Hypomagnesemia and mitral valve prolapse in Cavalier King Charles spaniels

There is a high incidence of mitral valve prolapse (MVP), an abnormal displacement of one or both mitral valve leaflets during systole, in Cavalier King Charles Spaniels (CKCS). In humans, MVP is known to be associated with a low magnesium status. In this study, the plasma magnesium concentration was measured in 30 CKCS without heart failure. It was also investigated whether MVP-severity and degree of regurgitation correlated with plasma magnesium and a number of parameters of the renin-angiotensin system, and whether 4 weeks magnesium supplementation affected plasma magnesium or the high renin/low aldosterone profile associated with MVP. A high prevalence of hypomagnesemia was observed: plasma concentrations < 0.70 mmol/l were found in 15 dogs (50%) before and in 12 dogs (40%) after 4 weeks magnesium supplementation. The mean plasma level was 0.69 +/- 0.07 mmol/l before and 0.71 +/- 0.07 mmol/l after magnesium (P = 0.22). Plasma magnesium concentrations did not correlate with MVP-severity and degree of regurgitation. Plasma aldosterone levels correlated negatively with MVP-severity and positively with the degree of regurgitation, and serum angiotensin-converting enzyme activities correlated negatively with the degree of regurgitation. Magnesium supplementation had no effects on renin and aldosterone nor on the ratio between the two. In conclusion, many CKCS without heart failure have hypomagnesemia whether they are fed supplementary magnesium or not--a finding which may be associated with the high prevalence of MVP in this breed. Further studies, however, are needed to clarify the role of a low magnesium status in canine MVP.     

Reduced microvascular thrombosis and improved outcome in acute murine stroke by inhibiting GP IIb/IIIa receptor-mediated platelet aggregation

Treatment options in acute stroke are limited by a dearth of safe and effective regimens for recanalization of an occluded cerebrovascular tributary, as well as by the fact that patients present only after the occlusive event is established. We hypothesized that even if the site of major arterial occlusion is recanalized after stroke, microvascular thrombosis continues to occur at distal sites, reducing postischemic flow and contributing to ongoing neuronal death. To test this hypothesis, and to show that microvascular thrombosis occurs as an ongoing, dynamic process after the onset of stroke, we tested the effects of a potent antiplatelet agent given both before and after the onset of middle cerebral arterial (MCA) occlusion in a murine model of stroke. After 45 min of MCA occlusion and 23 h of reperfusion, fibrin accumulates in the ipsilateral cerebral hemisphere, based upon immunoblotting, and localizes to microvascular lumena, based upon immunostaining. In concordance with these data, there is a nearly threefold increase in the ipsilateral accumulation of 111In-labeled platelets in mice subjected to stroke compared with mice not subjected to stroke. When a novel inhibitor of the glycoprotein IIb/IIIa receptor (SDZ GPI 562) was administered immediately before MCA occlusion, platelet accumulation was reduced 48%, and fibrin accumulation was reduced by 47% by immunoblot densitometry. GPI 562 exhibited a dose-dependent reduction of cerebral infarct volumes measured by triphenyltetrazolium chloride staining, as well as improvement in postischemic cerebral blood flow, measured by laser doppler. GPI 562 caused a dose-dependent increase in tail vein bleeding time, but intracerebral hemorrhage (ICH) was not significantly increased at therapeutic doses; however, there was an increase in ICH at the highest doses tested. When given immediately after withdrawal of the MCA occluding suture, GPI 562 was shown to reduce cerebral infarct volumes by 70%. These data support the hypothesis that in ischemic regions of brain, microvascular thrombi continue to accumulate even after recanalization of the MCA, contributing to postischemic hypoperfusion and ongoing neuronal damage.     

