Optogenetic manipulation of neural circuits in awake marmosets

Optogenetics has revolutionized the study of functional neuronal circuitry (Boyden ES, Zhang F, Bamberg E, Nagel G, Deisseroth K. Nat Neurosci 8: 1263-1268, 2005; Deisseroth K. Nat Methods 8: 26-29, 2011). Although these techniques have been most successfully implemented in rodent models, they have the potential to be similarly impactful in studies of nonhuman primate brains. Common marmosets (Callithrix jacchus) have recently emerged as a candidate primate model for gene editing, providing a potentially powerful model for studies of neural circuitry and disease in primates. The application of viral transduction methods in marmosets for identifying and manipulating neuronal circuitry is a crucial step in developing this species for neuroscience research. In the present study we developed a novel, chronic method to successfully induce rapid photostimulation in individual cortical neurons transduced by adeno-associated virus to express channelrhodopsin (ChR2) in awake marmosets. We found that large proportions of neurons could be effectively photoactivated following viral transduction and that this procedure could be repeated for several months. These data suggest that techniques for viral transduction and optical manipulation of neuronal populations are suitable for marmosets and can be combined with existing behavioral preparations in the species to elucidate the functional neural circuitry underlying perceptual and cognitive processes.

Cinacalcet HCl (Sensipar/ Mimpara) is an effective chronic therapy for hemodialysis patients with secondary hyperparathyroidism

AIMS

This 1-year double-blind, placebo-controlled, multicenter study evaluated the long-term safety and efficacy of cinacalcet for the treatment of secondary hyperparathyroidism in patients receiving hemodialysis.

METHOD

Patients were randomly assigned in a 1:1 ratio to cinacalcet or control treatment groups. The initial dose of cinacalcet (or matching placebo) was 30 mg. Doses were titrated every 3 or 4 weeks based on the intact parathyroid hormone (iPTH) response and safety profile. Sequential doses included 30, 60, 90, 120 and 180 mg/d. Phosphate binders and vitamin D sterols were adjusted per protocol as needed to control levels of calcium and phosphorus. Efficacy and safety were compared between treatment groups among patients who completed the study (52 total weeks of treatment). Reasons for withdrawal are presented for patients who did not complete the study.

RESULTS

A total of 210 patients completed 52 weeks of double-blinded treatment with cinacalcet (n = 99) or placebo (n = 111). Over the last 6 months of the study, a greater proportion of patients in the cinacalcet group than the control group achieved an iPTH level < or = 250 pg/ml (61.6 vs. 9.9%, p < 0.001) or a > or = 30% decrease in iPTH from baseline (81.8 vs. 21.6%, p < 0.001). Mean iPTH levels decreased by -47.8% in the cinacalcet group and increased by +12.9% in the control group. Mean percentage changes in other laboratory values in the cinacalcet and control groups included the following: serum calcium -6.5 vs. +0.9% (p < 0.001), serum phosphorus -3.6 vs. -1.1% (p = 0.465), and Ca x P -9.9 vs. -0.3% (p = 0.006). The most commonly reported adverse events related to study drug by the investigators included nausea (13% cinacalcet, 5% control), investigator-reported hypocalcemia (11% cinacalcet, 1% control), vomiting (9% cinacalcet, 2% control), dyspepsia (5% cinacalcet, 4% control), and diarrhea (5% cinacalcet, 2% control).

CONCLUSIONS

Treatment with cinacalcet is a safe and effective therapy for long-term control of secondary hyperparathyroidism. 1-year therapy with cinacalcet was associated with sustained, clinically significant reductions in calcium, Ca x P and iPTH which allowed a greater percentage of patients to achieve NKF-KDOQI target goals for PTH and Ca x P.

An unusual case of port site seeding

We present an unusual case of a port site tumor from a colonic adenocarcinoma following laparoscopic cholecystectomy. A 66-year-old woman with a previous renal transplant underwent elective laparoscopic cholecystectomy for symptomatic cholelithiasis. Three months later, she re-presented with pain localized to the right lateral port wound. Subsequent investigation revealed an adenocarcinoma in the ascending colon with no evidence of local spread or liver metastases. The patient was enrolled in the ALCCAS trial (an Australasian multicenter prospective randomized clinical study comparing laparoscopic and conventional open surgical treatments of colon cancer in adults) and randomized to the laparoscopic arm. At laparoscopy, nodules of tumor were located at the sites of the previous right flank and umbilical trocar sites. The procedure was converted to an open hemicolectomy with excision of port sites. To our knowledge, only one other case of a colon carcinoma metastasizing to a port site following laparoscopic cholecystectomy has been reported. This case illustrates a number of points: (a) This was an advanced tumor at the time of diagnosis and was undoubtedly present at laparoscopic cholecystectomy. (b) This tumor was not manipulated at the time of laparoscopic cholecystectomy. (c) The patient was immunosuppressed at the time of laparoscopic cholecytstectomy. (d) The patient developed clinical recurrence in her laparotomy wound within 3 months of her open procedure. This case supports current arguments that the etiology of port site metastases is likely to be mulifactorial.

