft was tested, regardless of whether the graft was flat or tubularized when it was first tested. These results highlight the importance of preconditioning patellar tendon grafts before fixation, especially those that have been tubularized.

Lowering of p27Kip1 levels by its antisense or by development of resistance to 1,25-dihydroxyvitamin D3 reverses the G1 block but not differentiation of HL60 cells.

Cyclin-dependent kinase inhibitors are proteins with functions which appear to involve regulation of cell cycle traverse, and have been suggested to have a role in cell differentiation. However, there is as yet no rigorous proof that this is the case. We have addressed the participation of one of these inhibitors, p27Kip1, in the induction of differentiation and the subsequent G1 block induced in HL60 cells by 1,25-dihydroxyvitamin D3 (1,25D3). First, it was noted that sublines of HL60 cells able to grow rapidly in the presence of 1,25D3 have protein levels of p27Kip1 lower than the levels in cells subjected to 1,25D3-induced growth inhibition, but higher than in untreated parental cells. In contrast, there was no discernible relationship between the levels of p27Kip1 and the expression of differentiation markers. Further, HL60 cells treated with 1,25D3 and an oligonucleotide antisense, but not mismatched, to p27Kip1 showed an almost complete elimination of the 1,25D3-induced G1 block, but no decrease in the expression of differentiation markers. Similar results were obtained following transient transfection with an expression vector bearing the entire p27Kip1 coding sequence in the anti-sense orientation. This is the first direct demonstration that p27Kip1 plays a role in the 1,25D3-induced G1 arrest, and that partial reduction in its levels has no effect on the induction of differentiation in HL60 cells.

Scapholunate ligament reconstruction using a bone-retinaculum-bone autograft: a biomechanic and histologic study.

A new surgical technique has been recently described that involves reconstruction of the dorsal aspect of the scapholunate ligament (DSLL) with a bone-retinaculum-bone (BRB) autograft preparation from Lister's tubercle. In this study, the mechanic and histologic properties of the 2 tissues were compared. The BRB and DSLL specimens were harvested from 6 fresh-frozen human cadaveric forearms. The specimens were measured and then tested in tension with an MTS 810 servohydraulic materials testing machine at a rate of 10 mm/min. The BRB autograft was significantly weaker than the DSLL. However, because the mean cross-sectional area of the DSLL was more than 3 times as large as that of the BRB autograft, the failure stress (failure force/cross-sectional area) of the BRB autograft was not significantly different from that of the DSLL. Histologically, the DSLL and BRB autograft were also similar. These findings suggest that the BRB autograft may be appropriate graft material for scapholunate ligament reconstruction, but that structural parity with DSLL will ultimately depend on remodeling and hypertrophy during healing. This also highlights the importance of using a large BRB autograft to approximate the strength of the DSLL as much as possible, and that the BRB autograft must be protected postoperatively as it heals and remodels.

Restoration of pedicle screw fixation with an in situ setting calcium phosphate cement.

