Reliability of the sourcil method of acetabular index measurement in developmental dysplasia of the hip

PURPOSE

The ability to monitor and study developmental dysplasia of the hip (DDH) requires validated radiographic outcome measures. The sourcil method of acetabular index measurement (AI-S) has not yet been shown to be a reliable measure of acetabular dysplasia in a DDH population, despite its widespread use. The aims of this study were to test the reliability of the AI-S method in a DDH population, and to compare the reliability of the AI-S method with that of the classic lateral edge method (AI-L).

METHODS

From an institutional database, standardized anteroposterior hip radiographs were obtained from a cohort of 35 female patients (70 hips) at two and five years of age who had been treated nonoperatively for DDH. Three observers independently measured the acetabular index using the AI-L and AI-S methods on all 70 hips at two time points, four weeks apart.

RESULTS

The inter-rater reliability intraclass correlation coefficient (ICC) for the AI-L and AI-S methods was between good and excellent at 0.94 (confidence interval (CI) 0.89 to 0.96) and 0.91 (CI 0.87 to 0.94), respectively. The ICCs for intra-rater reliability for the AI-L method were excellent at 0.93 (CI 0.90 to 0.95), 0.95 (CI 0.93 to 0.97) and 0.95 (CI 0.94 to 0.97) for raters 1, 2 and 3, respectively. The ICCs for intra-rater reliability for the AI-S method were between good and excellent at 0.91 (CI 0.87 to 0.93), 0.93 (CI 0.90 to 0.95) and 0.90 (CI 0.86 to 0.93) for raters 1, 2 and 3 respectively.

CONCLUSION

Both AI-S and AI-L methods are equally reliable radiographic measures of DDH.

LEVEL OF EVIDENCE

Level III (diagnostic).

The incidence of avascular necrosis and the radiographic outcome following medial open reduction in children with developmental dysplasia of the hip: a systematic review

The incidence of clinically significant avascular necrosis (AVN) following medial open reduction of the dislocated hip in children with developmental dysplasia of the hip (DDH) remains unknown. We performed a systematic review of the literature to identify all clinical studies reporting the results of medial open reduction surgery. A total of 14 papers reporting 734 hips met the inclusion criteria. The mean follow-up was 10.9 years (2 to 28). The rate of clinically significant AVN (types 2 to 4) was 20% (149/734). From these papers 221 hips in 174 children had sufficient information to permit more detailed analysis. The rate of AVN increased with the length of follow-up to 24% at skeletal maturity, with type 2 AVN predominating in hips after five years' follow-up. The presence of AVN resulted in a higher incidence of an unsatisfactory outcome at skeletal maturity (55% vs 20% in hips with no AVN; p < 0.001). A higher rate of AVN was identified when surgery was performed in children aged < 12 months, and when hips were immobilised in ≥ 60° of abduction post-operatively. Multivariate analysis showed that younger age at operation, need for further surgery and post-operative hip abduction of ≥ 60° increased the risk of the development of clinically significant AVN.

Limb reconstruction using circular frames in children and adolescents with spina bifida

We report the outcome of 28 patients with spina bifida who between 1989 and 2006 underwent 43 lower extremity deformity corrections using the Ilizarov technique. The indications were a flexion deformity of the knee in 13 limbs, tibial rotational deformity in 11 and foot deformity in 19. The mean age at operation was 12.3 years (5.2 to 20.6). Patients had a mean of 1.6 previous operations (0 to 5) on the affected limb. The mean duration of treatment with a frame was 9.4 weeks (3 to 26) and the mean follow-up was 4.4 years (1 to 9). There were 12 problems (27.9%), five obstacles (11.6%) and 13 complications (30.2%) in the 43 procedures. Further operations were needed in seven patients. Three knees had significant recurrence of deformity. Two tibiae required further surgery for recurrence. All feet were plantigrade and braceable. We conclude that the Ilizarov technique offers a refreshing approach to the complex lower-limb deformity in spina bifida.

