Zfhx3-mediated genetic ablation of the SCN abolishes light entrainable circadian activity while sparing food anticipatory activity.

Circadian rhythms persist in almost all organisms and are crucial for maintaining appropriate timing in physiology and behaviour. Here, we describe a mouse mutant where the central mammalian pacemaker, the suprachiasmatic nucleus (SCN), has been genetically ablated by conditional deletion of the transcription factor Zfhx3 in the developing hypothalamus. Mutants were arrhythmic over the light-dark cycle and in constant darkness. Moreover, rhythms of metabolic parameters were ablated in vivo although molecular oscillations in the liver maintained some rhythmicity. Despite disruptions to SCN cell identity and circuitry, mutants could still anticipate food availability, yet other zeitgebers - including social cues from cage-mates - were ineffective in restoring rhythmicity although activity levels in mutants were altered. This work highlights a critical role for Zfhx3 in the development of a functional SCN, while its genetic ablation further defines the contribution of SCN circuitry in orchestrating physiological and behavioral responses to environmental signals.

Plastic physicians: The surgical salamanders of the COVID-19 pandemic.

At the time of writing, coronavirus disease-2019 (COVID-19) has affected 6.42 million people globally and over 380,000 deaths, with the United Kingdom now having the highest death rate in Europe. The plastic surgery department at Leeds Teaching Hospitals put necessary steps in place to maintain an excellent urgent elective and acute service whilst also managing COVID-positive medical patients in the ward. We describe the structures and pathways implemented together with complex decision-making, which has allowed us to respond early and effectively. We hope these lessons will prove a useful tool as we look to open conversations around the recovery of normal activity.

The effects of microchipping C57BL/6N mice on standard phenotyping tests.

The C57BL/6N inbred lines of mice are widely used in genetic research. They are particularly favoured in large scale studies such as the International Mouse Phenotyping Consortium (IMPC), where C57BL/6N mice are genetically altered to generate a collection of null alleles (currently more than 8500 null alleles have been generated). In this project, mice carrying null alleles are subjected to a pipeline of broad-based phenotyping tests to produce wide ranging phenotyping data on each model. We have previously described the development of a Home Cage Analysis system that automatically tracks the activity of group housed mice from a microchip inserted in the groin. This platform allows assessment of multiple biologically relevant phenotypes over long periods of time without experimenter interference, and therefore is particularly suited for high through-put studies. To investigate the impact of microchips on other tests carried out in the IMPC pipeline, we inserted microchips in 12 male and 12 female C57BL/6Ntac mice at seven weeks of age. Starting at nine weeks of age these mice underwent standard phenotyping tests, concurrently with 20 unchipped C57BL/6Ntac mice (10 females, 10 males). Tissues from a subset of the microchipped mice (six males and six females), chosen at random, were also sent for histopathological examination at the end of the phenotyping pipeline. No significant impact of insertion of microchip was observed in any of the phenotyping tests apart from bone mineral density measurement at DEXA due to the nature of the microchip. We therefore recommend that the microchip be inserted during the DEXA procedure, after the measurement is taken but before the mouse has recovered from the anaesthetic. This would avoid multiple anaesthetic exposures and prevent the potential variability in DEXA analysis output.

Sevoflurane and propofol depolarize mitochondria in rat and human cerebrocortical synaptosomes by different mechanisms.

