Clinical application of pulsed Doppler tissue imaging for assessing abnormal left ventricular relaxation.

Conventional assessment of left ventricular (LV) relaxation by calculating the time constant of LV pressure decay during the isovolumic diastole requires an invasive approach. Conversely, noninvasive parameters obtained by measuring isovolumic relaxation time and transmitral flow velocity often give inaccurate information. Using LV pressure curve, pulsed Doppler echocardiography, and pulsed Doppler tissue imaging in 38 patients with heart disease and 12 control subjects, we calculated the time constant and recorded transmitral flow velocity and motion velocities at the endocardial portions of the ventricular septum and LV posterior wall. Compared with the controls, patients exhibited a prolonged time constant, a decreased peak early diastolic velocity of the LV posterior wall, and a prolonged time interval from the second heart sound to the peak of the early diastolic wave. The time constant correlated well with the isovolumic relaxation time and various parameters calculated from the transmitral flow velocity, except in patients with elevated LV end-diastolic pressure. In all subjects, the time constant correlated negatively with the peak early diastolic velocity of the posterior wall and positively with the time from the second heart sound to the peak of the early diastolic wave. Thus, early diastolic parameters derived from the motion velocity of the LV posterior wall by pulsed Doppler tissue imaging were closely related to the time constant. This technique may allow noninvasive evaluation of abnormal LV relaxation in patients with various heart diseases.

History of vitamin D treatment of renal osteodystrophy.

Vitamin D treatment was tried when renal osteodystrophy was first recognized in the early 20th century, using vitamin D2, D3, or dihydrotachysterol. Large doses of vitamin D2 or D3 (150,000-500,000 IU) were prescribed by monitoring serum calcium, phosphate, and alkaline phosphatase. After the discovery of 1,25-dihydroxycholecalciferol, this compound or 1 alpha-hydroxycholecalciferol was applied to the treatment of renal osteodystrophy. In a preclinical study, especially of 1 alpha-hydroxycholecalciferol, nephritogenoside nephritis was the most responsive condition. These active vitamin D preparations are now widely used in patients with chronic renal failure under hemodialysis. Other active vitamin D compounds, such as hexafluoro-1,25-dihydroxycholecalciferol and 22-oxacalcitriol, are also under investigation.

Reduction of homologous blood transfusion in reoperative valve surgery.

From April 1979 to October 1993, 126 adult patients underwent reoperative cardiac valve surgery. Patients were divided into two groups: 53 patients who underwent surgery before January 1990 (group 1) and 73 patients who underwent surgery after January 1990 (group 2). After January 1990, a clinical strategy for reducing homologous blood transfusions was implemented, including the use of predonation of autologous blood in the operating room, reduced heparin doses, an elevated threshold of indication for blood transfusion, and autotransfusion of shed, drained blood after surgery. In group 1, 44 patients (93.0%) received an average of 3785 +/- 1251 ml of homologous blood transfusions. In group 2, only 26 patients (35.6%) needed homologous blood transfusions and had a smaller amount (2985 +/- 1521 ml) on average. Furthermore, only seven patients needed fresh blood transfusion in group 2.

Effects of dietary phosphorus restriction on secondary hyperparathyroidism in hemodialysis patients during intermittent oral high-dose 1,25(OH)2D3 treatment.

Phosphorus (P) retention plays an important role in the pathogenesis of secondary hyperparathyroidism (2nd HPT) in chronic renal failure. In recent years, periodic intravenous or intermittent oral administration of high doses of 1,25(OH)2D3 has been reported to improve severe 2nd HPT in hemodialysis patients. The present study was performed to determine the effects of dietary P restriction on 2nd HPT in hemodialysis patients treated with intermittent oral high-dose 1,25(OH)2D3. A high dose of 1,25(OH)2D3 was administered orally twice a week at the end of hemodialysis in 20 hemodialysis patients with 2nd HPT. Dietary P content was estimated from records of the patients' food intake, made twice during the treatment period. Based on this information, dietitians developed appropriate meal plans and instructed the patients. After 8 weeks of the treatment, serum c-parathyroid hormone (c-PTH) and alkaline phosphatase (ALP) levels decreased significantly, from 18.8 +/- 1.9 ng/ml and 347.1 +/- 30.7 U/liter to 9.4 +/- 1.2 ng/ml and 268.3 +/- 19.6 U/liter, respectively. Serum P levels increased gradually during the first 4 weeks of the treatment. Dietary P intake was reduced significantly, from 908 +/- 49 mg/day to 734 +/- 39 mg/day, after the nutritional instructions. As a result of the dietary P restrictions, serum P levels were significantly decreased in the 8th week as compared with those in the 4th week. Serum Ca levels remained unchanged throughout the observation period. There was a significant relationship between the mean values for serum P levels during the study and the percent suppression of serum c-PTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of intermittent oral 1,25(OH)2D3 therapy on bone Gla protein in dialysis patients.