Corrected formula for the calculation of the electrical heart axis

Right brain damage results in a variety of cognitive and behavioural dysfunctions. Mutism however, has been described only with left or bihemispheric lesions involving the parietal lobe. We report an elderly man who had left faciobrachial monoparesis and concomitant mutism. His auditory-verbal comprehension was intact. MRI revealed a right parietal infarct involving the cortical and subcortical regions. Recovery from mutism during the course of treatment was abrupt and complete with no residual dysarthria. A possibility of diaschisis or impaired modulation of left hemispheric function due to right cerebral infarct, presenting as conversion reaction, is proposed for this rare association.     

Stratum radiatum giant cells: a type of principal cell in the rat hippocampus

Neurons of a distinct type in CA1 area stratum radiatum of the rat hippocampus have been found to express a direct cellular form of long-term potentiation (LTP, Maccaferri & McBain, 1996, J. Neurosci. 16, 5334), but their functional identity, i.e. whether interneuron or principal cell, remained unknown. Whole cell recording from hippocampal slices in vitro was combined with light and electron microscopy to answer this question. LTP was robustly induced by a pairing protocol and physiological properties were measured in radiatum giant cells (RGCs) using biocytin containing pipettes. Reconstruction of the cells' dendritic and axonal arbor revealed morphological properties similar to CA1 pyramidal cells with some characteristic differences. They typically had two large diameter apical dendrites, or when only one dendrite arose, it soon bifurcated. Apical dendrites formed a dendritic tuft in stratum lacunosum-moleculare and the dendrites, but not the somata, were densely covered with conventional spines. The axon arose from the basal pole of the soma, descended to stratum oriens and emitted several axon terminals bearing collaterals that travelled horizontally, remaining in stratum oriens. The main, myelinated axon trunks turned towards the fimbria. In the electron microscope axon terminals were found to form asymmetrical synapses on postsynaptic dendritic shafts and dendritic spines in stratum oriens. The dendrites received asymmetrical synapses, mostly on their spines. The axon initial segments also received several synapses, a feature never observed on interneurons. All the above characteristics support the conclusion that RGCs are excitatory principal neurons.     

Accuracy of a new wrist cuff oscillometric blood pressure device: comparisons with intraarterial and mercury manometer measurements

Accurate measurement of arterial blood pressure is of great importance for the diagnosis and treatment of hypertension. Because of the chronic nature of antihypertensive drug therapy, the involvement of the patient in blood pressure control is desirable. Such an involvement, however, is only feasible if simple, user-friendly, and precise blood pressure measurement devices are available. In this study we tested a new wrist cuff oscillometric blood pressure measurement device in 100 consecutive patients undergoing cardiac catheterization. Blood pressures were simultaneously taken intraarterially (axillary artery) and with a mercury manometer and stethoscope or noninvasive measurement device (OMRON R3). Intraarterial measurements were directly compared with two measurements taken in random order with either an arm cuff mercury manometer or the wrist cuff device. Systolic and diastolic blood pressure as assessed with the mercury manometer was higher, especially when compared with the intraarterial and the wrist cuff values, which were comparable. Correlations of blood pressure values with intraarterial measurement were 0.86 systolic and 0.75 diastolic (P < .01) for the wrist cuff and 0.84 systolic (P < .01) and 0.59 diastolic (P < .05) for the mercury manometer measurements. Reproducibility of both measurements was good for the wrist cuff device ([systolic/diastolic]: r = 0.94/0.92; P < .01) and the mercury manometer (r = 0.97/0.88; P < .01). Both methods overestimated high diastolic values, whereas only the wrist cuff underestimated high systolic values. Thus, the new oscillometric wrist cuff blood pressure measurement device measures arterial blood pressure with great accuracy and reproducibility. As compared with intraarterial values, the wrist cuff device overestimated high diastolic and underestimated high systolic blood pressure values. Blood pressure values as measured by the mercury manometer were higher than intraarterial values and those of the wrist cuff. Both noninvasive devices overestimated high diastolic values.     

