The ventral tegmental area revisited: is there an electrophysiological marker for dopaminergic neurons?

The ventral tegmental area (VTA) and in particular VTA dopamine (DA) neurons are postulated to play a central role in reward, motivation and drug addiction. However, most evidence implicating VTA DA neurons in these functions is based on indirect electrophysiological characterization, rather than cytochemical identification. These physiological criteria were first established in the substantia nigra pars compacta (SNc), but their validity in the VTA is uncertain. In the current study we found that while 88 ± 2% of SNc neurons labelled by the neuronal marker NeuN were co-labelled for the catecholamine enzyme tyrosine hydroxylase (TH), a much smaller percentage (55 ± 2%) of VTA neurons co-expressed TH. In addition, using in vitro whole-cell recordings we found that widely accepted physiological criteria for VTA DA neurons, including the hyperpolarization-activated inwardly rectifying non-specific cation current ( I _h), spike duration, and inhibition by DA D2 receptor agonists, do not reliably predict the DA content of VTA neurons. We could not distinguish DA neurons from other VTA neurons by size, shape, input resistance, I _h size, or spontaneous firing rate. Although the absence of an I _h reliably predicted that a VTA neuron was non-dopaminergic, and I _h(−) neurons differ from I _h(+) neurons in firing rate, interspike interval (ISI) standard deviation, and ISI skew, no physiological property examined here is both sensitive and selective for DA neurons in the VTA. We conclude that reliable physiological criteria for VTA DA neuron identification have yet to be determined, and that the criteria currently being used are unreliable.     

Grandparental genotyping enhances exome variant interpretation

Trio exome sequencing is a powerful tool in the molecular investigation of monogenic disorders and provides an incremental diagnostic yield over proband‐only sequencing, mainly due to the rapid identification of de novo disease‐causing variants. However, heterozygous variants inherited from unaffected parents may be inadvertently dismissed, although multiple explanations are available for such scenarios including mosaicism in the parent, incomplete penetrance, imprinting, or skewed X‐inactivation. We report three probands, in which a pathogenic or likely pathogenic variant was identified upon exome sequencing, yet was inherited from an unaffected parent. Segregation of the variants (in NOTCH1, PHF6, and SOX10) in the grandparent generation revealed that the variant was de novo in each case. Additionally, one proband had skewed X‐inactivation. We discuss the possible genetic mechanism in each case, and urge caution in data interpretation of exome sequencing data. We illustrate the utility of expanding segregation studies to the grandparent generation and demonstrate the impact on exome interpretation strategies, by showing that objective genotype data can overcome subjective parental report of lack of symptoms.     

Thin (less than or equal to 1 mm) melanomas of the extremities are biologically favorable lesions not influenced by regression.

Although a thickness of less than or equal to 0.76 mm has been used to define biologically favorable (thin) melanoma, there is evidence that 1 mm may be a reasonable cutoff to categorize favorable extremity melanomas. This is tempered, however, by the claim that histologic regression in thin melanomas is associated with an increased metastatic rate. We have therefore addressed the following questions: Is 1 mm an appropriate cutoff point to define thin melanoma on the extremities? Does regression in a thin lesion truly signify a poor prognosis? Is the width of excision (narrow vs. wide) related to recurrence rates in these lesions? To address these issues we reviewed 48 patients with extremity melanomas, less than or equal to 1 mm in maximum thickness, treated at this institution during a 20-year period. Pathologic features included histologic type: superficial spreading (90%), nodular (6%), and not classified (4%); thickness: less than 0.76 mm (61%) and 0.76 to 1 mm (39%); and Clark''s level: II (33%), III (63%), and IV (4%). A moderate or marked lymphoid infiltrate occurred in 75%, and histologic tumor regression was found in 50%. The median margin of excision, as stated by the surgeon, was 4 cm. The median margin measured by the pathologist in unfixed specimens was 3.5 cm. Although 13% had atypical melanocytic hyperplasia in the initial excisional biopsy margin, all reexcisions were clear. Of 21 patients having node dissections, none had nodal metastases. There were no recurrences or deaths due to melanoma (median follow-up: 90 months). We conclude that melanomas less than or equal to 1 mm in thickness on the extremities can be defined as biologically highly favorable, "thin" lesions. Foci of regression do not alter their behavior. Their favorable prognosis justifies conservative excision in most cases.     

Anticholinergic and antiglutamatergic agents protect against soman-induced brain damage and cognitive dysfunction.