Deletion of the 5-HT(3A)-receptor subunit blunts the induction of cocaine sensitization

Serotonin (5-HT) receptors are classified into seven groups (5-HT(1-7)), comprising at least 14 structurally and pharmacologically distinct receptor subtypes. Pharmacological antagonism of ionotropic 5-HT(3) receptors has been shown to modulate both behavioral and neurochemical aspects of the induction of sensitization to cocaine. It is not known, however, if specific molecular subunits of the 5-HT(3) receptor influence the development of cocaine sensitization. To address this question, we studied the effects of acute and chronic intermittent cocaine administration in mice with a targeted deletion of the gene for the 5-HT(3A)-receptor subunit (5-HT(3A)-/-). 5-HT(3A) (-/-) mice showed blunted induction of cocaine-induced locomotor sensitization as compared with wild-type littermate controls. 5-HT(3A) (-/-) mice did not differ from wild-type littermate controls on measures of basal motor activity or response to acute cocaine treatment. Enhanced locomotor response to saline injection following cocaine sensitization was observed equally in 5-HT(3A) (-/-) and wild-type mice suggesting similar conditioned effects associated with chronic cocaine treatment. These data show a role for the 5-HT(3A)-receptor subunit in the induction of behavioral sensitization to cocaine and suggest that the 5-HT(3A) molecular subunit modulates neurobehavioral adaptations to cocaine, which may underlie aspects of addiction.

Combined mitochondrial and nuclear sequences support the monophyly of forcipulatacean sea stars

Previous molecular phylogenetic analyses of forcipulatacean sea stars (Echinodermata: Asteroidea) have reconstructed a non-monophyletic order Forcipulatida, provided that two or more forcipulate families are included. This result could mean that one or more assumptions of the reconstruction method was violated, or else the traditional classification could be erroneous. The present molecular phylogenetic analysis included 12 non-forcipulatacean and 39 forcipulatacean sea stars, with multiple representatives of all but one of the forcipulate families and/or subfamilies. Bayesian analysis of approximately 4.2kb of sequence data representing seven partitions (nuclear 18S rRNA and 28S rRNA, mitochondrial 12S rRNA, 16S rRNA, 5 tRNAs and cytochrome oxidase I with first and second codon positions analyzed separately from third codon positions) recovered a consensus tree with three well-supported clades (78%-100% bootstrap support) that corresponded at least approximately to traditional taxonomic ranks: the superorder Forcipulatacea (Forcipulatida + Brisingida) + Pteraster, the Brisingida/Brisingidae and Asteriidae + Rathbunaster + Pycnopodia. When a molecular clock was enforced, the partitioned Bayesian analysis recovered the traditional Forcipulatacea. Five of six genera represented by two or more species were monophyletic with 100% bootstrap support. Most of the traditional subfamilial and familial groupings within the Forcipulatida were either unresolved or non-monophyletic. The separate partitions differed considerably in estimates of model parameters, mainly between nuclear sequences (with high GC content, low rates of sequence substitution and high transition/transversion rate ratios) and mitochondrial sequences.

Blood ordering protocol based on proposed surgical implant in fractured neck of femur patients

INTRODUCTION

Fractured neck of femur patients frequently require blood transfusion. To improve the efficiency of blood ordering, we present a protocol which orders blood specific for the proposed surgical implant.

PATIENTS AND METHODS

A retrospective audit over a 1-year period was performed. Patients were divided into six groups dependent on proposed surgical implant. The mean postoperative drop in haemoglobin concentration, the cross-match to transfusion ratio and transfusion indexes were calculated.

RESULTS

Statistically significant differences in blood loss were found dependent on implant used. Using guidelines created by the British Committee for Standards in Haematology on the implementation of a maximum surgical blood ordering schedule, a new protocol for blood ordering based on proposed surgical implant was created.

CONCLUSIONS

In fractured neck of femur patients awaiting operation, the type of implant can be used to anticipate blood loss and as a guide to blood ordering.

Orthopaedic surgeons in Yorkshire--are we ATLS positive?