BACKGROUND AND OBJECTIVES: The mitochondrial membrane potential drives the main functions of the mitochondria. Sevoflurane depolarizes neural mitochondria. There is still, however, limited information concerning the effect of anaesthetics on neural mitochondria in humans. The effect of sevoflurane and propofol on the intracellular Ca(2+) concentration [Ca(2+)](i) and the mitochondrial membrane potential (DeltaPsi(m)) was therefore compared in rat and human synaptosomes, and the changes were related to interventions in the electron transport chain. METHODS: Synaptosomes from rat and human cerebral cortex were loaded with the fluorescent probes fura-2 ([Ca(2+)](i)) and JC-1 (DeltaPsi(m)) before exposure to sevoflurane 1 and 2 minimum alveolar concentration (MAC), and propofol 30 and 100 microM. The effect on the electron transport chain was investigated by blocking complex V. RESULTS: Sevoflurane and propofol decreased DeltaPsi(m) in rat synaptosomes in a dose-dependent manner, and to the same extent by equipotent doses. Inhibition of complex V enhanced the depolarizing effect of sevoflurane 2 MAC, but not of propofol 100 microM. Neither sevoflurane nor propofol affected [Ca(2+)](i) significantly. Sevoflurane and propofol decreased DeltaPsi(m) in human synaptosomes to the same extent as in the rat experiments. CONCLUSIONS: Sevoflurane and propofol at equipotent doses depolarize the mitochondria in rat and human nerve terminals to the same extent. The depolarizing effect of propofol on Psi(m) was more rapid in onset than that of sevoflurane. Whereas sevoflurane inhibits the respiratory chain sufficiently to cause ATP synthase reversal, the depolarizing effect of propofol seems to be related to inhibition of the respiratory chain from complex I to V.

Morphological determinants of femoral strength in growth hormone-deficient transgenic growth-retarded (Tgr) rats.

UNLABELLED: The extent to which childhood GHD affects adult fracture risk is unclear. We measured femoral strength in adult transgenic growth-retarded rats as a model of GHD. Long-term, moderate GHD was accompanied by endocrine and morphometric changes consistent with a significant reduction in femoral strength. INTRODUCTION: Childhood growth hormone deficiency (GHD) is associated with osteopenia, but little is known about its effects on subsequent adult bone strength and fracture risk. MATERIALS AND METHODS: We have therefore measured femoral strength (failure load measured by three-point bending) in a new model of moderate GHD, the transgenic growth-retarded (Tgr) rat at 15, 22-23, and 52 weeks of age, and have quantified potential morphological and endocrine determinants of bone strength. RESULTS: Skeletal growth retardation in Tgr rats was accompanied by a sustained reduction in the anterior-posterior diameter of the femoral cortex, whereas mid-diaphyseal cortical wall thicknesses were largely unaltered. Total femoral strength was significantly impaired in Tgr rats (p < 0.01), and this impairment was more pronounced in males than females. Compromised bone strength in Tgr rats could not be accounted for by the reduction in mechanical load (body weight) and was not caused by impairment of the material properties of the calcified tissue (ultimate tensile stress), despite marked reductions in femoral mineral density (areal bone mineral density; p < 0.001). Microcomputerized tomographical analysis revealed significant modification of the architecture of trabecular bone in Tgr rats, with reductions in the number and thickness of trabeculae (p < 0.05) and in the degree of anisotropy (p < 0.01). The marked reduction in plasma insulin-like growth factor-1 in Tgr rats was accompanied by the development of high circulating leptin levels (p < 0.01). CONCLUSION: These results show that the changes in endocrinology and bone morphology associated with long-term moderate GHD in Tgr rats are accompanied by changes consistent with a significant reduction in the threshold for femoral fracture.

Effect of antisense knock-down of alpha(2a)- and alpha(2c)-adrenoceptors on the antinociceptive action of clonidine on trigeminal nociception in the rat.

