Metformin alters dendrite development and synaptic plasticity in rat cortical neurons

Synaptic plasticity is crucial as it dynamically molds the strength and connectivity of neural circuits, influencing learning, memory, and the development of neurological disorders. Metformin, a widely prescribed anti-diabetic medication, has been shown to readily cross the blood-brain barrier (BBB) and the placenta. However, its prolonged impact on neuronal morphology and functions remains underexplored. In this study, we investigated the influence of metformin on dendrite development and synaptic plasticity in embryonic brains and primary rat cortical neurons. Our findings reveal a negative modulation of dendrite development by metformin, as evidenced by altered dendritic arborization, impaired dendritic spine morphology and disruptions in synaptic plasticity, suggesting a potential link between metformin exposure and aberrations in neuronal connectivity. In addition, we extend our insights to the impact of maternal metformin exposure on embryonic brains, revealing a significant inhibition of dendrite development in E18.5 rat brains. In conclusion, this study adds to the expanding knowledge base on the non-metabolic effects of metformin, emphasizing the significance of assessing its potential influence on both neuronal structure and function. There is an urgent need for further investigations into the enduring impact of prolonged metformin administration on the structural and functional aspects of neurons.

Metformin inhibits nerve growth factor (NGF)-induced sympathetic neuron differentiation through p35/CDK5 inhibition

The authors' previous research has shown the pivotal roles of Cyclin-dependent kinase 5 (CDK5) and its regulatory protein p35 in nerve growth factor (NGF)-induced differentiation of sympathetic neurons in PC12 cells. During the process of differentiation, neurons are susceptible to environmental influences, including the effects of drugs. Metformin is commonly used in the treatment of diabetes and its associated symptoms, particularly in diabetic neuropathy, which is characterized by dysregulation of the sympathetic neurons. However, the impacts of metformin on sympathetic neuronal differentiation remain unknown. In this study, we investigated the impact of metformin on NGF-induced sympathetic neuronal differentiation using rat pheochromocytoma PC12 cells as a model. We examined the regulation of TrkA-p35/CDK5 signaling in NGF-induced PC12 differentiation. Our results demonstrate that metformin reduces NGF-induced PC12 differentiation by inactivating the TrkA receptor, subsequently inhibiting ERK and EGR1. Inhibition of this cascade ultimately leads to the down-regulation of p35/CDK5 in PC12 cells. Furthermore, metformin inhibits the activation of the pre-synaptic protein Synapsin-I, a substrate of CDK5, in PC12 differentiation. Additionally, metformin alters axonal and synaptic bouton formation by inhibiting p35 at both the axons and axon terminals in fully differentiated PC12 cells. In summary, our study elucidates that metformin inhibits sympathetic neuronal differentiation in PC12 cells by disrupting TrkA/ERK/EGR1 and p35/CDK5 signaling. This research contributes to uncovering a novel signaling mechanism in drug response during sympathetic neuronal differentiation, enhancing our understanding of the intricate molecular processes governing this critical aspect of neurodevelopment.

Impact of metformin on neocortical development during pregnancy: Involvement of ERK and p35/CDK5 pathways

Metformin, the most commonly prescribed drug for the treatment of diabetes, is increasingly used during pregnancy to address various disorders such as diabetes, obesity, preeclampsia, and metabolic diseases. However, its impact on neocortex development remains unclear. Here, we investigated the direct effects of metformin on neocortex development, focusing on ERK and p35/CDK5 regulation. Using a pregnant rat model, we found that metformin treatment during pregnancy induces small for gestational age (SGA) and reduces relative cortical thickness in embryos and neonates. Additionally, we discovered that metformin inhibits neural progenitor cell proliferation in the sub-ventricular zone (SVZ)/ventricular zone (VZ) of the developing neocortex, a process possibly mediated by ERK inactivation. Furthermore, metformin induces neuronal apoptosis in the SVZ/VZ area of the developing neocortex. Moreover, metformin retards neuronal migration, cortical lamination, and differentiation, potentially through p35/CDK5 inhibition in the developing neocortex. Remarkably, compensating for p35 through in utero electroporation partially rescues metformin-impaired neuronal migration and development. In summary, our study reveals that metformin disrupts neocortex development by inhibiting neuronal progenitor proliferation, neuronal migration, cortical layering, and cortical neuron maturation, likely via ERK and p35/CDK5 inhibition. Consequently, our findings advocate for caution in metformin usage during pregnancy, given its potential adverse effects on fetal brain development.