INTRODUCTION

In 1993, the Major Trauma Working Group of Yorkshire proposed that hospitals should be accredited as Trauma Reception Hospitals with a policy for the response to the arrival of a trauma patient. These requirements include specific criteria for orthopaedics.

METHODS

To evaluate if these criteria are being fulfilled, we carried out an audit comparing the response in the hospitals within the Yorkshire deanery to the arrival of major trauma. All consultant and middle-grade orthopaedic surgeons on call for trauma were contacted and questioned as to their ATLS provider status and involvement in the "trauma call".

RESULTS

16 hospitals were included of which 13 have a "trauma team". 191 surgeons (96% response) were included. 175 have completed an ATLS course. Of these, 72 (41%) had out-of-date qualifications. Only 9 (13%) were waiting to revalidate. Variation was seen in the frequency of accident and emergency department attendance by different grades of surgeon for major trauma.

DISCUSSION

All hospitals have a response for major trauma although variations occur. The vast majority of orthopaedic surgeons in Yorkshire have been adequately trained in ATLS management (more so than any study has previously shown), particularly the middle grades, who are usually first to attend. The level of revalidation is low and reasons for this are discussed with recommendations for revalidation in the future.

Axillary artery transection following anterior shoulder dislocation: classical presentation and current concepts

Injury to the axillary artery following anterior shoulder dislocation is a very rare occurrence. This review serves to illustrate the now classical case of an elderly gentleman with a recurrent dislocation, transection of the axillary artery and its invariable association with a severe brachial plexus lesion, which is the most important determinant of long-term disability. It also highlights the pathognomic triad of anterior shoulder dislocation, expanding axillary haematoma and diminished peripheral pulse, to highlight awareness of this important injury. The literature on this injury has been reviewed and recommendations for the immediate and early post-operative investigation and management have been brought up to date in line with current thinking.

Spontaneous recurrent haemarthrosis following unicompartmental knee arthroplasty and its successful treatment by coil embolisation

A case of spontaneous recurrent haemarthrosis of the knee presenting 3 months after the unicondylar knee replacement is described. Femoral arteriography demonstrated hypertrophy of the saphenous branch of descending genicular artery with a prominent vascular blush in the region of posteromedial aspect of the popliteal fossa thought to represent a hypertrophic vascular mass of synovium. Therapeutic embolisation of the saphenous branch of descending genicular artery was performed using three fibred platinum coils with satisfactory clinical results. Since the embolisation, the haemarthrosis has not recurred. To our knowledge, this therapeutic procedure used to treat recurrent haemarthrosis following unicondylar knee arthroplasty has not been previously described in the literature.

The 5-hydroxytryptamine type 3 (5-HT3) receptor reveals a novel determinant of single-channel conductance

5-HT3 (5-hydroxytryptamine type 3) receptors are cation-selective ion channels of the Cys-loop transmitter-gated ion channel superfamily. Two 5-HT3 receptor subunits, 5-HT3A and 5-HT3B, have been characterized in detail, although additional putative 5-HT3 subunit genes (HTR3C, HTR3D and HTR3E) have recently been reported. 5-HT3 receptors function as homopentameric assemblies of the 5-HT3 subunit, or heteropentamers of 5-HT3A and 5-HT3B subunits of unknown stoichiometry. The single-channel conductances of human recombinant homomeric and heteromeric 5-HT3 receptors are markedly different, being <1 and approx. 16 pS respectively. Paradoxically, from the results of studies performed on the closely related nicotinic acetylcholine receptor, the channel-lining M2 domain of the 5-HT3A subunit is predicted to enhance cation conduction, whereas that of the 5-HT3B subunit would not. The present study describes a novel determinant of single-channel conductance, outwith the M2 domain, which accounts for this anomaly. Utilizing a panel of chimaeric 5-HT3A and 5-HT3B subunits, a profound determinant of single-channel conductance was traced to a putative amphipathic helix (the ‘HA stretch’) within the large cytoplasmic loop of the receptor. Replacement of three arginine residues (R432, R436 and R440) unique to the HA stretch of the 5-HT3A subunit with the aligned residues (Q395, D399 and A403) of the 5-HT3B subunit increased the single-channel conductance 28-fold. Significantly, from ultrastructural studies of the Torpedo nicotinic acetylcholine receptor, the key residues may be components of narrow openings within the inner vestibule of the channel, located in the cytoplasm, which contribute to the permeation pathway. Our findings indicate an important and hitherto unappreciated function for the HA stretch in the Cys-loop family of transmitter-gated ion channels.