Although activation of alpha(2)-adrenoceptors is known to play an important role in mediating antinociception, the contribution of various alpha(2)-adrenoceptor subtypes in modulating trigeminal nociception remains unknown since subtype specific agonists and antagonists are not available. The present study investigated the functional role of alpha(2)-adrenoceptor subtypes in modulating the N-methyl-D-aspartate-induced nociceptive behavior in the medullary dorsal horn by using antisense oligodeoxynucleotides to selectively knock-down the receptor subtypes. Microinjection of N-methyl-D-aspartate (2 nmol in 10 microl) through a cannula implanted dorsal to the medullary dorsal horn produced a total of 164.9+/-8.8 scratches in the facial region (n=14), and the scratching behavior lasted for 77.8+/-5.2s (n=14). Microinjection of clonidine, an alpha(2)-agonist (7 microg in 5 microl), 15 min prior to administration of N-methyl-D-aspartate, produced a reduction of 71.6% (n=12) in the number of scratches and a reduction of 57.5% (n=12) in the duration. The inhibitory effect of clonidine was blocked by idazoxan (n=4) and yohimbine (n=4), alpha(2) antagonists. In rats pretreated with the antisense probe to the alpha(2A) adrenoceptor, clonidine only produced a reduction of 7.3% in the number of scratches (n=12) and a reduction of 9% in the duration (n=12). The antinociceptive effect of clonidine recovered completely 4 days after termination of the alpha(2A) antisense oligodeoxynucleotide treatment. In contrast to the alpha(2A) antisense-treated animals, clonidine reduced the number of scratches and the duration by 85.5% (n=9) and 82.1% (n=9), respectively, in rats pretreated with the sense probe to the alpha(2A) adrenoceptor. The effect of clonidine was not altered in rats pretreated with the antisense or the sense probes to the alpha(2C) adrenoceptor. In the alpha(2C) antisense pretreated rats, clonidine reduced the number of scratches and the duration by 60.8% (n=11) and 44.5 % (n=11), respectively. In the sense-pretreated rats, clonidine produced a reduction of 69.1% in the number of scratches (n=9) and a reduction of 55.1% in the duration (n=9). In order to assess the effectiveness of the antisense treatment, the receptor expression was examined by immunohistochemistry. Antisense treatment reduced alpha(2A) and alpha(2C) receptor immunoreactivity in the medullary dorsal horn compared to the sense and the vehicle-treated animals. Quantitative image analysis revealed a significant decrease in pixel intensity following the antisense treatment. These results indicate that activation of alpha(2A) adrenoceptor plays an important role in mediating the antinociceptive effect of clonidine in the medullary dorsal horn in the rat.

Uveal lymphoid neoplasia: a clinical-pathologic correlation and review of the early form.

We report three cases of uveal lymphoid neoplasia that were diagnosed early in their course. One case exhibited a posterior form, presenting with progressive hyperopia from a serous-macular detachment and choroidal involvement along with retrobulbar involvement. This patient was treated with proton beam irradiation. Two cases displayed an anterior form, with fixed fleshy epibulbar masses resembling salmon patches, and choroidal involvement. The histologic findings from biopsy of these anterior masses are presented. One of these patients was treated with complete excision of the mass and double freeze-thaw cryotherapy of the scleral bed, and the other patient was treated with conventional photon beam irradiation. The clinical features of uveal lymphoid neoplasia in its early form are discussed. Evaluation and treatment strategies for these early forms of uveal lymphoid neoplasia are reviewed.

The conjugacy of human saccadic eye movements.

Binocular measurements of instantaneous velocity vectors in normal human subjects during saccades showed: (1) considerable trial to trial variation in peak velocity, saccade duration, and saccade curvature despite saccade accuracy; (2) variations in one eye were mirrored by similar variations in the other eye, with a high positive correlation. The high correlation between the peak velocities suggest that saccades in the two eyes are driven by a common saccade generator. Assuming that a local feedback loop guides saccades, the high correlation between saccade durations and between saccade curvatures suggests that both eyes are guided by common feedback. If so, monocular adaptation must occur downstream from the saccade generator.

The role of acute decompression and restoration of spinal alignment in the prevention of post-traumatic syringomyelia: case report and review of recent literature.