Dinaciclib inhibits the growth of acute myeloid leukemia cells through either cell cycle-related or ERK1/STAT3/MYC pathways

Although immature differentiation and uncontrolled proliferation of hematopoietic stem cells are thought to be the primary mechanisms of acute myeloid leukemia (AML), the pathophysiology in most cases remains unclear. Dinaciclib, a selective small molecule targeting multiple cyclin-dependent kinases (CDKs), is currently being evaluated in oncological clinical trials. Despite the proven anticancer potential of dinaciclib, the differential molecular mechanisms by which it inhibits the growth of different AML cell lines remain unclear. In the current study, we treated HL-60 and KG-1 AML cell lines with dinaciclib and investigated the potential mechanisms of dinaciclib-induced AML cell growth inhibition using flow cytometry and western blotting assays. Data from HL-60 and KG-1 AML cells were validated using human primary AML cells. The results showed that the growth inhibitory effect of dinaciclib was more sensitive in HL-60 cells (IC50: 8.46 nM) than in KG-1 cells (IC50: 14.37 nM). The protein decline in Cyclin A/B and CDK1 and cell cycle arrest in the G2/M phase were more profound in HL-60 cells, corresponding to its growth inhibition. Although the growth inhibition of KG-1 cells by dinaciclib was still pronounced, the cell cycle-associated proteins were relatively insensitive. In addition to cell cycle regulation, the activation/expression of ERK1/STAT3/MYC signaling was significantly reduced by dinaciclib in KG-1 cells compared with that in HL-60 cells. Regarding the results of primary AML cells, we observed ERK1/STAT3/MYC inhibition and cell cycle regulation in different patients. These findings suggest that the cell cycle-associated and ERK1/STAT3/MYC signaling pathways might be two distinct mechanisms by which dinaciclib inhibits AML cells, which could facilitate the development of combination therapy for AML in the future.

BMS-201620: a selective beta 3 agonist

A series of N-(4-hydroxy-3-methylsulfonanilidoethanol)arylglycinamides were prepared and evaluated for their human beta3 adrenergic receptor agonist activity. SAR studies led to the identification of BMS-201620 (39), a potent beta3 full agonist (Ki = 93 nM, 93% activation). Based on its favorable safety profile, BMS-201620 was chosen for clinical evaluation.

Symmetrical body-weight distribution training in stroke patients and its effect on fall prevention

OBJECTIVE

To determine the role of symmetrical body-weight distribution training in preventing falls among patients with hemiplegic stroke.

DESIGN

A prospective study using a standing biofeedback trainer.

SETTING

Hospital-based rehabilitation units.

PATIENTS

Fifty-four patients with hemiplegic stroke (30 in the training group, 24 in the control group).

INTERVENTIONS

Conventional stroke rehabilitation program, plus symmetrical standing training and repetitive sit-to-stand training, with a standing biofeedback trainer. Training effect was evaluated by assessing the sit-to-stand performance and comparing the occurrence of falls in the 2 groups at a 6-month follow-up.

MAIN OUTCOME MEASURES

Occurrence of falls, sit-to-stand performance, including body-weight distribution, rate of rise in force, and sway in center of pressure (COP).

RESULTS

Significant improvement in sit-to-stand performance was found in patients in the training group. Body weight was distributed more symmetrically in both legs, with less mediolateral sway in the COP when rising and sitting down. The mean difference in body-weight distribution between the left and right legs while subjects were rising from a chair significantly decreased, from 49.5% +/- 18.9% to 38.6% +/- 15.8% of body weight (BW) (p < .005). The rate of rise in force while rising from a chair significantly increased, from 28.3% +/- 13.5%BW/s to 53.6% +/- 20.5%BW/s (p < .001). At the 6-month follow-up, 10 of 24 patients (41.7%) in the control group had fallen, compared with only 5 of 30 patients (16.7%) in the training group (p < .05).

CONCLUSIONS

Symmetrical body-weight distribution training may improve sit-to-stand performance and, consequently, decrease the number of falls by stroke patients.

Pulmonary function and spinal characteristics: their relationships in persons with idiopathic and postpoliomyelitic scoliosis

OBJECTIVE

To identify what influence the various features of spinal deformity have on pulmonary function in persons with idiopathic and the postpoliomyelitic scoliosis.

DESIGN

Prospective, cohort, observational study with clinical and radiologic evaluations.

SETTING

Hospital-based rehabilitation units.

PATIENTS

Forty-four patients with idiopathic scoliotis and 16 with postpoliomyelitic scoliotis. Each group was divided into subgroups: normal and abnormal pulmonary function.

INTERVENTION

Clinical and radiologic evaluation of spinal deformity, full pulmonary functional test and respiratory muscle strength were performed. Presence of dyspnea on exertion and low back pain (LBP) was recorded.

MAIN OUTCOME MEASURES

Pulmonary function: spirometry, lung volume test, and diffusing capacity. Respiratory muscle strength: maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP). Presence of dyspnea on exertion (DOE), and LBP were also recorded. Characteristics of spinal deformity: direction of convexity, uppermost vertebra, number of involved vertebrae, Cobb angle, the apical vertebra, degree of rotation at the apical vertebra, type of scoliotic curve, and presence of balanced spine and pelvic obliquity. Chi-square analyses and Mann-Whitney U test for between-groups comparisons. Spearman's rho correlation coefficient to determine the existence and magnitude of a relationship.