STUDY DESIGN: Pedicle screws were pulled out of human cadaveric vertebrae before and after augmentation with polymethylmethacrylate or in situ-setting calcium phosphate cement. The fixation strength of screws augmented with calcium phosphate cement was compared with that of screws augmented with polymethylmethacrylate. OBJECTIVES: To determine whether a new in situ-setting calcium phosphate cement might be suitable for augmenting the fixation of pedicle screws. The principle objective was to compare the pull-out resistance of screws augmented with calcium phosphate cement with the pull-out behavior of screws augmented with polymethylmethacrylate. Polymethylmethacrylate augmentation was chosen as the standard because of its current clinical use. Five types of screws were tested to determine whether screw design had an effect on the efficacy of augmentation. SUMMARY OF BACKGROUND DATA: Although many factors affect the pull-out resistance of pedicle screws, a key determinant of their performance is the strength of their attachment to the spine. In elderly, osteopenic patients, the screw-bone interface is especially at risk for stripping during insertion or pull-out after surgery. In these patients, polymethylmethacrylate has been used to augment pedicle screw fixation, although its use is not without risk. In situ-setting calcium phosphate cements may provide an alternative to polymethylmethacrylate in this application. Like polymethylmethacrylate, calcium phosphate cements can be injected into the prepared screw hole. They have the added advantage of being resorbed and replaced during healing and normal bone remodeling. METHODS: Thirty human lower lumbar vertebrae (L3-L5) were implanted bilaterally with one of five types of pedicle screws (n = 6 for each screw type). The screws were pulled out 3.0 mm at 0.25 mm/sec with a servohydraulic materials testing machine. The 3.0-mm pull-out distance, which was slightly longer than one thread pitch, was designed to strip the screw-bone interface but to leave the pedicle otherwise intact. After the initial testing, the screws in each vertebrae were removed, and the screw tracks were filled with 2.0 cc of polymethylmethacrylate (one side) or calcium phosphate cement (contralateral side). After augmentation, the screws were reinserted, and the cements were allowed to harden for 24 hours. Postaugmentation testing followed the protocols for preaugmentation testing, and the pull-out resistance of screws augmented with calcium phosphate cement was compared with the pull-out resistance of screws augmented with polymethylmethacrylate. RESULTS: Mechanically, calcium phosphate cement compared favorably with polymethylmethacrylate for augmenting pedicle screws. Both restored the strength of the screw-bone interface: across all screw types, the average increase in pull-out strength was 147% with polymethylmethacrylate augmentation and 102% with calcium phosphate cement. There were no significant differences because of screw type with either type of augmentation. CONCLUSIONS: The in situ-setting calcium phosphate cement investigated in this study compared favorably with polymethylmethacrylate in a single-cycle, pull-out test of augmented pedicle screws in senile trabecular bone. With further evaluation, this cement may offer an alternative to polymethylmethacrylate for the enhancement of pedicle screw fixation clinically.

Detection of human papillomavirus in cervical biopsies of summer camp ROTC cadets with abnormal papanicolaou smears.

STUDY OBJECTIVE: Human papillomavirus (HPV) infections may be the most common sexually transmitted disease (STD) among adolescents and young adults. A strong association exists for certain "high-risk" HPV-type cervical infections and subsequent evolution of cervical cancer and its precursor lesions. The objective of this study was to detect HPV in cervical biopsies of reserve officer training corps (ROTC) cadets attending a regional summer camp who had abnormal screening Papanicolaou (Pap) smears and to better define the spectrum of HPV oncogenic risk types for this population. It was hypothesized that HPV would be detected in the majority of cervical biopsies in keeping with the evolving concept of cervical cancer and its precursors as an STD and the central role of HPV in its development. DESIGN: On arrival for summer military camp training, college women cadets underwent physical examinations that included pelvic examinations for Pap smears. Study participants completed confidential questionnaires after informed consent was obtained. Subjects, who had abnormal Pap smears as defined by reports of atypical squamous cells of undetermined significance (ASCUS) or low- or high-grade squamous intra-epithelial lesions (LGSIL or HGSIL), underwent colposcopic evaluations with cervical biopsies. Subsequently, biopsies were processed for detection of HPV-specific DNA by gel electrophoresis, chemiluminescent oligonucleotide probing, and DNA-RNA hybridization methods after polymerase chain reaction (PCR) amplification. PARTICIPANTS: All female summer camp enrollees presented to the Madigan Army Medical Center Gynecology Clinic for complete physicals before the onset of the training program and were solicited for study inclusion. MAIN OUTCOME MEASURES: All colposcopic biopsy specimens were evaluated for the presence of HPV DNA and subtyped if positive. RESULTS: Representing 42 states, 95% (332) of eligible subjects participated. Mean age was 21.9 years. Racial composition included 70% white, 16% black, 4% Hispanic, 4% Asian, and 6% "other." Eighty-five percent had a history of hetero-sexual activity, with 17.7 years as the mean age at onset. Of the subjects, 12.6% reported a previous diagnosis of a sexually transmitted disease, and 7.8% (26 of 332) had abnormal Pap smears. Of these, colposcopic biopsy results were available for 25 of the 26 abnormal Pap smears. Ninety-six percent (24 of 25) of the colpobiopsies had detectable HPV. Eighty-eight percent (22 of 25) of the subjects with abnormal Pap smears had concurrent abnormal biopsy results. All of these had detectable HPV, confirmed by three different methods, and 29% had dual HPV infection. Sixty percent had "intermediate" or "high-risk" types identified by specific genotyping, 8% had "low-risk" types, and 28% had nontypable HPV. CONCLUSIONS: The data confirm that abnormal Pap smears in this young adult college population are almost always associated with HPV infection, a significant proportion of it being other than low-risk types. The prognostic significance of type-specific cervical HPV infection still needs to be better defined in relation to potential cofactors and host immune response. However, clinicians who provide primary gynecologic care to adolescents and young adults should be aware of the high correlation between abnormal Pap smears and HPV cervical infection and should follow up the patient with the potential risk in mind.