Serum Bone Gla Protein (BGP) levels were measured by both immunoradiometric assay (IRMA) and radioimmunoassay (RIA) to investigate the effect of intermittent 1,25(OH)2D3 administration to dialysis patients who could not tolerate an increase in an active vitamin D3 dose and/or calcium to control secondary hyperparathyroidism due to hypercalcemia. The administration of active vitamin D3 gradually increased the serum BGP to more than 3 times the original level by the 8th week. At the 12th week after starting the active vitamin D3 therapy, mean BGP was about twice the original level, which was about half the maximum level at the 8th week. The BGP (IRMA)/BGP (RIA) ratio was increased significantly at 4th and 8th weeks compared to the original level. During this period, serum calcium, phosphorous, or intact molecule PTH (I-PTH) levels showed insignificant changes, with a slight reduction in the mid molecule PTH (m-PTH) level, and a significant reduction in ALP. Serum BUN and creatinine levels were not changed significantly. These data suggest that BGP was increased through direct stimulation of osteoblasts by the active vitamin D3, and the increase was not due to deterioration of secondary hyperparathyroidism. The reduction of the increase in the BGP level at the 12th week with insignificant biochemical changes suggest that activation of osteoblasts by vitamin D3 may be transient. In conclusion, intermittent active vitamin D3 increases serum BGP, without deterioration of major biochemical changes even in patients with moderate to severe secondary hyperparathyroidism, although the increase may be transient. These facts suggest that the serum BGP of hemodialysis patients is controlled at least in part by active vitamin D3.(ABSTRACT TRUNCATED AT 250 WORDS)

Response properties of the periodontal mechanosensitive neurons in the thalamus of the cat: a comparison between the slowly adapting and rapidly adapting neurons.

Slowly adapting (SA) and rapidly adapting (RA) types of the periodontal mechanosensitive units (PM units) were recorded in the thalamus and their response properties were examined in the cat. Both types of the PM units were located in the medial area (PM area) of the nucleus ventralis posteromedialis (VPM) of the thalamus. The SA units were located in a rostro-medial part of the PM area, while the RA units were distributed in the caudo-lateral part. An incidence of the SA and RA units was 45.5 and 54.5%, respectively. The single-tooth units were found in 23.5% of the SA units and in 14.9% of the RA units, and they responded chiefly to mechanical stimulation of the contralateral canine tooth. The multi-tooth units of the SA type had smaller receptive fields than those of the RA type, because the majority of the RA units had their receptive fields at the bilateral and/or bimaxillary area. In total, the units having the contralateral receptive fields were also dominant in both adaptation types. The latency of the neuronal discharges to electrical stimulation of the receptive field was fairly shorter in the SA units than in the RA units. These findings suggest that the SA units of the thalamus receive periodontal inputs directly from the trigeminal nuclear complex (Vcomp) of the brain stem, while the RA units receive them polysynaptically from the Vcomp via other pathways.

Response properties of the periodontal mechanosensitive neurons in the trigeminal main sensory nucleus of the cat.

Periodontal mechanosensitive units (PM units) were recorded from the trigeminal main sensory nucleus (Vms) of the cat. The receptive fields of PM units were arranged from mandibular to maxillary divisions dorso-ventrally. The majority of PM units were single tooth units responsive to the canine tooth. They were directionally selective and had sustained responses to pressure applied to the tooth. The optimal stimulus direction of maxillary and mandibular PM units when the canine tooth was stimulated was single and it was oriented predominantly in the caudio-medial or rostrolateral direction. The threshold intensity of canine tooth stimulation was less than 0.05 N in most of the units. These findings indicate that the response properties of PM units in the Vms resemble fairly closely those of the primary afferent nerves arising from the periodontal mechanoreceptors.

Physiological properties of sensory trigeminal neurons projecting to mesencephalic parabrachial area in the cat.

1. One hundred forty-one trigeminomesencephalic neurons in the sensory trigeminal nucleus of cats anesthetized with alpha-chloralose were identified by antidromic stimulation of the mesencephalic parabrachial area (PBA) which includes the nucleus cuneiformis, lateral periaqueductal gray matter, and the region between the inferior colliculus and brachium conjunctivum. 2. Neurons were categorized based on their responses to non-noxious and noxious mechanical and heat stimuli delivered to their peripheral receptive fields (RFs) including skin, mucosa, guard hairs, vibrissae, cornea, and tooth pulps. They were classified into three types: 48 nociceptive-specific (NS) neurons which responded to heavy pressure and/or noxious mechanical stimuli, and/or noxious radiant heat; 19 wide dynamic range (WDR) neurons which had a graded response to light tactile stimuli, noxious pinch, and/or noxious radiant heat; and 36 low-threshold mechanoreceptive (LTM) neurons which responded maximally to innocuous tactile stimuli. In subnucleus caudalis (Vc), NS and WDR neurons were the majority (75%) among the three types, while in the rostral subnuclei they were about one-half (54%) of the population. 3. The RFs were distributed over the orofacial and head region but mainly in the facial region. Twelve neurons (33% of the LTM neurons) responded to deflection of vibrissae and only 1 NS neuron out of 52 NS and WDR neurons tested responded to electrical stimulation of a tooth pulp. 4. A contralateral projection was dominant (57%), 30% projected ipsilaterally and 13% projected bilaterally.(ABSTRACT TRUNCATED AT 250 WORDS)