RESULTS

We found significant differences between the idiopathic and postpoliomyelitis groups in the degree of rotation at the apical vertebra, MIP, average percentage of predicted vital capacity, residual volume/total lung capacity, presence of double or triple curves, pelvic obliquity, and DOE. Between the idiopathic scoliotis subgroups we found significant differences in the uppermost vertebra and number of vertebrae in the scoliotic curve. Between the subgroups of the postpoliomyelitis group were significant differences in the location of the apical vertebra and the uppermost vertebral body of scoliotic curve. In the idiopathic group, pulmonary function was mostly related to scoliotic angle, number of vertebrae in the scoliotic curve, location of the uppermost vertebra, and the patients' age; MIP and MEP were negatively related to the scoliotic angle and degree of rotation of apical vertebra. In the postpoliomyelitis group, pulmonary function was mostly related to scoliotic angle, kyphotic angle, location of the uppermost vertebra of the scoliotic curve, and age.

CONCLUSION

No single factor can predict the severity of impairment in scoliotic patients' pulmonary function. In both groups, severity of pulmonary impairment was related to the combined features of the spinal deformity. However, uppermost vertebra, scoliotic angle, and patient's age may play important roles influencing pulmonary function in both groups.

Objective comparison of shoulder dysfunction after three neck dissection techniques

A prospective study with subjective evaluation of shoulder pain and objective evaluation of shoulder muscle strength by isokinetic testing and electromyographic and electroneurographic studies of spinal accessory nerve function was performed on patients who had undergone neck dissection procedures. Twenty-one patients with head and neck cancer were enrolled in this study. Three types of neck dissection were performed: 7 selective neck dissections, 9 modified radical neck dissections, and 5 radical neck dissections. All patients who underwent radical neck dissection had shoulder pain, and 80% of them had shoulder droop after the operation. In the patients who underwent selective neck dissection, the electromyographic findings of the spinal accessory nerve were relatively normal. Their shoulder strength was sometimes decreased at I month after operation, but it had returned to preoperative strength by the 6-month follow-up visit. These findings suggested that patients who underwent selective neck dissection had the least damage to spinal accessory nerve function and the least shoulder disability after neck dissection.

Correlation of polyelectromyographic patterns and clinical upper motor neuron syndrome in hemiplegic stroke patients

OBJECTIVE

To investigate the correlation between movement patterns, measured by polyelectromyography (PEMG), and clinical upper motor neuron (UMN) syndrome in stroke patients.

DESIGN

PEMG patterns, recorded from pairs of flexor-extensor muscles during voluntary maneuvers, and motor outcomes were assessed approximately 1 month after stroke (early stage). Motor outcomes were reassessed 6 months later (late stage).

PARTICIPANTS

Thirty-nine hemiplegic stroke patients and 18 healthy control subjects.

MAIN OUTCOME MEASURES

Passive stretch reflexes (PSRs), Brunnstrom's stages, and walking ability.

RESULTS

Six PEMG patterns, varying from complete reciprocal to complete synchrony, were identified. Higher PEMG pattern scores were associated with better Brunnstrom's stages (r > .80), walking ability (r > .39), and some PSRs (r < -.37). PEMG patterns could separate patterns 1 and 2 from patterns 3 and 4 for patients with early Brunnstrom's stages 1 and 2. Patterns 1 and 2 (reduced agonist electromyographic activities) indicated weakness and resulted in the worst motor outcomes. Patterns 3 and 4 (cocontraction and coactivation) indicated spasticity and associated synergistic movements. Patients with patterns of 5 and 6 (reciprocal electromyographic activities) had more selective motor control.

CONCLUSIONS

PEMG patterns correlate with clinical UMN syndromes and may allow treatment strategy planning on the basis of underlying motor control, as well as the prediction of final motor outcomes soon after stroke, even in patients who cannot move their legs initially.

Resistive inspiratory muscle training: its effectiveness in patients with acute complete cervical cord injury

OBJECTIVE

To evaluate if resistive inspiratory muscle training (RIMT) can improve lung function in patients with complete tetraplegia within half a year after trauma.

DESIGN

A prospective study. The experimental patients received training with a Diemolding Healthcare Division inspiratory muscle trainer for 15 to 20 minutes per session, twice per day, 7 days a week for 6 weeks.

SETTING

Hospital-based rehabilitation units.

PATIENTS

Twenty patients who were in their first 6 months of complete cervical cord injury were randomly enrolled into RIMT (10 patients) and control (10 patients) groups.