Anatomy of the palmar cutaneous branch of the median nerve: clinical significance.

A detailed anatomic, histologic, and immunohistochemical study of the palmar cutaneous branch of the median nerve (PCBMN) and its distal arborization was undertaken on 12 fresh human cadaveric hands. Small unmyelinated fibers terminated in the superficial loose connective tissue of the transverse carpal ligament. There were no nerve fibers detected in the deep, dense collagen aspect of the ligament. Based on these findings, during open carpal tunnel release, the skin incision should be placed along the axis of the ring finger to avoid injury to the superficial branches of the PCBMN. When open release is used, the very small terminal branches in the loose tissue of the ligament will be transected; this may in part be responsible for postoperative soft tissue pain. For endoscopic releases, some risk for transection of the main trunk of the PCBMN at the proximal incision exists. Repeated passes of the endoscopic knife should be avoided in an attempt to limit damage to the small fibers in the superficial aspect of the ligament.

Natural course of 'subclinical' hypothyroidism in childhood and adolescence.

OBJECTIVES: To describe the natural course of "subclinical" hypothyroidism due to autoimmune thyroiditis in children and adolescents, and to determine whether, like euthyroid childhood autoimmune thyroiditis, it would also run a more benign course in this age group than in adults. DESIGN: Case series. SETTING: Pediatric endocrine clinic in a tertiary medical center. PATIENTS: Eighteen patients (age range, 5 to 19 years) with juvenile autoimmune thyroiditis and an initially elevated serum thyrotropin (thyroid-stimulating hormone) concentration were followed up from documentation of the elevated serum thyrotropin concentration for a mean of 5.8 years. Eleven patients never received treatment, and seven were followed up after discontinuation of therapy. MAIN OUTCOME MEASURES: Changes in the serum thyrotropin and thyroxine concentrations and thyroid gland size, as well as signs and symptoms of hypothyroidism, were monitored throughout the observation period. RESULTS: The mean duration of observation during which the patients did not receive any therapy was 47.3 months. At the end of the observation period, seven patients were euthyroid, 10 continued to have an elevated serum thyrotropin concentration with a normal serum thyroxine concentration, and one became hypothyroid. CONCLUSIONS: "Subclinical" juvenile hypothyroidism may be a benign and remitting process in many older children and adolescents. In view of the undefined risks of levothyroxine sodium therapy, it may be possible to follow up expectantly selected younger patients with a minimally elevated serum thyrotropin concentration, rather than to treat them empirically.

Sunlight--can it prevent as well as cause cancer?

