Subthalamic nucleus deep brain stimulation does not alter growth factor expression in a rat model of stable dopaminergic deficiency

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been a highly effective treatment option for mid-to-late-stage Parkinson's disease (PD) for decades. Besides direct effects on brain networks, neuroprotective effects of STN-DBS - potentially via alterations of growth factor expression levels - have been proposed as additional mechanisms of action.

OBJECTIVE

In the context of clarifying DBS mechanisms, we analyzed brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) levels in the basal ganglia, motor and parietal cortices, and dentate gyrus in an animal model of stable, severe dopaminergic deficiency.

METHODS

We applied one week of continuous unilateral STN-DBS in a group of stable 6-hydroxydopamine (6-OHDA) hemiparkinsonian rats (6-OHDASTIM) in comparison to a 6-OHDA control group (6-OHDASHAM) as well as healthy controls (CTRLSTIM and CTRLSHAM). BDNF and GDNF levels were determined via ELISAs.

RESULTS

The 6-OHDA lesion did not result in a persistent alteration in either BDNF or GDNF levels in a model of severe dopaminergic deficiency after completion of the dopaminergic degeneration. STN-DBS modestly increased BDNF levels in the entopeduncular nucleus, but even impaired BDNF and GDNF expression in cortical areas.

CONCLUSIONS

STN-DBS does not increase growth factor expression when applied to a model of completed, severe dopaminergic deficiency in contrast to other studies in models of modest and ongoing dopaminergic degeneration. In healthy controls, STN-DBS does not influence BDNF or GDNF expression. We consider these findings relevant for clinical purposes since DBS in PD is usually applied late in the course of the disease.

Enhanced Palmitate-Induced Interleukin-8 Formation in Human Macrophages by Insulin or Prostaglandin E2

Macrophages in pathologically expanded dysfunctional white adipose tissue are exposed to a mix of potential modulators of inflammatory response, including fatty acids released from insulin-resistant adipocytes, increased levels of insulin produced to compensate insulin resistance, and prostaglandin E₂ (PGE₂) released from activated macrophages. The current study addressed the question of how palmitate might interact with insulin or PGE₂ to induce the formation of the chemotactic pro-inflammatory cytokine interleukin-8 (IL-8). Human THP-1 cells were differentiated into macrophages. In these macrophages, palmitate induced IL-8 formation. Insulin enhanced the induction of IL-8 formation by palmitate as well as the palmitate-dependent stimulation of PGE₂ synthesis. PGE₂ in turn elicited IL-8 formation on its own and enhanced the induction of IL-8 release by palmitate, most likely by activating the EP4 receptor. Since IL-8 causes insulin resistance and fosters inflammation, the increase in palmitate-induced IL-8 formation that is caused by hyperinsulinemia and locally produced PGE₂ in chronically inflamed adipose tissue might favor disease progression in a vicious feed-forward cycle.

Laparoscopic pericardial window

The creation of a drainage orifice in the pericardium for the release of an accumulated effusion has been proven to be an effective means to eliminate the physiologic effects of a cardiac tamponade. Numerous surgical approaches have been used to create an opening in the pericardium for this purpose. Thoracic and thoracoscopic approaches have been found to produce a fair amount of morbidity by further compromising an already compromised cardiopulmonary system by necessitating an invasion into the hemithorax and the requirement of a thoracostomy tube. This report identifies a laparoscopic technique for the creation of a pericardial window with low morbidity that has been successfully used in 14 patients who presented to the Department of Surgery of the Rapid City Medical Center with clinical evidence of pericardial effusion and tamponade.

[Functional results of patellectomy]

A follow-up of 41 patients 1-10 years after patellectomy was performed. A discrepancy between subjective satisfaction of the patient and objective functional results could be observed. Best results can be expected after patellectomy due to traumatic comminution of the patella. Patellectomy due to degenerative destruction of the patella results in decreasing pain but exercises only low influence on the functional result. Instability after patellectomy can be explained by loss of the major patellar function (sesamy bone in the patella and quadriceps tendon). The intact patella is of great importance. However, patellectomy of destroyed patellas is considered very helpful. Competent concomitant and after treatment as well as an accurate diagnosis at the right time are prerequisites for good results.