MAIN OUTCOME MEASURE

Spirometry, lung volume test, maximal inspiratory pressure, maximal expiratory pressure, and modified Borg scale measurements at rest were performed before training and at the end of 6 weeks of training.

RESULTS

Most of the pulmonary parameters showed statistically significant improvements within the RIMT and control groups, but the improvements were greater in the RIMT group. In addition, the improvements in total lung capacity, total lung capacity predicted percentage, vital capacity, minute ventilation, forced expiratory volume in 1 second predicted percentage, and the resting Borg scale in the RIMT group showed significantly greater improvement.

CONCLUSION

RIMT can improve ventilatory function, respiratory endurance, and the perceived difficulty of breathing in patients with complete cervical spinal cord injury within half a year after trauma.

Balance evaluation in hemiplegic stroke patients

BACKGROUND

Decreased equilibrium in standing and walking is a common problem associated with hemiplegic stroke patients. Stroke patients with balance problems are prone to falls. In addition to spatial recognition, the appropriate pattern of muscle activity to preserve balance depends on sensory and motor processes. Previous reports have mentioned that the right posterior parietal cortex seems to be predominantly involved in spatial integration. We therefore wanted to conduct a study to quantify and compare the balance control between right hemispheric stroke and left hemispheric stroke patients.

METHODS

Thirty hemiplegic stroke patients (14 right, 16 left) and 15 age-matched healthy subjects were included in this study. The objective measurement of the basic components of balance control was performed using the SMART Balance Master. The motor status of the hemiplegic limbs was evaluated by Brunnstrom staging. The functional outcome of the stroke patients was evaluated by the functional independence measure (FIM).

RESULTS

The balance function of stroke patients was significantly worse as compared to that of the healthy subjects especially in dynamic stability. However, different from the other reports, our right hemispheric stroke patients had better balance function than our left hemispheric patients. The locomotion and mobility scores of the FIM were also better in the right hemispheric stroke patients.

CONCLUSION

This result suggested that the motor function of the healthy limbs of stroke patients may play an important role in their balance function. The results of this study may provide a guide for prescribing a more efficient rehabilitation program for stroke patients.

Clinical trial of electrical acupuncture on hemiplegic stroke patients

To assess the efficacy of electrical acupuncture in the rehabilitation of patients with hemiplegia in stroke, we randomized 128 patients within 2 wk of stroke onset to receive either comprehensive rehabilitation plus electrical acupuncture (n = 59) or comprehensive rehabilitation only (n = 59). Electrical acupuncture was administered by electrical stimulation of acupuncture points through adhesive surface electrodes five times per week. Neurological status (Brunnstrom's stage) and the Chinese version of the Functional Independence Measure were assessed before treatment and at discharge. Patients treated with electrical acupuncture had a shorter duration of hospital stay for rehabilitation and better neurological and functional outcomes than the control group had, with a significant difference in scores for self-care and locomotion (P = 0.02). This result did not postulate the previous study that acupuncture therapy for stroke patients should depend on needle manual and "de qi" response. We suggest that electrical acupuncture through adhesive surface electrodes in conjunction with current optimal rehabilitation programs is a convenient and effective therapy for stroke patients.

Central representation of phantom limb phenomenon in amputees studied with single photon emission computerized tomography

To explore the possible mechanisms of phantom limb discomfort after amputation, three amputees with phantom limb pain were studied. This study examined the change of regional cerebral blood flow using technetium-99m hexamethylpropyleneamine oxime-single photon emission computerized tomography, which was arranged at the time of severe phantom limb discomfort and after the discomfort subsided or was completely relieved. Nine representative transverse slices parallel to the orbitomeatal line were selected for quantification. The cortical ribbon (2-cm thickness) was equally subdivided into 12 symmetrical pairs of sector regions of interest in each slice. The irregularly shaped regions of interest were drawn manually around the right thalamus and basal ganglion and then mirrored to the left thalamus and basal ganglion. The contralateral to ipsilateral ratio of regional cerebral blood flow for each area was calculated. The intensity of phantom limb pain was evaluated on a 0 to 10 visual analog scale. In Cases 1 and 2, the contralateral to ipsilateral regional cerebral blood flow ratios of multiple areas of the frontal, temporal, or parietal lobes were increased at the time of more severe phantom limb pain, and the ratios were normalized or even decreased when the phantom limb pain subsided. In Case 3, increased contralateral to ipsilateral regional cerebral blood flow ratios were also found over the frontal, temporal, and parietal lobe. However, most of the increased regional cerebral blood flow ratios of regions of interest in the first study persisted in the follow-up study. Also, the regional cerebral blood flow ratios of greater number of regions of interest of the same gyrus and new gyrus were increased. There was no significant right-left difference of regional cerebral blood flow over bilateral thalami and basal ganglia in all three cases. The results suggested that phantom limb pain might be associated with cortical activation involving the frontal, temporal, or parietal cortex, and it may imply the possibility of the existence of an ascending polysynaptic pathway that conveys the uncomfortable phantom limb sensation to the cerebral cortex. These findings may also indicate that reorganization of the cortical blood flow occurs in amputees. However, it is still difficult to conclude that the changes in regional cerebral blood flow were attributable directly to pain. With no comparison group of amputees and because of the small number of cases, it is hard to generalize about cerebrocortical involvement in phantom pain, and it is possible that the findings represent a normal phenomenon seen after 'amputation. Another possibility is that the findings represent increased arousal caused by pain rather than an intrinsic pain pathway. Further study is worthwhile.