Excessive exposure to sunlight is known to damage the skin. However, the emphasis of most studies has been on the consequences of sunlight exposure to fair-skinned individuals, and the situation of people with heavy skin pigmentation residing in, or migrating to, geographic locations with limited sunlight incidence has been largely neglected. Recent epidemiological studies suggested the hypothesis that sunlight deprivation, and the associated reduction in the circulating levels of vitamin D3 (vit D3) derivatives may lead to the increased incidence of the carcinomas of the breast, colon, and prostate. Two endocrine pathways may mediate these effects. The pineal function can potentially be involved, but the formation of vit D3 derivatives is gaining credibility as a mechanism for the retardation of cancer progression. Evidence is accumulating that such compounds, e.g., 1,25-dihydroxyvitamin D3 (1,25D3) induce differentiation of several neoplastic cell types, arrest or retard their proliferation, and act as chemopreventive agents in animal carcinogenesis. We also propose that the antineoplastic effects of vit D3 derivatives are exerted at several steps in tumor progression and that immunomodulating effects of 1,25D3 may contribute to these effects of sunlight. The recent findings that common cancers, e.g., carcinoma of the prostate and the breast, behave more aggressively in black Americans than in white Americans may be explained on this basis. Although more data are needed on the effects of sunlight on the circulating levels of 1,25D3, a corollary of this hypothesis is that there should be no broad condemnation of moderate sunlight exposure, as it may be available in insufficient amounts to some Americans.

Hypothalamic hamartoma in oral-facial-digital syndrome type VI (Váradi syndrome).

Oral-facial-digital syndrome (OFDS) type VI (Váradi syndrome) is an autosomal recessive trait of orofacial anomalies, cerebellar dysgenesis, and polysyndactyly. Developmental anomalies of the posterior fossa, including cerebellar hypoplasia and variants of the Dandy-Walker complex, are the most common central nervous system malformations reported in patients with this syndrome. We report hypothalamic hamartoma, supernumerary maxillary incisor, and precocious puberty in a boy with OFDS type VI. We propose that hypothalamic hamartoma is an occasional manifestation of OFDS type VI.

Inhibition by 1,25 dihydroxyvitamin D3 of c-myc down-regulation and DNA fragmentation in cytosine arabinoside-induced erythroid differentiation of K562 cells.

The effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on DNA fragmentation, altered expression of the heat shock protein (hsp) 70 gene, and protooncogenes c-myc and c-myb was studied during chemical induction of erythroid differentiation in K562 cells. Preincubation of K562 cells with 1,25(OH)2D3 did not alter the concentration of hemoglobin in cells which did differentiate, but led to a reduction in the accumulation of low molecular weight DNA generated by Ara-C administration. The extent of this reduction was similar to the degree of inhibition of hemoglobin formation in the culture as the whole. Preincubation with 1,25(OH)2D3 had no effect on the increase of hsp 70 gene expression induced by a 48-hr treatment with Ara-C, but prevented the Ara-C-induced down-regulation of the protooncogene c-myc. The protooncogene c-myb was down-regulated after 15 min of treatment with Ara-C, and exposure to 1,25(OH)2D3 prior to Ara-C caused a further down-regulation of its expression. The data suggest that the events associated with erythroid differentiation may be separable into at least two groups; one of these may have an influence on the kinetics of the cell cycle traverse, and the other may be related to the expression of the erythroid phenotype.

Gynaecomasty as the first manifestation of sexual precocity (case report).

We report on a young boy who developed gynaecomastia 15 months before he showed clinical manifestations of sexual precocity. He was treated with medroxyprogesterone acetate with good results. His development to adulthood is presented. The causes of gynaecomastia in the prepubertal child are reviewed.

Vitamin D analogs inhibit erythroid differentiation and induce monocytic differentiation of leukemic cells with the same relative potency.

Myeloid leukemia cells of human and murine origin can be induced to differentiate into more mature forms which lose their neoplastic properties. The hormonal form of vitamin D is a powerful inducer of monocytic differentiation, but its therapeutic use is limited by hypercalcemia. It was recently reported that a novel derivative of vitamin D, 1,25-dihydroxy-16-ene-23-yne-vitamin D3, is an exceptionally potent inducer of monocytic differentiation, and prolongs survival of mice bearing leukemia cells. We now show that this compound is also a most potent inhibitor of erythrodifferentiation. This finding has important implications for the control of hematopoiesis.