Neurosteroids mediate habituation and tonic inhibition in the auditory midbrain

Habituation of the behavioral response to a repetitive stimulus is a well-established observation in perceptual studies and is considered a basic form of nonassociative learning. There is also a long history of physiological studies suggesting that central nervous system habituation is mediated by inhibition. At higher levels of the sensory pathways, such inhibition is mainly contributed by GABAa receptor mechanisms. Concepts of modification of synaptic efficacy that apply to excitatory amino acid synaptic transmission do not have direct parallels with these inhibitory synapses: quantal release of GABA rapidly saturates available receptors at a synapse, placing an upper limit on responsiveness to increased transmitter release. However, pharmacological modulation of GABAa-receptor efficacy with exogenous agents (e.g., benzodiazepines and beta-carbolines) is known to occur through allosteric mechanisms that modulate the effectiveness (positive and negative) of GABA at this receptor. The most potent endogenous modulators are 5alpha-reduced steroids. Production of these steroids was attenuated in adult rats with systemic injection of Finasteride, a competitive substrate for 5alpha-reductase. This treatment was sufficient to block habituation of the evoked midbrain response to repetitive presentation of an acoustic click. This result confirms that simple habituation is due to an increase in active inhibition, the increase being mediated by steroid modulation of the GABAa-receptor. Finasteride treatment also brought about a 23% increase in the evoked response to a click stimulus, suggesting that 5alpha-reduced steroids normally contribute to tonic inhibition in the rat inferior colliculus.

Evaluation of hand function in patients undergoing long term haemodialysis

OBJECTIVE

Haemodialysis is associated with the deposition of beta(2) microglobulin in musculoskeletal structures, leading to the syndrome of dialysis related amyloidosis and impairment of hand function. This study aimed at assessing hand function using the Sollerman test in a cross section of patients undergoing haemodialysis.

METHODS

Recipients of haemodialysis underwent the Sollerman test of hand grip function, which assesses 20 activities of daily living using eight grip types, and the JAMAR grip strength test, visual analogue scales (VAS) for pain (VAS-P) and function (VAS-F), and Health Assessment Questionnaire (HAQ) were determined. Results-Thirty five subjects (26 male), with mean age 53.2 years, participated. The average duration of haemodialysis was 6.2 years (range one month to 25 years). The median Sollerman score was 77, with 19/35 (54%) patients receiving haemodialysis having a score below the lower normal value of 78-80. The log Sollerman score correlated poorly with age (rs=0.16, p=0.35), and significantly with the HAQ score (r(s)=-0.66, p<0.00005), duration of haemodialysis (rs=-0.39, p<0.05), VAS-F (rs=-0.41, p<0.05), VAS-P (rs=-0.34, p<0.05), and JAMAR score (rs=0.57, p<0.05). Sollerman scores were highly correlated between dominant and non-dominant hands (rs=0.69, p<000005).

CONCLUSIONS

Hand dysfunction is a common finding among patients undergoing long term haemodialysis. The Sollerman test accurately reflects patient function as measured by HAQ, VAS-F, and grip strength, but less so pain. Its use for the early detection of dialysis related amyloidosis and in the serial monitoring of the effects of hand treatment programmes is encouraged.

Premature development of erosive osteoarthritis of hands in patients with chronic renal failure

The prevalence of grade III or IV osteoarthritis was determined in 210 patients with chronic renal failure, of whom 94 were receiving chronic haemodialysis and 116 had functioning renal transplants. The prevalence of grade III or IV osteoarthritis was three times greater in patients under 65 than in a control population, and all but two affected patients also had erosion of subchondral bone in at least one affected joint. The excess of osteoarthritis was apparent in both the transplant recipients and those receiving haemodialysis. Over the age of 65 there was no significant difference in prevalence. Metabolic bone disease, including osteopenia, might contribute to the development of erosive osteoarthritis in chronic renal failure.

'Dialysis related arthropathy': a survey of 95 patients receiving chronic haemodialysis with special reference to beta 2 microglobulin related amyloidosis

Ninety five patients receiving chronic haemodialysis (CHD) were surveyed to determine the prevalence of rheumatic disease and, where possible, its aetiology. At least three distinct rheumatic syndromes were identified--a group of patients with a syndrome consisting of large and medium joint synovial swelling, restricted hips and shoulders, tenosynovitis, carpal tunnel syndrome, and bone cysts due to deposition of beta 2 microglobulin related amyloid (AM beta 2m); a second group with erosive azotaemic osteoarthropathy; and a third group with age related degenerative disease of small, large, and axial joints. The data presented suggest that in patients receiving CHD (a) the prevalence of AM beta 2m deposition and the associated syndrome increases with duration of dialysis, but in patients who have been dialysed for more than 10 years the risk of developing AM beta 2m is related to age; (b) AM beta 2m deposition in subchondral cysts, but not synovium, causes joint destruction; also, AM beta 2m may be more prone to deposition in synovium of joints already damaged by other processes; (c) in the absence of synovial iron deposition synovial AM beta 2m is not associated with an inflammatory infiltrate; (d) hyperparathyroidism and perhaps other factors such as synovial iron deposition are probably more important than AM beta 2m as causes of peripheral joint degeneration and destructive spondyloarthropathy in patients receiving CHD.

Is chronic renal failure a risk factor for the development of erosive osteoarthritis?

Erosive osteoarthritis of the hands of unusually early onset and severity was seen in two patients treated for chronic renal failure by long term haemodialysis and renal homograft respectively. The significance of this observation is discussed in the light of previous studies of erosive arthropathy in patients with chronic renal failure. Factors associated with chronic renal failure may predispose to the development of erosive osteoarthritis.

Renal transplantation in Australia and New Zealand, 1963-1982: report from the ANZ Data Registry

In Australia, more than 400 transplants are performed annually, the majority of primary grafts from CADs. The patient survival rate that has increased gradually over the period from 1976 to 1982 may be attributed to decreased steroid use for both rejection and maintenance immunosuppression. Our data suggest that B and DR locus antigens are important histocompatibility antigens, that the effects of additive for both loci, and the influence of histocompatibility at the B locus and DR locus is stronger for the transfused sensitized (responder) patient. Age has more influence on patient survival than on graft survival.