The sit-to-stand movement in stroke patients and its correlation with falling

OBJECTIVE

To use kinetic assessment of the sit-to-stand movement as a means of sorting out those stroke patients at risk for falling.

DESIGN

A retrospective study, using a force platform to assess sit-to-stand performance and to determine its correlation with falls in stroke patients.

SETTING

Hospital-based rehabilitation units.

METHODS

Thirty-three stroke patients (18 fallers, 15 nonfallers) and 25 age-matched healthy subjects were included in this study. Subjects sat in an adjustable chair with their feet on two force plates and performed the standing up/sitting down movement at a self-paced, comfortable speed.

RESULTS

The rate of rise in force (dF/dT) was significantly lower in stroke fallers than in stroke nonfallers and healthy subjects (23.78+/-17.38, 55.23+/-31.24, and 85.96+/-42.4 percent body weight per second, respectively [p < .005]). The center of pressure sway in mediolateral direction during rising/ sitting down was much greater in stroke fallers than in stroke nonfallers or healthy subjects (p < .05). Body weight distribution was asymmetric on the feet of stroke patients, with much more body weight on their sound side.

CONCLUSIONS

The significantly lower rate of rise in force and greater postural sway while rising/sitting down may be useful in identifying stroke patients who are at risk for falling.

A therapeutic trial of acupuncture in neurogenic bladder of spinal cord injured patients--a preliminary report

Eighty patients with spinal cord injury (SCI) and neurogenic bladder were studied. Among them, 28 (70%) cases in the control group and 32 (80%) cases in the electroacupuncture group achieved ultimately balanced voiding and were selected for further analysis. The acupuncture group received electroacupuncture at four acupoints: Chung Chi (Conception Vessel CV3), Kuan Yuan (CV4), and bilateral Tzu Liao (Urinary Bladder UB32), in addition to conventional intermittent catheterization program (ICP). Whereas the control group underwent conventional bladder training program with ICP only. The results revealed that the time of achieving balanced voiding was statistically significantly shorter with electroacupuncture than in the control group: 57.1 +/- 22.6 vs 85.2 +/- 27.4 days (P < 0.005) for upper motor neuron lesions, and 55.4 +/- 22.6 vs 83.4 +/- 26.1 days (P < 0.01) for lower motor neuron lesions. However, there was almost no difference between upper motor neuron lesions and lower motor neuron lesions. When acupuncture commenced was alos a factor to influence the results. Those who received acupuncture within 3 weeks after injury had significantly shortened the total days to achieve a balanced bladder, as compared to those who received acupuncture 3 weeks after injury (46.6 +/- 13.2 vs 65.8 +/- 15.4 days, P < 0.005). Our study implied that acupuncture might be beneficial in the management of neurogenic bladder of SCI, and the earlier the patient received electro-acupuncture therapy, the sooner the bladder balanced. On the other hand, we also found that complete spinal cord injury, either with pronounced detrusor-sphincter dyssynergia in upper motor neuron lesion or with persistent areflexic bladder in lower motor neuron-lesion, was not affected by acupuncture.

New quantitative and qualitative measures on functional mobility prediction for stroke patients

The purpose of this study was to explore whether we could provide supportive laboratory evidence for clinical observations that a stroke patient has lost functional mobility/locomotion capability based on dynamic balance responses (centre of pressure, COP sway patterns) and motor control activities (EMG patterns) during the motor task of sit-to-stand. A computerized controlled dynamic postural control assessment system was developed and used in this study. Various dynamic balance indices were introduced and derived from COP sway patterns expressed in four domains (i.e. space, time, force, and frequency). Motor control was assessed by multi-channel surface electromyography of each side of the lower limb during the same motor task. The functional mobility capability was evaluated using a traditional FIM method. Fourteen stroke patients with right hemiplegia and nine healthy elderly were recruited as the experimental and control groups respectively. Muscle activity was recorded for quadriceps, hamstrings, anterior tibialis, and triceps surae muscles and used for analysis. Centre of pressure sway patterns and ground reaction forces were registered. All signals were synchronized at 'seat-off'. Surface electromyographic patterns of activities recorded during sit-to-stand and dynamic balance indices computed from centre of pressure sway patterns were categorized and compared with the functional mobility scores. The results show that both the motor control patterns and dynamic balance indices correlated well to the extent of mobility impairment evaluated using the traditional FIM method. An important conclusion for rehabilitation medicine is that the functional mobility capability of stroke patients may be quantified analytically using dynamic balance indices and visualized graphically through EMG motor patterns.