Basic fibroblast growth factor in experimental and clinical bacterial meningitis

Basic fibroblast growth factor (bFGF), a neurotrophic factor in the CNS, is expressed at high levels in response to seizures or strokes. We examined the expression of bFGF during experimental bacterial meningitis and the levels of bFGF in the cerebrospinal fluid (CSF) of children with bacterial meningitis. For the experimental study, a mouse model of meningitis was established by intracranial injection of Streptococcus pneumoniae. Twenty-four hours after induced meningitis, the brains were sectioned and stained immunohistochemically for bFGF. Neutrophils and macrophages infiltrating the leptomeninges and the ventricles exhibited strong bFGF immunoreactivity. The neurons in the areas adjacent to the inflamed ventricles also showed enhanced bFGF expression. For the clinical study, we used an enzyme immunoassay to measure bFGF in CSF in 18 children with bacterial meningitis, 12 with aseptic meningitis, and 18 controls. The CSF levels of bFGF were twice as high in children with bacterial meningitis (medians 6.75-7.21 pg/mL) compared with those who had aseptic meningitis (2.9 pg/mL) or in control subjects (2.65 pg/mL, p < 0.0001, respectively). In patients with bacterial meningitis who survived, CSF bFGF decreased significantly after 24-50 h of antibiotic therapy (p < 0.0005). Patients who developed major sequelae or died had much higher levels of CSF bFGF than those without (134.9 pg/mL versus 7.38 pg/mL, p < 0.05). These findings of enhanced immunoreactivity of bFGF in experimental bacterial meningitis and an association of CSF levels of bFGF with disease severity in childhood bacterial meningitis suggest a biologic role for this neurotrophic factor in the pathophysiology of bacterial meningitis.     

Aesthetic restoration with full-coverage porcelain veneers and a Ceromer/fiber-reinforced composite framework: a case report

Due to the recent evolution of dental materials and procedures, the restoration of a particular clinical condition can be accomplished by various alternatives. While the use of integrated treatment modalities permit the restoration team to utilize the benefits of each material simultaneously, it requires the development of a comprehensive preoperative treatment plan to address the specific concerns of each region or material utilized. This article describes the use of a multidisciplinary approach to restore proper occlusion, function, and aesthetics in a patient with worn dentition.     

Microstructural investigation of a rapidly solidified 12Cr-Mo-V steel

Rapidly solidified martensitic stainless steel (11.59Cr-0.98Mo-0.28V (in wt pct) ribbons have been produced by the melt-spinning process. The microstructure of the ribbons showed three distinct zones: a columnar, a cellular, and a cellular-dendritic zone. The height of the columnar grain zone is independent of the process parameters such as the wheel material or the wheel velocity. Due to a high level of undercooling and a high growth velocity of the solid/liquid interface, the rapid solidification process is found to suppress the formation of δ-ferrite and enhance the formation of austenite. The austenite is transformed into martensite upon cooling. In comparison with conventional solidification, a reduction in the initial austenite grain size has been found to result in a very fine lath martensite (M) structure. Investigations of the texture within the ribbons along the growth direction show a weak fiber texture. Transmission electron microscopy (TEM) has revealed a [111]_M1 ‖ [001]_M2 and (011)_M1 ‖ (110)_M2 orientation relationship between two neighboring martensite laths. The observed orientation relationship is a result of a superposition of both the Kurdjumov-Sachs (K-S) and Nishiyama-Wasserman (N-W) orientation relations.     

Endoluminal treatment of vascular occlusive disease

The logical desire to avoid major cutaneous incisions and surgical dissection in the treatment of vascular occlusive disease has, in recent years, led to a surge of new therapeutic options whereby access to the diseased blood vessel is obtained via a distant site and treatment is effected from within the vessel. Such endoluminal treatment modalities include thrombolysis, balloon angioplasty, atherectomy, stenting, and stent grafting. For the purpose of this surgically oriented article, the latter two techniques are discussed.