STUDY DESIGN: Case report. INTRODUCTION: Acute post-traumatic syringomyelia formation after spinal cord injury has been considered a rare complication. At this writing, most recent reports have surfaced in neurosurgical journals. As an entity, post-traumatic syringomyelia has not been widely appreciated. It has been confused with conditions such as Hansen's disease or ulnar nerve compression at the cubital tunnel. One study also demonstrated that the occurrence of syrinx is significantly correlated with spinal stenosis after treatment, and that an inadequate reduction of the spine may lead to the formation of syrinx. This reported case describes a patient in whom post-traumatic syringomyelia began to develop 3 weeks after injury, which improved neurologically after adequate decompression. SUMMARY OF BACKGROUND DATA: A 30-year-old man sustained a 20-foot fall at work. He presented with a complete spinal cord injury below T4 secondary to a T4 fracture dislocation. The patient underwent open reduction and internal fixation of T1-T8. After 3 weeks, the patient was noted to have ascending weakness in his bilateral upper extremities and some clawing of both hands. METHODS: A computed tomography myelogram demonstrated inability of contrast to pass through the T4-T5 region from a lumbar puncture. An incomplete reduction was noted. The canal showed significant stenosis. A magnetic resonance image of the patient's C-spine showed increased signal in the substance of the cord extending into the C1-C2 area. The patient returned to the operating room for T3-T5 decompressive laminectomy and posterolateral decompression including the pedicles, disc, and posterior aspect of the body. Intraoperative ultrasound monitoring showed a good flow of cerebrospinal fluid past the injured segment. RESULTS: On postoperative day 1, the clawing posture of the patient's hands was significantly diminished, and the patient noted an immediate improvement in his hand and arm strength. Over the next few days, the patient's strength in the bilateral upper extremities increased to motor Grade 4/5 on manual testing. A magnetic resonance image 4 weeks after decompression showed significant improvement in the cord diameter and signal. CONCLUSIONS: Post-traumatic syringomyelia has not been reported at so early a stage after injury. This disorder is an important clinical entity that must be recognized to prevent potentially fatal or devastating complications. As evidenced by the reported patient and the literature, if this disorder is discovered and treated early, permanent deficit can be avoided. The prevention of post-traumatic syringomyelia requires anatomic realignment and stabilization of the spine without stenosis, even in the case of complete injuries, to maintain the proper dynamics of cerebrospinal fluid flow.

Prospective, randomized, double-blind study comparing single-agent antibiotic therapy, ciprofloxacin, to combination antibiotic therapy in open fracture wounds.

OBJECTIVE: The purpose of this study was to compare the efficacy of a single agent, ciprofloxacin, with that of combination antibiotic therapy consisting of cefamandole and gentamicin in all types of open fracture wounds. STUDY DESIGN: A prospective double-blind randomized clinical trial. SETTING: A Level 1 trauma center. PATIENTS: One hundred ninety-five consecutive patients with 203 open fractures were enrolled over a twenty-month period. Twenty-nine fractures from low-velocity gunshot wounds were excluded, and three other patients were excluded because of protocol violations. Our final number of patients were 163, with 171 open fractures. MAIN OUTCOME MEASUREMENT: The infection rates for Type I and Type II open fractures for both antibiotic groups were calculated. The infection rate of Type III open fractures for both antibiotic groups was also calculated. Chi-square analysis with Yates correction was used to assess statistical significance of two treatment groups. RESULTS: The infection rate for Types I and II open fractures in the ciprofloxacin group was 5.8 percent and 6 percent for the cefamandole/gentamicin group (p = 1.000). The infection rate for Type III open fractures for the ciprofloxacin group was 31 percent (8 of 26) versus 7.7 percent (2 of 26) for the cefamandole/gentamicin group (p = 0.079). There were no statistically significant differences in infection rate between the group treated with ciprofloxacin and that treated with cefamandole/gentamicin for Types I and II open fracture wounds. However, there appeared to be a high failure rate for the ciprofloxacin Type III open fracture group, with patients being 5.33 times more likely to become infected than those in the combination therapy group. Although this difference was not statistically significant, possibly because of the small sample size, there was a definite trend toward statistical significance. CONCLUSION: Single-agent antibiotic therapy with ciprofloxacin is effective in treatment of Type I and Type II open fracture wounds. However, on the basis of our results, we cannot recommend ciprofloxacin alone for Type III wounds. Possibly one can use fluoroquinolones in combination therapy, specifically as an alternate to an aminoglycoside.