The immediate effectiveness of electrical nerve stimulation and electrical muscle stimulation on myofascial trigger points

This study is designed to investigate the immediate effectiveness of electrotherapy on myofascial trigger points of upper trapezius muscle. Sixty patients (25 males and 35 females) who had myofascial trigger points in one side of the upper trapezius muscles were studied. The involved upper trapezius muscles were treated with three different methods according to a random assignment: group A muscles (n = 18) were given placebo treatment (control group); group B muscles (n = 20) were treated with electrical nerve stimulation (ENS) therapy; and group C muscles (n = 22) were given electrical muscle stimulation (EMS) therapy. The effectiveness of treatment was assessed by conducting three measurements on each muscle before and immediately after treatment: subjective pain intensity [(PI) with a visual analog scale], pressure pain threshold [(PT) with algometry], and range of motion [(ROM) with a goniometer] of upper trapezius muscle (lateral bending of cervical spine to the opposite side). When the effectiveness of treatment was compared with that of the placebo group (group A), there was significant improvement in PI and PT in group B (P < 0.01) but not in group C (P > 0.05). The improvement of ROM was significantly more in group C (P < 0.01) as compared with that in group A or group B. When each group was divided into two additional subgroups based on the initial PI, it was found that ENS could reduce PI and increase PT significantly (P < 0.05), but did not significantly (P > 0.05) improve ROM, as compared with the placebo group for both subgroups. EMS could significantly (P < 0.05) improve ROM, but not PT, better than the placebo groups, for either subgroup. It could reduce PI significantly more (P < 0.05) than placebo controls only for the subgroup with mild to moderate pain, but not with severe pain. For pain relief, ENS was significantly better (P < 0.05) than EMS; but for the improvement of ROM, EMS was significantly better (P < 0.05) than ENS. It is concluded that ENS is more effective for immediate relief of myofascial trigger point pain than EMS, and EMS has a better effect on immediate release of muscle tightness than ENS.

Comparison of balance responses and motor patterns during sit-to-stand task with functional mobility in stroke patients

This study was undertaken to explore whether we could provide supportive laboratory evidence for the clinical observations that a stroke patient has lost functional mobility/locomotion capability based on dynamic balance responses (center of force sway patterns) and motor control activities (electromyography patterns) during the motor task of sit-to-stand. A computerized controlled dynamic postural control assessment system was developed and used in this study. Various dynamic balance indexes were introduced and derived from center of force sway patterns expressed in four domains (space, time, force, and frequency). Motor control was assessed by multichannel surface electromyography of each side of the lower limb during the same motor task. The functional mobility capability was evaluated using the traditional FIM method. Fourteen stroke patients with right hemiplegia and nine healthy elderly individuals were recruited as the experimental and control groups, respectively. Muscle activity was recorded for quadriceps, hamstrings, anterior tibialis, and triceps surae muscles and was used for analysis. Center of force sway patterns and ground reaction forces were registered. All signals were synchronized at "seat-off." Surface electromyographic patterns of activities recorded during sit-to-stand and dynamic balance indexes computed from center of force sway patterns were categorized and compared with the functional mobility scores. Results show that both the motor control patterns and dynamic balance indexes correlated well to the extent of mobility impairment evaluated using the traditional FIM method. An important conclusion for rehabilitation medicine is that the functional mobility capability of stroke patients may be expressed numerically using dynamic balance indexes and visualized graphically through electromyographic motor patterns.

Spontaneous electromyographic potentials in cervical cord-injured patients are related to dysesthetic pain

A total of 61 traumatic cervical cord-injured patients were included in this study. Needle electromyography and nerve conduction study were performed at 6 to 24 weeks postinjury. Correlation between the presence of spontaneous electromyographic potentials and the presence of dysesthetic pain, as well as other clinical characteristics including age, gender, level of injury, severity of injury, spasticity, duration of injury, and performance of spinal surgery was statistically analyzed. Of the 31 patients who had spontaneous electromyographic potentials in their hands, 27 (87%) had dysesthetic pain in their limbs. Only 9 (30%) of the other 30 patients without spontaneous potentials developed dysesthetic pain. A significant correlation (P < 0.001) between the presence of spontaneous electromyographic potential and dysesthetic pain was found. The presence of spontaneous electromyographic potentials was also significantly (P < 0.05) correlated with severity of injury but not with age, gender, injury level, duration of injury, operation, and spasticity. In conclusion, the presence of spontaneous electromyographic potentials in cervical cord-injured patients was significantly related to the presence of dysesthetic pain. They occurred more often in patients with more severe injury.