The 'zero charge' partitioning behaviour of noble gases during mantle melting

Noble-gas geochemistry is an important tool for understanding planetary processes from accretion to mantle dynamics and atmospheric formation. Central to much of the modelling of such processes is the crystal-melt partitioning of noble gases during mantle melting, magma ascent and near-surface degassing. Geochemists have traditionally considered the 'inert' noble gases to be extremely incompatible elements, with almost 100 per cent extraction efficiency from the solid phase during melting processes. Previously published experimental data on partitioning between crystalline silicates and melts has, however, suggested that noble gases approach compatible behaviour, and a significant proportion should therefore remain in the mantle during melt extraction. Here we present experimental data to show that noble gases are more incompatible than previously demonstrated, but not necessarily to the extent assumed or required by geochemical models. Independent atomistic computer simulations indicate that noble gases can be considered as species of 'zero charge' incorporated at crystal lattice sites. Together with the lattice strain model, this provides a theoretical framework with which to model noble-gas geochemistry as a function of residual mantle mineralogy.

Free hand-to-toe transfer: a method to minimise donor-site morbidity in free joint transfers

Reconstruction of a congenital hand anomaly in a child using single free vascularised transfer of the proximal interphalangeal joint of a second toe with the simultaneous microvascular reconstruction of the donor toe using the stiff joint and its dorsal skin paddle from the hand is described. This is not the first reported case of a toe-finger switch, but it is the first in a free joint transfer, for which it is especially indicated.

A possible tektite strewn field in the Argentinian Pampa

Impact glass associated with 11 elongate depressions in the Pampean Plain of Argentina, north of the city of Rio Cuarto, was suggested to be proximal ejecta related to a highly oblique impact event. We have identified about 400 additional elongate features in the area that indicate an aeolian, rather than an impact, origin. We have also dated fragments of glass found at the Rio Cuarto depressions; the age is similar to that of glass recovered 800 kilometers to the southeast. This material may be tektite glass from an impact event around 0.48 million years ago, representing a new tektite strewn field.

Allopregnanolone and pentobarbital infused into the nucleus accumbens substitute for the discriminative stimulus effects of ethanol

BACKGROUND

The discriminative stimulus effects of ethanol are mediated in part by the gamma-aminobutyric acid type A (GABA(A)) receptor system. We have previously shown that microinjections of the competitive GABA(A) agonist muscimol in the nucleus accumbens and amygdala fully substitute for the discriminative stimulus effects of systemic ethanol. However, it is not known whether allosteric binding sites on GABA(A) receptors located within specific limbic brain regions contribute to the discriminative stimulus effects of ethanol.

METHODS

Male Long-Evans rats were trained to discriminate between intraperitoneal injections of ethanol (1 g/kg) and saline under a fixed-ratio 10 schedule of sucrose (10% w/v) reinforcement. Injector guide cannulae, aimed at both the nucleus accumbens core and the hippocampus area CA1, were then implanted to allow site-specific infusion of GABA(A)-positive modulators.

RESULTS

Infusion of the neurosteroid 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone, or 3alpha-5alpha-P) in the nucleus accumbens resulted in dose-dependent full substitution for intraperitoneal ethanol (50% effective dose = 0.38 ng/microl per side). Likewise, injection of the barbiturate pentobarbital into the nucleus accumbens also substituted dose-dependently for ethanol (50% effective dose = 1.55 microg/microl per side). However, infusions of either 3alpha-5alpha-P or pentobarbital in the hippocampus failed to substitute for ethanol and produced inverted U-shaped dose-response curves.