Stereological estimation of the absolute number of glomeruli in the kidneys of lambs.

An association between the arrest of renal development and intra-uterine growth retardation (IUGR) has been demonstrated in human beings and it has been suggested that the same defect may occur in the kidneys of lambs affected by IUGR. Using design-based stereological methods, the physical disector and Cavalieri's principle, smaller absolute numbers of glomeruli were found in all six IUGR lambs studied with a low birthweight and in two of six control lambs studied with a normal birthweight than in other lambs with a normal birthweight. There was no difference in absolute numbers of glomeruli between twin births and singletons. The absolute numbers of glomeruli in three stillborn lambs were distributed among results obtained from the normal and IUGR lambs in accordance with their individual bodyweights. IUGR had a profound detrimental effect on the renal development of the lambs.

Cryotherapy for treatment of active retinopathy of prematurity: experience in London, Ontario.

Between January 1985 and May 1990, 49 infants (97 eyes) with stage 3 "plus" retinopathy of prematurity (ROP) were treated with cryopexy. The mean gestational age at birth was 29.6 weeks and the mean birth weight 753 g. At the time of treatment the mean chronologic age was 8.7 weeks and the mean weight 1629 g. Noncutting cryopexy was applied to the entire avascular peripheral retina, anterior to the mesenchymal ridge. Confluent treatment was done anteriorly to the posterior border of the pars plana. Favourable results, defined as a normal-appearing fundus (apart from the cryopexy scars) with no retinal folds or traction, were observed in 70% of the eyes an average of 13.8 (range 2 to 60) months after treatment. Our results emphasize the importance of early detection of ROP and diligent monitoring and treatment of affected infants.

Peroxidase labelling immunocytochemistry: a comparison of eleven commercially-available avidin-biotin systems.

Eleven commercially produced avidin-biotin peroxidase labelling systems employed in immunocytochemistry were compared by titrating a monoclonal and a polyclonal antibody onto routinely prepared formalin-fixed paraffin wax sections of tonsil and appendix. The cost per test for each labelling system was also calculated.

The role of ankle arthroscopy on the surgical management of ankle fractures.

Nineteen patients were prospectively randomized for operative treatment of their ankle fracture to be supplemented with or without ankle arthroscopy. All patients had an SER or PER fracture with an intact medial malleolus requiring operative treatment without evidence of intra-articular debris preoperatively. All patients underwent plate fixation of their fibula fracture and had a similar postoperative protocol. Ten patients were randomized to the control group with plate fixation only and nine patients randomized to the plate fixation plus operative arthroscopy. The average follow-up was 21 months. The arthroscopic examination of the study group revealed eight of the nine patients to have articular damage to the dome of the talus. Minimal arthroscopic treatment of these joints was required. All patients healed their fractures. No difference was noted between SF-36 scores or lower extremity scores between the two groups. At short-term follow-up, it does not appear that the arthroscopic procedure will impact upon the patient's eventual outcome in this small group of patients.

Changes in mitochondrial function are pivotal in neurodegenerative and psychiatric disorders: how important is BDNF?

The brain is at the very limit of its energy supply and has evolved specific means of adapting function to energy supply, of which mitochondria form a crucial link. Neurotrophic and inflammatory processes may not only have opposite effects on neuroplasticity, but also involve opposite effects on mitochondrial oxidative phosphorylation and glycolytic processes, respectively, modulated by stress and glucocorticoids, which also have marked effects on mood. Neurodegenerative processes show marked disorders in oxidative metabolism in key brain areas, sometimes decades before symptoms appear (Parkinson's and Alzheimer's diseases). We argue that brain-derived neurotrophic factor couples activity to changes in respiratory efficiency and these effects may be opposed by inflammatory cytokines, a key factor in neurodegenerative processes.