Aminodiol HIV protease inhibitors. Synthesis and structure-activity relationships of P1/P1' compounds: correlation between lipophilicity and cytotoxicity

A series of novel aminodiol inhibitors of HIV protease based on the lead compound 1 with structural modifications at P1' were synthesized in order to reduce the cytotoxicity of 1. We have observed a high degree of correlation between the lipophilicity and cytotoxicity of this series of inhibitors. It was found that appropriate substitution at the para position of the P1' phenyl group of 1 resulted in the identification of equipotent (both against the enzyme and in cell culture) compounds (10l, 10m, 10n, and 15c) which possess significantly decreased cytotoxicity.

Prediction of reflex sympathetic dystrophy in hemiplegic patients by electromyographic study

BACKGROUND AND PURPOSE

This study was designed to investigate the correlation between reflex sympathetic dystrophy syndrome (RSDS) in hemiplegic patients and spontaneous electromyographic (EMG) activity, as well as to determine the predictive value of spontaneous EMG activity in early diagnosis of RSDS.

METHODS

An EMG and nerve conduction velocity study of the weak upper limb was conducted on 70 hemiplegic patients at 3 to 4 weeks after cerebrovascular disease (either cerebral hemorrhage or infarction). Clinical assessment for development of the RSDS was done during the following 6 months. The correlation of RSDS development with the presence of spontaneous EMG activity and certain clinical parameters (including sex, age, side affected, cause of stroke, sensory impairment, spasticity, and shoulder subluxation) was analyzed statistically.

RESULTS

Of the 46 patients who exhibited spontaneous activity, 30 (65%) developed clinical RSDS in their hemiplegic upper extremity, whereas only 1 (4%) of the other 24 patients with no spontaneous EMG activity developed clinical RSDS within 6 months after the onset of hemiplegia (P < .001). The correlation of RSDS development with the presence of shoulder subluxation and sensory impairment in the hemiplegic side was statistically significant. Neither age, sex, severity of spasticity, nor etiology of stroke had a significant correlation with the development of clinical RSDS.

CONCLUSIONS

There is significant correlation between the presence of spontaneous EMG activity and the development of clinical RSDS in the hemiplegic upper extremity after stroke. It is concluded that spontaneous EMG activity in the hemiplegic hands of stroke patients might be a good predictor of the future development of clinical RSDS.

Estrogen dose required to maintain parathyroid hormone mediated bone gain in osteopenic ovariectomized rats is probably higher than in preventive treatment with estrogen

Successful prevention of bone loss in ovariectomized rats with 17 beta-estradiol (E2) at 10 micrograms/kg/d has been reported. Here we show that E2 dose twice that much is not enough to maintain PTH(1-34) mediated bone gain. Three-month-old female Wistar rats were ovariectomized and fed with regular rodent chow and water ad libitum. Three months later they were divided into 9 groups (5-8 per group) and treated cyclically with PTH(1-34) (20 micrograms/kg/d sc, 5d/w for 3w) and E2 (20 micrograms/kg/d sc, 5d/w for 4w). There were also a baseline group and five vehicle control groups. Cancellous bone volume (Cn.BV/TV) of distal femoral metaphyses was measured by computer-aided histomorphometry on trichrome stained thin sections, and 24-hour fasted urine was analyzed for pyridinoline/creatinine (PYR/CREA) by immunoassay. Histomorphometric results showed that PTH(1-34) progressively increased Cn.BV/TV but E2 failed to maintain them. Urinary PYR/CREA results showed that E2-treated groups had lower values. We conclude that E2 dose > 20 micrograms/kg/d is required to maintain the PTH mediated bone gain.

Cyclical treatment of osteopenic ovariectomized adult rats with PTH(1-34) and pamidronate

Administration of PTH(1-34) at low intermittent doses stimulates bone formation in vivo. However, the new bone is quickly resorbed after drug withdrawal. Following the concept of lose, restore, and maintain, we studied the possibility of maintaining the PTH(1-34)-mediated new bone by APD post-treatment and the effect of a second PTH(1-34)-APD cycle in osteopenic ovariectomized (OVX) adult rats. Eighty OVX rats (6-months-old, 3 months after OVX) and 10 sham-operated rats were divided into nine groups. One OVX group was killed as baseline (BL). Five OVX groups were injected with PTH(1-34) (20 micrograms/kg/day, subcutaneously) for 3 weeks (5 days/week). The remaining two OVX groups and the sham group (S) were injected with saline as controls. One PTH(1-34) group (A) and one control group (B) were then killed. Three PTH(1-34) groups were post-treated with APD injections (250 micrograms/kg/day, subcutaneously) for 5 days; the remaining PTH(1-34) group, the other control group, and group S were injected with saline; and all these groups were left untreated for 3 weeks. At the end, one PTH-APD group (C), the PTH-saline group (D), and the saline-saline group (E) were killed. Another PTH-APD cycle was applied to the remaining two PTH-APD groups, with group F killed after the second PTH treatment and group G killed after two complete cycles. We found a 90% increase in cancellous bone volume (Cn.BV/TV) and a 28% increase in trabecular thickness (Tr.Th) in group A over group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrical injury--clinical report of 67 cases

