Altered temporal lobe white matter lipid ion profiles in an experimental model of sporadic Alzheimer's disease

BACKGROUND

White matter is an early and important yet under-evaluated target of Alzheimer's disease (AD). Metabolic impairments due to insulin and insulin-like growth factor resistance contribute to white matter degeneration because corresponding signal transduction pathways maintain oligodendrocyte function and survival.

METHODS

This study utilized a model of sporadic AD in which adult Long Evans rats administered intracerebral streptozotocin (i.c. STZ) developed AD-type neurodegeneration. Temporal lobe white matter lipid ion profiles were characterized by matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS).

RESULTS

Although the lipid ion species expressed in the i.c. STZ and control groups were virtually identical, i.c. STZ mainly altered the abundances of various lipid ions. Correspondingly, the i.c. STZ group was distinguished from control by principal component analysis and data bar plots. i.c. STZ mainly reduced expression of lipid ions with low m/z's (less than 810) as well as the upper range m/z lipids (m/z 964-986), and increased expression of lipid ions with m/z's between 888 and 937. Phospholipids were mainly included among the clusters inhibited by i.c. STZ, while both sulfatides and phospholipids were increased by i.c. STZ. However, Chi-Square analysis demonstrated significant i.c. STZ-induced trend reductions in phospholipids and increases in sulfatides (P<0.00001).

CONCLUSIONS

The i.c. STZ model of sporadic AD is associated with broad and sustained abnormalities in temporal lobe white matter lipids. The findings suggest that the i.c. STZ model could be used for pre-clinical studies to assess therapeutic measures for their ability to restore white matter integrity in AD.

Tobacco Smoke-Induced Brain White Matter Myelin Dysfunction: Potential Co-Factor Role of Smoking in Neurodegeneration

BACKGROUND

Meta-analysis studies showed that smokers have increased risk for developing Alzheimer's disease (AD) compared with non-smokers, and neuroimaging studies revealed that smoking damages white matter structural integrity.

OBJECTIVE

The present study characterizes the effects of side-stream (second hand) cigarette smoke (CS) exposures on the expression of genes that regulate oligodendrocyte myelin-synthesis, maturation, and maintenance and neuroglial functions.

METHODS

Adult male A/J mice were exposed to air (8 weeks; A8), CS (4 or 8 weeks; CS4, CS8), or CS8 followed by 2 weeks recovery (CS8 + R). The frontal lobes were used for histology and qRT-PCR analysis.

RESULTS

Luxol fast blue, Hematoxylin and Eosin stained histological sections revealed CS-associated reductions in myelin staining intensity and narrowing of the corpus callosum. CS exposures broadly decreased mRNA levels of immature and mature oligodendrocyte myelin-associated, neuroglial, and oligodendrocyte-related transcription factors. These effects were more prominent in the CS8 compared with CS4 group, suggesting that molecular abnormalities linked to white matter atrophy and myelin loss worsen with duration of CS exposure. Recovery normalized or upregulated less than 25% of the suppressed genes; in most cases, inhibition of gene expression was either sustained or exacerbated.

CONCLUSION

CS exposures broadly inhibit expression of genes needed for myelin synthesis and maintenance. These adverse effects often were not reversed by short-term CS withdrawal. The results support the hypothesis that smoking contributes to white matter degeneration, and therefore could be a key risk factor for a number of neurodegenerative diseases, including AD.

Zinner's syndrome: an up-to-date review of the literature based on a clinical case

The authors made an up-to-date review of the literature concerning the management of Zinner's syndrome and evaluated a young patient with Zinner's syndrome who had presented with urinary and ejaculatory complaints. Physical examination and transrectal ultra-sonography showed a 7.0 cm right seminal vesicle cyst. Magnetic resonance imaging (MRI) confirmed the diagnosis of Zinner's syndrome. Oligoasthenoteratozoospermia was present at the two seminal analyses. Symptomatic improvement was achieved with conservative measures. Actually, the patient is still on a follow-up programme. The diagnosis is usually established at the age of increased sexual activity. Patients may be asymptomatic or present pain, irritative urinary or ejaculatory symptoms and infertility. MRI has proved to be the best imaging examination. Treatment should be adapted to symptoms, surveillance being the best option in the absence of clinical manifestations. Surgical approach may be adequate when conservative measures prove ineffective. Zinner's syndrome should be suspected if a male young patient presents with unilateral renal agenesis and pelvic complaints and has a supraprostatic mass on digital rectal examination. The initial approach should be medical, but invasive procedures may be the only way to solve the patient's complaints. Nowadays, laparoscopic and robotic techniques must replace the open surgical approach.

["Reverse reperfusion" in myocardial scintigraphy perfusion with technetium-99m isonitrile. Incidence and clinical implications]

PURPOSE

Evaluation of the incidence and clinical implications of perfusion defects that appear worse in the rest than the stress myocardial perfusion imaging with technetium-99m isonitrile (MIBI), similar to the reverse redistribution described with thallium-201.

METHODS

The studies of 730 consecutive patients with known or suspected coronary artery disease who underwent either diagnostic or prognostic (after myocardial infarction) technetium-99mMIBI planar scans were reviewed. Usual planar images were subjective and semi-quantitative analyzed. Patients were divided in two groups according to the indication of the test. The incidence of the reverse reperfusion pattern, the correlative findings with the angiographic coronary anatomy, when available, and its clinical implications were assessed.

RESULTS

Three in the 540 (0.55%) patients of the diagnostic group and 6 out of the 190 (3.15%) patients of the myocardial infarction group have shown the "reverse reperfusion" pattern, with an overall incidence of 1.23%. Perfusion defects were anterior in 2 and inferior in 1 patient of the diagnostic group, compared to 4 anterior and 2 inferior within the prognostic population patients. One patient of the diagnostic group and 4 of the prognostic group showed ST-T changes on the exercise ECG. All of them achieved at least 85% of the maximum predicted heart rate during the stress test. The only patient with the "reverse reperfusion" pattern in the diagnostic group had no coronary disease at angiography, while the 6 patients in the post myocardial infarction group have shown either an occluded (2 cases) or recanalized infarct related artery (2 cases) and remote coronary disease (2 cases). Three of them underwent successful coronary angioplasty based on clinical and laboratory evidences of ischemia.

CONCLUSION

The "reverse reperfusion" with technetium 99-m MIBI is an uncommon finding and may be associated with jeopardized myocardium after infarction, although its predictive value for recanalized infarct related artery seems to be very low. It seems to provide no added value towards coronary artery disease diagnosis. Additional experience is required in selected subgroups of patients in order to clarify the clinical value of the "reverse reperfusion" pattern with the technetium-99m MIBI.