CONCLUSIONS

These results demonstrate that allosteric positive modulation of GABA(A) receptors in the nucleus accumbens produces full substitution for the stimulus effects of ethanol. This suggests that GABA(A) receptors in the nucleus accumbens may play a more influential role in the discriminative stimulus effects of ethanol than those in the hippocampus.

Alcohol actions on GABA(A) receptors: from protein structure to mouse behavior

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were R. Adron Harris and Susumu Ueno. The presentations were (1) Protein kinase Cepsilon-regulated sensitivity of gamma-aminobutyric acid type A (GABAA) receptors to allosteric agonists, by Robert O. Messing, A. M. Sanchez-Perez, C. W. Hodge, T. McMahon, D. Wang, K. K. Mehmert, S. P. Kelley, A. Haywood, and M. F. Olive; (2) Genetic and functional analysis of a GABAA receptor gamma2 subunit variant: A candidate for quantitative trait loci involved in alcohol sensitivity and withdrawal, by Kari J. Buck and Heather M. Hood; (3) Tryptophan-scanning mutagenesis in GABAA receptor subunits: Channel gating and alcohol actions, by Susumu Ueno; and (4) Can a single binding site account for actions of alcohols on GABAA and glycine receptors? by R. Adron Harris, Yuri Blednov, Geoffrey Findlay, and Maria Paola Mascia.

The discriminative stimulus properties of self-administered ethanol are mediated by GABA(A) and NMDA receptors in rats

RATIONALE

The neurobiological systems that mediate the discriminative stimulus effects of self-administered drugs are largely unknown. The present study examined the discriminative stimulus effects of self-administered ethanol.

METHODS

Rats were trained to discriminate ethanol (1 g/kg, IP) from saline on a two-lever drug discrimination task with sucrose (10% w/v) reinforcement. Test sessions were conducted with ethanol (0 or 10% v/v) added to the sucrose reinforcement to determine if self-administered ethanol would interact with the discriminative stimulus effects of investigator-administered ethanol, or with the ethanol-like discriminative stimulus effects of the GABAA-positive modulator pentobarbital or the non-competitive NMDA antagonist MK-801.

RESULTS

During a saline test session, ethanol (10% v/v) was added to the sucrose reinforcement. Responding by all animals began accurately on the saline-appropriate lever and then switched to the ethanol-appropriate lever after rats self-administered a mean dose of 1.2 +/- 0.14 g/kg ethanol. During cumulative self-administration trials, responding initially occurred on the saline lever and then switched to the ethanol-appropriate lever after ethanol (0.68 +/- 0.13 g/kg) was self-administered. Investigator-administered MK-801 (0.01-1.0 mg/kg, cumulative IP) and pentobarbital (0.3-10.0 mg/kg, cumulative IP) dose-dependently substituted for ethanol. When ethanol (10% v/v) was added to the sucrose reinforcer, MK-801 and pentobarbital dose-response curves were shifted significantly to the left.

CONCLUSIONS

Self-administered ethanol substituted for and potentiated the stimulus effects of investigator-administered ethanol, suggesting that the discriminative stimulus effects of self-administered ethanol are similar to those produced by investigator-administered ethanol. Self-administered ethanol enhanced the ethanol-like discriminative stimulus effects of MK-801 and pentobarbital, which suggests that the discriminative stimulus effects of self-administered ethanol are mediated by NMDA and GABAA receptors.

