Patrick B. Kyle

Elevated level of metabotropic glutamate receptor 2/3 in the prefrontal cortex in major depression.

Clinical, postmortem and preclinical research strongly implicates dysregulation of glutamatergic neurotransmission in major depressive disorder (MDD). Recently, metabotropic glutamate receptors (mGluRs) have been proposed as attractive targets for the discovery of novel therapeutic approaches against depression. The aim of this study was to examine mGluR2/3 protein levels in the prefrontal cortex (PFC) from depressed subjects. In addition, to test whether antidepressants influence mGluR2/3 expression we also studied levels of mGluR2/3 in fluoxetine-treated monkeys. Postmortem human prefrontal samples containing Brodmanns area 10 (BA10) were obtained from 11 depressed and 11 psychiatrically healthy controls. Male rhesus monkeys were treated chronically with fluoxetine (dose escalated to 3mg/kg, p.o.; n=7) or placebo (n=6) for 39 weeks. The mGluR2/3 immunoreactivity was investigated using Western blot method. There was a robust (+67%) increase in the expression of the mGlu2/3 protein in the PFC of depressed subjects relative to healthy controls. The expression of mGlu2/3 was unchanged in the PFC of monkeys treated with fluoxetine. Our findings provide the first evidence that mGluR2/3 is elevated in the PFC in MDD. This observation is consistent with reports showing that mGluR2/3 antagonists exhibit antidepressant-like activity in animal models and demonstrates that these receptors are promising targets for the discovery of novel antidepressants.

Allopregnanolone Reinstates Tyrosine Hydroxylase Immunoreactive Neurons and Motor Performance in an MPTP-Lesioned Mouse Model of Parkinson's Disease

Restorative/protective therapies to restore dopamine neurons in the substantia nigra pars compacta (SNpc) are greatly needed to effectively change the debilitating course of Parkinsons disease. In this study, we tested the therapeutic potential of a neurogenic neurosteroid, allopregnanolone, in the restoration of the components of the nigrostriatal pathway in MPTP-lesioned mice by measuring striatal dopamine levels, total and tyrosine hydroxylase immunoreactive neuron numbers and BrdU-positive cells in the SNpc. An acute treatment (once/week for two weeks) with allopregnanolone restored the number of tyrosine hydroxylase-positive and total cell numbers in the SNpc of MPTP-lesioned mice, even though this did not increase striatal dopamine. It was also noted that MPTP treated mice to which allopregnanolone was administered had an increase in BrdU-positive cells in the SNpc. The effects of allopregnanolone in MPTP-lesioned mice were more apparent in mice that underwent behavioral tests. Interestingly, mice treated with allopregnanolone after MPTP lesion were able to perform at levels similar to that of non-lesioned control mice in a rotarod test. These data demonstrate that allopregnanolone promotes the restoration of tyrosine hydroxylase immunoreactive neurons and total cells in the nigrostriatal tract, improves the motor performance in MPTP-treated mice, and may serve as a therapeutic strategy for Parkinsons disease.

Oligodendrocyte morphometry and expression of myelin – Related mRNA in ventral prefrontal white matter in major depressive disorder

White matter disturbance in the ventral prefrontal cortex (vPFC) in major depressive disorder (MDD) has been noted with diffusion tensor imaging (DTI). However, the cellular and molecular pathology of prefrontal white matter in MDD and potential influence of antidepressant medications is not fully understood. Oligodendrocyte morphometry and myelin-related mRNA and protein expression was examined in the white matter of the vPFC in MDD. Sections of deep and gyral white matter from the vPFC were collected from 20 subjects with MDD and 16 control subjects. Density and size of CNPase-immunoreactive (-IR) oligodendrocytes were estimated using 3-dimensional cell counting. While neither density nor soma size of oligodendrocytes was significantly affected in deep white matter, soma size was significantly decreased in the gyral white matter in MDD. In rhesus monkeys treated chronically with fluoxetine there was no significant effect on oligodendrocyte morphometry. Using quantitative RT-PCR to measure oligodendrocyte-related mRNA for CNPase, PLP1, MBP, MOG, MOBP, Olig1 and Olig2, in MDD there was a significantly reduced expression of PLP1 mRNA (which positively correlated with smaller sizes) and increased expression of mRNA for CNPase, OLIG1 and MOG. The expression of CNPase protein was significantly decreased in MDD. Altered expression of four myelin genes and CNPase protein suggests a mechanism for the degeneration of cortical axons and dysfunctional maturation of oligodendrocytes in MDD. The change in oligodendrocyte morphology in gyral white matter may parallel altered axonal integrity as revealed by DTI.

Severe Illness Associated with Reported Use of Synthetic Cannabinoids - Mississippi, April 2015.