Association of c-myc protein with enzymes of DNA replication in high molecular weight fractions from mammalian cells.

Oncoprotein c-myc is expressed in proliferating but not quiescent mammalian cells, and its overexpression or inappropriate expression is associated with malignant transformation. However, in spite of an intense interest, the normal function of this protein has remained elusive. As a step towards the elucidation of the function of c-myc protein, we studied its distribution within several types of cells, including HL 60, K 562, COLO 320, and CHEF/18 cells. In all of the cells studied, c-myc protein was detected in high molecular weight protein fractions, in 350-600 Kd range, in gel-exclusion chromatography and sucrose gradient centrifugation. This distribution of c-myc protein coincided with the distribution of DNA polymerase alpha and several other enzymes necessary for DNA replication. The data suggest that c-myc product may be a component of the replitase complex of enzymes involved in nuclear DNA replication.

Autogeneic bone marrow and porous biphasic calcium phosphate ceramic for segmental bone defects in the canine ulna.

The purpose of this study was to evaluate a porous biphasic hydroxyapatite-calcium phosphate ceramic as a modifier and extender of an autogeneic marrow graft for filling a 2.5-cm segmental bony defect. Twenty adult mongrel dogs were surgically treated to create diaphyseal defects in the left ulnae. The defects were (1) filled with autogeneic bone marrow mixed with granular hydroxyapatite-tricalcium phosphate ceramic (granular ceramic); (2) grafted with a solid block of ceramic soaked in autogeneic bone marrow (block ceramic); (3) received no graft (no implant); or (4) were grafted with autogeneic bone marrow alone (bone marrow). All animals were followed clinically and roentgenographically for 24 weeks and then killed. Repair of diaphyseal defects with the block ceramic led to three solid unions and three fibrous unions; with the granular ceramic implants and marrow, the defects of five dogs formed solid unions, and one progressed to a fibrous union. Defects in all five dogs grafted with autogeneic bone marrow united. The three dogs with no implant formed nonunions. Histology showed normal marrow and only a light immune reaction. Complete bridging of the defect in the dogs treated with the granular ceramic occurred significantly earlier than bridging in the dogs grafted with bone marrow alone. Histomorphometry, performed on the block ceramic implants indicated active resorption of ceramic. Clinically, addition of ceramic to a marrow graft improved the handling characteristics of the graft material and accelerated healing according to roentgenographic evaluation.

Inhibition by 1,25 dihydroxyvitamin D3 of chemically induced erythroid differentiation of K562 leukemia cells.

The physiologically active form of vitamin D, 1,25 dihydroxyvitamin D3 [1,25(OH)2D3], was found to inhibit erythroid differentiation of human leukemic K562 cells. Differentiation was induced by 1 mumol/L arabinocytosine (Ara-C), 40 mumol/L tiazofurin, 1 mumol/L aphidicolin, or 1 mumol/L hydroxyurea, and was monitored daily by the appearance of hemoglobin in an increasing proportion of cells. Pretreatment for 48 hours with 2.4 x 10(-8) mol/L 1,25(OH)2D3, a concentration that is also optimal for induction of monocytic differentiation of HL-60 cells, reproducibly inhibited subsequent induction of erythroid differentiation by all of the above inducers, and modified the morphologic changes that Ara-C produced in these cells. The inhibition of hemoglobinization was approximately 50% irrespective of the degree of differentiation produced by the various inducers, but growth inhibition associated with exposure to the inducers was not affected by 1,25(OH)2D3. Similar inhibition of differentiation by 1,25(OH)2D3 was observed in mouse erythroleukemia cells MEL-D1B treated with 5 mmol/L hexamethylenebisacetamide. The inhibitory effect of 1,25(OH)2D3 on erythroid differentiation of K562 cells was abrogated by cyclohexamide (20 micrograms/mL), an inhibitor of protein synthesis. The mRNA for 1,25(OH)2D3 receptor (VDR) was detected in K562 cells, and was downregulated by a 96-hour exposure to 1,25(OH)2D3 or a 48-hour exposure to Ara-C. The presence of VDR mRNA suggests a physiologic role for 1,25(OH)2D3 in K562 cells that are precursors of erythroid cells. This role is perhaps to shift the pathways of differentiation from the erythroid to the monocytic lineage.