Long term modulation of the HPA axis by the hippocampus. Behavioral, biochemical and immunological endpoints in rats exposed to chronic mild stress

Mature rats were given lesions of the hippocampus (HIPPO), subiculum (SUBIC) or fimbria-fornix (FIFO) and then received the mild chronic stressors of food deprivation and isolation housing for ten months prior to testing. Group differences in circadian activity were investigated along with locomotion elicited by amphetamine (AMP 1.0-2.0 mg/kg i.p.) alone, and following the corticosterone (CORT) synthesis inhibitor, metyrapone (MET 10.0-25.0 mg/kg i.p.). Basal levels of plasma CORT, (ng/ml), plasma glucose (GLUC, mmol/l), thymic and splenic wet weights were subsequently determined along with complete blood counts (CBC). In comparison to age matched, unoperated controls, selective SUBIC lesions altered the circadian periodicity of locomotion, while rats with FIFO lesions were spontaneously hyperactive. Both HIPPO and FIFO animals showed significantly higher levels of amphetamine-induced locomotion. In all groups metyrapone significantly enhanced locomotion elicited by amphetamine, probably due to a pharmacokinetic interaction between these drugs. In comparison to controls, animals in the HIPPO group showed significant reductions in plasma glucose levels, decreased thymic wet weights and reductions in lymphocyte numbers, indicating lesion-related immuno-suppression. These findings highlight a functional difference among the effects of these specific hippocampal lesions on neural regulation of the HPA axis, under conditions of chronic mild stress, suggesting that the modulatory influence of the hippocampus on the stress axis is dependent on the neuroanatomical location and total extent of cell loss within this structure. They further suggest that the heightened response to amphetamine occurs independently of any lesion-induced changes in modulation of the HPA axis.

Rapid kimberlite ascent and the significance of Ar-Ar ages in xenolith phlogopites

Kimberlite eruptions bring exotic rock fragments and minerals, including diamonds, from deep within the mantle up to the surface. Such fragments are rapidly absorbed into the kimberlite magma so their appearance at the surface implies rapid transport from depth. High spatial resolution Ar-Ar age data on phlogopite grains in xenoliths from Malaita in the Solomon Islands, southwest Pacific, and Elovy Island in the Kola Peninsula, Russia, indicate transport times of hours to days depending upon the magma temperature. In addition, the data show that the phlogopite grains preserve Ar-Ar ages recorded at high temperature in the mantle, 700 degrees C above the conventional closure temperature.

Supersensitivity to allosteric GABA(A) receptor modulators and alcohol in mice lacking PKCepsilon

Several of the actions of ethanol are mediated by gamma-aminobutyrate type A (GABA(A)) receptors. Here we demonstrated that mutant mice lacking protein kinase C epsilon (PKCepsilon) were more sensitive than wild-type littermates to the acute behavioral effects of ethanol and other drugs that allosterically activate GABA(A) receptors. GABA(A) receptors in membranes isolated from the frontal cortex of PKCepsilon null mice were also supersensitive to allosteric activation by ethanol and flunitrazepam. In addition, these mutant mice showed markedly reduced ethanol self-administration. These findings indicate that inhibition of PKCepsilon increases sensitivity of GABA(A) receptors to ethanol and allosteric modulators. Pharmacological agents that inhibit PKCepsilon may be useful for treatment of alcoholism and may provide a non-sedating alternative for enhancing GABA(A) receptor function to treat other disorders such as anxiety and epilepsy.

Effects of hippocampal damage on reward threshold and response rate during self-stimulation of the ventral tegmental area in the rat

The main purpose of this study was to explore the role of the hippocampus in motivated behavior. Rats with bilateral excitotoxic lesions of the hippocampus and controls were trained to lever press for electrical stimulation of the ventral tegmental area. Rate intensity functions were generated from an ascending and descending series of current intensities. Lesion-induced changes in sensitivity to reward were distinguished from enhancements in motor output by calculating reward thresholds and maximal response rates from the rate-intensity functions. Rats with hippocampal damage showed lower reward thresholds and higher maximal response rates than controls. These results provide further evidence of hippocampal modulation of the nucleus accumbens, suggesting that lesions of this structure enhance sensitivity to reward and increase motor output.