On April 2, 2015, four patients were evaluated at the University of Mississippi Medical Center (UMMC) in Jackson, Mississippi, for agitated delirium after using synthetic cannabinoids. Over the next 3 days, 24 additional persons went to UMMC with illnesses suspected to be related to synthetic cannabinoid use; one patient died. UMMC notified the Mississippi State Department of Health, which issued a statewide alert via the Health Alert Network on April 5, requesting that health care providers report suspected cases of synthetic cannabinoid intoxication to the Mississippi Poison Control Center (MPCC). A suspected case was defined as the occurrence of at least two of the following symptoms: sweating, severe agitation, or psychosis in a person with known or suspected synthetic cannabinoid use. A second statewide alert was issued on April 13, instructing all Mississippi emergency departments to submit line lists of suspected patients to MPCC each day. By April 21, 16 days after the first alert was issued, MPCC had received reports of approximately 400 cases, including eight deaths possibly linked to synthetic cannabinoid use; in contrast, during April 2012–March 2015, the median number of telephone calls to MPCC regarding synthetic cannabinoid use was one per month (range = 0–11). The Mississippi State Department of Health, with the assistance of CDC, initiated an investigation to better characterize the outbreak, identify risk factors associated with severe illness, and prevent additional illnesses and deaths.

Cardiac toxicity of some echinocandin antifungals

Background: Unexplained cardiovascular decompensation has been observed during central venous administration of some echinocandins. Objective: The purpose of this study was to assess cardiac toxicity associated with the echinocandins. Methods: Isolated rat hearts (Langendorff model) were perfused with anidulafungin (ANID), caspofungin (CASP), or micafungin (MICA) at exposures of 1, 4, and 10 times therapeutic concentrations. Changes in left ventricular contractility with experimental exposure were compared to control, and histologic and transmission electron microscopy (TEM) examinations of tissue were performed. Results: Mean concentrations of ANID (10 – 80 µg/ml) and CASP (6 – 48 µg/ml) were associated with significant decreases in contractility (-77.1 ± 9.4% and -40.6 ± 15.6%, respectively; p < 0.05). MICA was associated with an increase in contractility (13.6 ± 2.8%, p = NS). On TEM, samples exposed to ANID and CASP had enlarged mitochondria and disintegrating myofibrils. Samples exposed to MICA showed some enlarged mitochondria. Conclusion: Mean concentrations of ANID and CASP were associated with statistically significant decreases in left ventricular contractility at concentrations that may be achievable in humans after peripheral administration, while MICA caused no change. TEM studies suggest this may be a result of mitochondrial damage. Caution may be warranted with central administration of these agents to patients with preexisting cardiac dysfunction.

Characterization of the development of renal injury in Type-1 diabetic Dahl salt-sensitive rats

The present study compared the progression of renal injury in Sprague-Dawley (SD) and Dahl salt-sensitive (SS) treated with streptozotocin (STZ). The rats received an injection of STZ (50 mg/kg ip) and an insulin pellet (2 U/day sc) to maintain the blood glucose levels between 400 and 600 mg/dl. Twelve weeks later, arterial pressure (143 ± 6 vs. 107 ± 8 mmHg) and proteinuria (557 ± 85 vs. 81 ± 6 mg/day) were significantly elevated in STZ-SS rats compared with the values observed in STZ-SD rats, respectively. The kidneys from STZ-SS rats exhibited thickening of glomerular basement membrane, mesangial expansion, severe glomerulosclerosis, renal interstitial fibrosis, and occasional glomerular nodule formation. In additional studies, treatment with a therapeutic dose of insulin (4 U/day sc) attenuated the development of proteinuria (212 ± 32 mg/day) and renal injury independent of changes in arterial pressure in STZ-SS rats. Since STZ-SS rats developed severe renal injury, we characterized the time course of changes in renal hemodynamics during the progression of renal injury. Nine weeks after diabetes onset, there was a 42% increase in glomerular filtration rate in STZ-SS rats vs. time-control SS rats with reduced renal blood flow. These results indicate that SS rats treated with STZ develop hyperfiltration and progressive proteinuria and display renal histological lesions characteristic of those seen in patients with diabetic nephropathy. Overall, this model may be useful to study signaling pathways and mechanisms that play a role in the progression of diabetes-induced renal disease and the development of new therapies to slow the progression of diabetic nephropathy.

Suspected pediatric ingestions: effectiveness of immunoassay screens vs. gas chromatography/mass spectroscopy in the detection of drugs and chemicals.

Abstract Rapid and accurate analytical testing can be of great value when determining treatment for pediatric patients suspected of ingesting an unknown chemical. Though often overlooked, gas chromatography/mass spectroscopy (GC/MS) can be a valuable resource in emergency toxicology testing. In a recent 24‐month period (July 1999–June 2001), the Analytical Toxicology Laboratory at the University of Mississippi Medical Center, Jackson, MS, compared the results of GC/MS analysis to results obtained by immunoassay testing. The laboratory tested 139 urine samples referred for STAT toxicology testing from the hospitals Pediatric Emergency Department. All samples were tested in parallel using an immunoassay technique (EMIT®) and GC/MS. With analysis by immunoassay, 17.3% of the samples were positive for a drug of abuse. The number of positive drug classes ranged from 0 to 2 per sample (mean 0.17 ± 0.43) using immunoassay. With analysis by GC/MS, drugs were detected in 88.5% of the samples. The number of drugs detected ranged from 0 to 11 per sample (mean 2.2 ± 1.8) with GC/MS. A total of 64 different pharmaceuticals were identified by GC/MS. This study shows that analysis by GC/MS offers the clinician a more comprehensive view into the exposure of the pediatric patient presenting with an unknown chemical ingestion.