Intralenticular abscess.

Intralenticular abscess is an uncommon complication of surgery or trauma. A case of intralenticular abscess following penetrating trauma is presented. In this case, the offending organism was identified as Propionibacterium acnes. This organism is considered to be a cause of slowly progressing endophthalmitis and has been implicated as a cause of the so-called toxic lens syndrome.

Morphometric analyses of changes in cell shape in the neuroepithelium of mammalian embryos.

During neurulation the elevation of the neural folds is accompanied by, and thought to be partly driven by, changes in the shapes of the neuroepithelial cells. This paper explores the use of form factors for the measurement of changes in cell shape during normal and perturbed neural fold elevation in rat embryos; it is the first attempt to quantify changes in the shapes of cells during neurulation in mammalian embryos. Rat embryos at 9.9 days of gestation, when the neural epithelium is a biconvex plate, and at 10.4 days of gestation, when the cervical neural epithelium has formed the neural tube and when the cephalic neural folds have elevated but not fused, were used. In addition, embryos in which the cephalic neural folds had been caused to re-open by culture in saline with low calcium were examined. Embryos were fixed and then fractured across the neural axis. A montage of the fractured edge of the neuroepithelium was prepared from a series of scanning electron micrographs. Cells of the neuroepithelium were classified according to the shapes of their profiles as rectangular, round, apically tapered, basally tapered or spindle-shaped, the last three categories being considered as 'tapered'. The outlines of the cells were digitised using a computer-linked graphics tablet to provide estimations of the perimeters (p) and areas (a) of the cell profiles, and the form factors, f. of the cell profiles were calculated by f = 4 pi a/p2. This factor is a unitless ratio which is unity for a circle and less than unity for any other shape. It provides a measure of the efficiency with which a perimeter encloses an area, and thus indicates the degree of deformation of a shape from circular. From 9.9 to 10.4 days the cervical neuroepithelium shows a decrease in the percentage of rectangular cells and an increase in the percentage of spindle-shaped cells. The mean form factors of cells in the apically tapered and spindle-shaped categories decrease, showing that these cells are more elongated and tapered in later embryos. When embryos at 10.4 days are cultured in saline with low calcium the elevated cephalic neural folds collapse. Concomitantly the percentage of round cells in the cephalic neural folds increases and the percentage of apically tapered and spindle-shaped cells decrease.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of mannose on rat embryos grown in vitro.

Rat embryos have been cultured in vitro from 9.5 days of gestation for different times in serum containing mannose, and the embryos have been observed by scanning electron microscopy. Embryos cultured in 3 mg/ml (1.7 X 10(-2) M) or 6 mg/ml (3.3 X 10(-2) M) mannose for 48 h showed inhibition of the expansion of the yolk sac and were smaller than the control embryos. Mannose-treated embryos also showed delayed development according to morphological criteria, and a range of abnormalities including abnormalities of the neural tube. Embryos cultured in 6 mg/ml mannose for 24 h also showed significant inhibition of yolk-sac expansion and were smaller and less advanced than the control embryos. Abnormalities were seen, including a delay in the closure of the neural folds. Abnormalities were also observed in embryos cultured in mannose for 10 h; embryos at the neural groove stage showed irregularities in the neural groove. Mannose did not inhibit the re-elevation of neural folds which had been caused to collapse by exposure to medium containing low calcium. These results are compatible with the idea that mannose retards development and thereby perturbs the morphogenesis of the neural tube.