Adrenal hormone modulation of type 1 and type 2 cytokine production by spleen cells: dexamethasone and dehydroepiandrosterone suppress interleukin-2, interleukin-4, and interferon-gamma production in vitro

Our previous work has documented that physical or psychological stress can alter interleukin (IL)-2, IL-4, and interferon (IFN)-gamma production by spleen or lymph node cells in vitro. To determine if adrenal hormones might be mediating these stress-induced changes in type 1 and type 2 cytokines and immune effector functions, we cultured spleen cells in vitro with either the synthetic glucocorticoid dexamethasone (DEX) or the putative restorative hormone dehydroepiandrosterone (DHEA). Spleen cells were obtained from either young (5-6 weeks old) or mature (7-8 months old) BALB/c mice that were either unimmunized or immunized with the T-cell-dependent antigen keyhole limpet hemocyanin (KLH). We determined that DEX suppressed production of all three cytokines examined. DHEA was not associated with any enhancement of cytokine production. These data challenge the hypothesis that glucocorticoids can differentially regulate Th1-like versus Th2-like cytokine production. Further, they suggest that in stress paradigms in which differential regulation of cytokine production and effector function has been observed, other neuroendocrine factors in addition to glucocorticoids must be relevant.

Norepinephrine in mouse spleen shows minor strain differences and no diurnal variation

Strain differences have been invoked to explain differing results when studying neural-immune interactions in laboratory animals. We investigated the splenic norepinephrine (NE) content and concentration in three strains of male mice (BALB/C, C57BL/6, and DBA/2), as well as possible diurnal variability in this innervation. Diurnal plasma corticosterone levels served as a positive control. Mice were housed on a 12 h on/12 h off light/dark cycle for 3 weeks, then sacrificed at one of six times during the 24 h cycle. Spleen NE total content and concentrations were determined using high performance liquid chromatography with electrochemical detection. We found small but significant differences between strains in total resting spleen NE content (BALB/C > C57BL/6 > DBA/2) and in resting NE concentration (C57BL/6 > BALB/C > DBA/2). This may reflect differences in spleen weight (BALB/C > DBA/2 > C57BL/6). The expected diurnal pattern of plasma corticosterone was seen in all strains, but no diurnal differences were found in NE content or concentration.

Timing of Hot Spot--Related Volcanism and the Breakup of Madagascar and India

Widespread basalts and rhyolites were erupted in Madagascar during the Late Cretaceous. These are considered to be related to the Marion hot spot and the breakup of Madagascar and Greater India. Seventeen argon-40/argon-39 age determinations reveal that volcanic rocks and dikes from the 1500-kilometer-long rifted eastern margin of Madagascar were emplaced rapidly (mean age = 87.6 +/- 0.6 million years ago) and that the entire duration of Cretaceous volcanism on the island was no more than 6 million years. The evidence suggests that the thick lava pile at Volcan de l'Androy in the south of the island marks the focal point of the Marion hot spot at approximately 88 million years ago and that this mantle plume was instrumental in causing continental breakup.

Urocanic acid may not be the photoreceptor for UV-induced suppression of contact hypersensitivity

We have tested the hypothesis that urocanic acid is the photoreceptor molecule for ultraviolet radiation-induced systemic suppression of contact hypersensitivity in the mouse. Almost complete removal of urocanic acid by tape-stripping of exposed skin was not associated with abrogation of immune suppression. This finding makes it unlikely that urocanic acid is the chromophore.

Carcinogenesis by nonmutagenic chemicals: early response of rat liver cells induced by methapyrilene

Although methapyrilene (MP) produces hepatocellular carcinomas in rats, it does not elicit many of the cellular responses induced by other hepatocarcinogens. We have investigated the early changes induced in rat liver epithelial cell cultures by MP using morphological, cytochemical, and cytofluorometric techniques. Within 2 h of MP treatment, inclusion bodies which were stainable with lipid stains were observed in the cytoplasm. Ultrastructurally, they resembled lamellar bodies with alternating light and dark lamellae. These bodies were transient in nature, since they disappeared within 24 h of removal of MP. They were, however, retained in the cytoplasm as long as MP was present in the medium. Lamellar bodies appear to be induced in the presence of histamine H1 receptor-blocking agents, since methaphenilene and diphenhydramine produced this reaction, but cimetidine, an H2 antagonist, did not. Morphologically, mitochondria of control cells were long and rod-like, whereas they were short or bizarrely shaped in the MP-treated cells. Moreover, a quantitative increase was observed in the mitochondrial content of the treated cells, when intact liver cells vitally stained with Rhodamine 123 were analyzed with a fluorescence-activated cell sorter. A significant increase in binucleated cells was observed when liver cells were exposed for 10 to 12 days with MP. Collectively, these results suggest that MP might perturb the cytoskeletal elements leading to an alteration in the nuclear and mitochondrial makeup of rat liver cells.