Soman, a powerful inhibitor of acetylcholinesterase, causes an array of toxic effects in the central nervous system including convulsions, learning and memory impairments, and, ultimately, death. We report on the protection afforded by postexposure antidotal treatments, combined with pyridostigmine (0.1 mg/kg) pretreatment, against these consequences associated with soman poisoning. Scopolamine (0.1 mg/kg) or caramiphen (10 mg/kg) were administered 5 min after soman (1.2 LD50), whereas TAB (i.e., TMB4, atropine, and benactyzine, 7.5, 3, and 1 mg/kg, respectively) was injected in rats concomitant with the development of toxic signs. Atropine (4 mg/kg) was given to the two former groups at the onset of toxic symptoms. Caramiphen and TAB completely abolished electrographic seizure activity while scopolamine treatment exhibited only partial protection. Additionally, no significant alteration in the density of peripheral benzodiazepine receptors was noted following caramiphen or TAB administration, while scopolamine application resulted in a complex outcome: a portion of the animals demonstrated no change in the number of these sites whereas the others exhibited markedly higher densities. Cognitive functions (i.e., learning and memory processes) evaluated using the Morris water maze improved considerably by the three treatments when compared to soman-injected animals; the following rank order was observed: caramiphen > TAB > scopolamine. Additionally, statistically significant correlations (r = 0.72, r = 0.73) were demonstrated between two learning parameters and [3H]Ro5-4864 binding to brain membrane. These results show that drugs with a pharmacological profile consisting of anticholinergic and antiglutamatergic properties such as caramiphen and TAB, have a substantial potential as postexposure therapies against intoxication by organophosphates.     

Kidney Transplantation and COVID-19: Two Case Reports

Immunocompromised populations are at great risk of the current 2020 global emergency of coronavirus disease 2019 (COVID-19), and treatment of kidney transplant recipients with COVID-19 is currently not declared. Hence, the purpose of the study is to set a clear treatment regimen. We report here a therapeutic course of 2 patients who underwent transplant surgery in March 2020 and got infected soon after. Since the transplant, these 2 patients have received triple maintenance immunosuppressive therapy with oral tacrolimus, mycophenolate mofetil (MMF), and prednisone, and they have been regularly followed up at our hospital. The tacrolimus trough level was between 10 and 12 ng/mL. After the diagnosis of COVID-19, MMF was stopped and the tacrolimus dose was reduced so that blood level was between 4 and 6 ng/mL. The first patient was a 30-year-old man who, despite being treated with hydroxychloroquine, favipiravir, oseltamivir, and azithromycin therapy, died because of the presence of other comorbidities. The second case was a 58-year-old man who fully recovered from COVID-19 pneumonia with treatment with methylprednisolone, MMF, azithromycin, favipiravir, hydroxychloroquine, and reduction in immunosuppression dosage. This reflects the importance of using glucocorticoids in the treatment of COVID-19 along with other medications and the decreased mortality rate associated with their use.     

Focal and segmental glomerulosclerosis in murine models: a histological and ultrastructural characterization with immunohistochemistry correlation of glomerular CD44 and WT1 expression

Aim: Focal segmental glomerulosclerosis (FSGS) is a common progressive chronic renal disease. Podocyte injury and loss are the postulated pivotal events that trigger FSGS. In this study, the authors aim to examine the evolution of FSGS in murine models histologically, ultrastructurally and immunohistochemically with special emphasis on podocytes and parietal epithelial cells (PECs). Material and methods: FSGS resembling primary FSGS in humans was initiated in Wistar rats using intravenous Adriamycin injections. Blood and urine analysis were performed at 0, 8, and 12 weeks. Both the control kidneys and the test kidneys were harvested at 8 and 12 weeks, examined histologically and ultrastructurally and the findings correlated with the glomerular expression of immunostains specific for podocytes (WT-1) and for activated PECs (CD44). Results: FSGS developed in both 8 and 12 weeks test groups showing progressive proteinuria, podocytopathy and segmental glomerular scarring. There was a decrease in the glomerular expression of WT-1 with a concurrent increase in the glomerular expression of CD44, indicating podocyte loss with synchronous increase in activated PECs. The evolving FSGS correlated negatively with podocytes and positively with activated PECs. Conclusion: Our study shows that with podocyte injury there is podocyte effacement and loss, proteinuria, glomerular segmental adhesion and scarring, all culminating in FSGS. In addition, there is activation, hyperplasia and hypertrophy of PECs. This demonstrates that both podocyte loss and PEC activation promote FSGS. Our findings are consistent with recent investigations. More studies are required to further understand the role of these cells in the evolution of FSGS and subsequently introduce new targeted treatment modalities.     

Practical compendium for psoriasis management

Psoriasis management is complex and challenging. It should be tailored for each patient. Treatment strategy differs according to patient's age, sex, disease type, disease severity, burden on patient's quality of life, comorbidities, involvement of specific sites, and pregnancy. The choice of the appropriate therapeutic must take into consideration the availability, the price, and the patient's preferences. It is very important that the chosen treatment is not more unpleasant, intolerable, or dangerous than the disease itself. According to the disease type, severity, and effect on patient's quality of life, dermatologist chooses whether to start with topical therapy, phototherapy or systemic therapy, or a combination of two or more of them. Under each category, there are different types of therapies that can be the first line therapeutics, second line, or even contraindicated. In this compendium, we provide dermatologists with different treatment plans considering all the mentioned variables so that a dermatologist can choose the optimum plan for the patient.