Hypertension, inflammation and T lymphocytes are increased in a rat model of HELLP syndrome

Objective: An animal model of hemolysis, elevated liver enzymes, low platelet count (HELLP) was used to determine if T lymphocytes accompany hypertension and increased inflammatory cytokines. Methods: sFlt-1 (4.7 µg/kg/day) and sEndoglin (7 µg/kg/day) were infused into normal pregnant rats (HELLP rats) for 8 days. Results: HELLP was associated with increased mean arterial pressure (p = 0.0001), hemolysis (p = 0.044), elevated liver enzymes (p = 0.027), and reduced platelets (p = 0.035). HELLP rats had increased plasma levels of TNFα (p = 0.039), IL-6 (p = 0.038) and IL-17 (p = 0.04). CD4+ and CD8+ T lymphocytes were increased. Conclusion: These data support the hypothesis that T cells are associated with hypertension and inflammation.

Genetic Susceptibility and Loss of Nr4a1 Enhances Macrophage-Mediated Renal Injury in CKD

Nuclear hormone receptors of the NR4A subgroup have been implicated in cancer, atherosclerosis, and metabolic disease. However, little is known about the role of these receptors in kidney health or disease. Nr4a1-deficient rats (Nr4a1(-/-)) developed on a genetic background susceptible to kidney injury (fawn-hooded hypertensive rat [FHH]) were evaluated for BP, proteinuria, renal function, and metabolic parameters from 4 to 24 weeks-of-age. By week 24, Nr4a1(-/-) rats exhibited significantly higher proteinuria (approximately 4-fold) and decreased GFR compared with FHH controls. The severity of tubular atrophy, tubular casts, and interstitial fibrosis increased significantly in Nr4a1(-/-) rats and was accompanied by a large increase in immune cell infiltration, predominantly macrophages and to a lesser extent T cells and B cells. Global transcriptome and network analyses at weeks 8, 16, and 24 identified several proinflammatory genes and pathways differentially regulated between strains. Bone marrow crosstransplantation studies demonstrated that kidney injury in Nr4a1(-/-) rats was almost completely rescued by bone marrow transplanted from FHH controls. In vitro, macrophages isolated from Nr4a1(-/-) rats demonstrated increased immune activation compared with FHH-derived macrophages. In summary, the loss of Nr4a1 in immune cells appears to cause the increased kidney injury and reduced renal function observed in the Nr4a1(-/-) model.

Hypertension in an Animal Model of HELLP Syndrome is Associated With Activation of Endothelin 1

Women with hypertensive forms of pregnancy such as hemolysis–elevated liver enzymes–low platelet syndrome have increased circulating endothelin 1; however, the relationship between hypertension and endothelin 1 has not been studied. Using an animal model, we sought to determine whether there was an increased activation/dysfunction of endothelin 1, the effect of endothelin 1 receptor-A blockade on hypertension and other manifestations of hemolysis, elevated liver enzymes, and low platelets syndrome. On gestational day 12, timed-pregnant rats were infused with soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEndoglin; 4.7 and 7 µg/kg) via mini-osmotic pumps for 8 days. A subset of rats were treated with receptor-A antagonist (ABT-627, 5mg/kg) for 8 days. Rats with hemolysis-elevated liver enzymes-low platelet syndrome had significantly increased hypertension (P = .0001), circulating endothelin 1 (P = .03), and a significant 3.3- and 7.2-fold increase in preproendothelin messenger RNA (mRNA) expression in the placenta and liver (P = .01 and .04). Urinary protein:creatinine ratio was significantly increased in these animals (P = .0007), and circulating factors from these rats stimulated a significant increase in endothelial cell secretion of endothelin 1 (P = .001) in an in vitro assay. Blockade of the endothelin 1 receptor A significantly decreased hypertension (P = .001), circulating endothelin 1, and interleukin 17 (P = .004 and .003), placental preproendothelin mRNA expression (P = .016), and urinary protein:creatinine ratio (P = .007) in rats with hemolysis–elevated liver enzymes–low platelet syndrome. Blockade of the endothelin 1 receptor A significantly decreased hemolysis (P = .009), liver enzymes (P = .011), and significantly increased platelet levels (P = .03) and decreased circulating CD4+ and CD8+ T lymphocytes (P = .0004 and .0001) in rats infused with sFlt-1 and sEndoglin. These data support the hypothesis that endothelin 1 activation has a critical role in pathophysiology of as hemolysis–elevated liver enzymes–low platelet syndrome.