Sunlight suppressing rejection of 280- to 320-nm UV-radiation-induced skin tumors in mice

Repeated exposure of female C3H/HeNCR- mice to sunlight prevented the normal immunologic rejection of a UV-induced tumor. This systemic immunologic alteration was transferred to syngeneic lethally X-irradiated animals with lymphoid cells from mice exposed to sunlight. The lymphoid cells also were able to suppress the capacity of lymphoid cells from normal animals to reject a UV-induced tumor. The 295- to 320-nm wave band appeared to be responsible for this immunosuppressive effect of sunlight because suppression was prevented by filtration of the radiation through Mylar and by application of a sunscreen containing para-aminobenzoic acid. These observations may have importance in understanding the pathogenesis of sunlight-induced skin cancer in humans.

Repeated establishment of diploid epithelial cell cultures from normal and partially hepatectomized rats

A number of liver epithelial cell cultures were established from 10 to 12-d-old sucklings, 6 to 8-wk-old young adults, or from 2 to 18-month-old partially hepatectomized rats. Improvements in the methods for cell isolation and culture yielded replicating cells from every experiment and they were maintained for different periods with regular passages. The proliferative potential in vitro of adult rat liver cells could be increased if the rats were subjected to partial hepatectomy before cell isolation. In the early passages, the majority of the cells were found to have a true diploid karyotype as studied by the Giemsa-banding technique. Under the culture conditions described, a very high percentage of cells remained in the diploid range for, in most cases, at least 4 months and in some cases for up to 6 months. Afterward, the karyotype was unstable, but no "crisis" period was seen before the cells became aneuploid. Until this time, the growth characteristics of the cells also followed a normal pattern showing density dependent inhibition of division and a lack of markers associated with malignancy. The cultured liver cells exhibited a number of liver specific properties when they were maintained as a confluent monolayer. The early passages of diploid epithelial cell cultures derived from normal and regenerating rat liver are good models for studies of the regulation of cell division and the changes that are related to carcinogenesis.

Inability of methapyrilene to induce sister chromatid exchanges in vitro and in vivo

The induction of sister chromatid exchanges (SCE) by the hepatocarcinogen methapyrilene hydrochloride was investigated using appropriate in vitro and in vivo mammalian cell systems. Methapyrilene, even at the maximum tolerated dose, did not induce SCE in Chinese hamster ovary cells (CHO) or when CHO cells or hamster lung fibroblasts, V-79, were cocultivated with early cultures of rat liver epithelial cells, which are known to metabolize different classes of chemical carcinogens to active forms. Moreover, a hybrid clone of cells (formed by fusion of CHO cells with rat liver epithelial cells), which is highly sensitive to SCE formation by a number of xenobiotics, failed to produce SCE after treatment with methapyrilene. Experiments in vivo with bone marrow cells and in vitro with CHO cells cocultivated with primary hepatocytes from rats also confirmed the inability of methapyrilene to induce SCE in the indicator cells. Since aflatoxin B1 induced SCE in the in vitro and in vivo models, it may be concluded that methapyrilene does not induce SCE at a concentration which is not cytotoxic to the indicator cells in the different systems described. Autoradiographic studies in cultured rat liver cells with tritiated methapyrilene showed that the label was localized in the cytoplasm but not in the interphase nuclei or in the metaphase chromosomes, indicating a lack of interaction of methapyrilene with the nuclear macromolecules of the putative target cells for methapyrilene.