We have reviewed 67 patients of electrical burns treated at Linkou Burn Center of Chang Gung Memorial Hospital from January 1988 to April 1992. There were 2086 acute burn admissions during this period with the proportion of electrical injuries being 3.2%. Their age ranged from 13 to 68 years, with 61% in the age group of 20 to 40 years. Sixty-two (92.5%) of our patients were males. Over 60% of these injuries were work-related. The proportion of high voltage electrical injuries was over 60% in our series. All deceased patients and those patients with major complications were in the high voltage electrical injuries group. Low voltage injuries did not leave any major sequelae. In a mean follow-up of 2 years, 83% of our patients could return to the previous job or change to another work. The overall mortality was 6%.

Aminodiol HIV protease inhibitors. 1. Design, synthesis, and preliminary SAR

A series of HIV protease inhibitors containing a novel C2 symmetrical "aminodiol" core structure were prepared from amino acid starting materials. The ability of the aminodiols to inhibit HIV replication in cell culture is comparable to their ability to inhibit the isolated enzyme, a result compatible with good cell membrane penetration by this class of compounds. Optimization of the structure-activity in this series led to aminodiol 9a (Ki = 100 nM; ED50 (HIV-1) = 80 nM) containing P1/P1 benzyl and P2/P2 Boc substituents. Compound 9a is a selective inhibitor of HIV protease versus other aspartyl proteases such as human renin, human cathepsin D, and porcine pepsin. In addition, 9a is equipotent against HIV-1 and HIV-2 in cell culture and demonstrates similar activity in infected T-lymphocytes and PBMCs. After i.v. and oral administration in rats, 9a displayed significant oral bioavailability (ca. 40%) and a promising plasma elimination half-life (4 h).

Clinical and biochemical differences in patients with pure calcium oxalate monohydrate and calcium oxalate dihydrate kidney stones

To examine the factors and patient characteristics predisposing to formation of calcium oxalate monohydrate or calcium oxalate dihydrate kidney stones, we compared blood and 24-hour urine tests, gender distribution and patient age in 2 groups of patients with pure calcium oxalate monohydrate (422) and calcium oxalate dihydrate (68) stones treated at the lithotripsy unit of the Wellesley Hospital and University of Toronto during 4 years. The calcium oxalate monohydrate group included relatively more women (31% versus 16% in the calcium oxalate dihydrate group, chi-square 7.89, p = 0.005). Patients were older in the calcium oxalate monohydrate group (59 +/- 13 versus 51 +/- 13 years, p = 0.001). The calcium oxalate monohydrate group had lower urinary calcium (4.19 +/- 2.34 versus 7.19 +/- 3.38 mmol. per day, p < 0.0001), calcium oxalate relative saturation rate (6.9 +/- 3.9 versus 8.9 +/- 3.3, p = 0.001), brushite relative saturation rate (0.7 +/- 0.8 versus 1.2 +/- 0.9, p = 0.0001) and urinary pH (5.72 +/- 0.75 versus 5.93 +/- 0.72). When corrected for patient age and gender, the calcium oxalate dihydrate group still had higher urine calcium levels. Higher urine pH in the calcium oxalate dihydrate group was age-related. In summary, we present evidence that calcium oxalate dihydrate stones are relatively more common among younger male patients with higher urine calcium levels and higher urine pH.

A comparison of five preparations of synthetic monosodium urate monohydrate crystals

We conducted preliminary crystallographic investigations and biologic studies on 5 synthetically grown preparations of monosodium urate monohydrate (MSUM) crystals including one preparation of urate spherulites. The 5 crystal preparations exhibited wide variations in morphology, size, surface area, and ultrastructure, but only a few changes in their biologic effects. When injected intraarticularly, urate spherulites were less phlogistic than most acicular forms. Since crystal-cell interactions and inflammatory responses are influenced by crystal size, morphology, and surface characteristics, standardization of methods of preparing MSUM crystals is, therefore, important, particularly when analyzing and comparing results from different research laboratories.

Concentration dependence of fluorine impurity spin-lattice relaxation rate in bone mineral

The concentration dependence of the fluoride ion spin-lattice relaxation rate has been observed by nuclear magnetic resonance experiments on samples of defatted and dried bone. The 19F spin-lattice relaxation rates increased linearly with the bone fluoride concentration. Different results were obtained from trabecular than from cortical bone. For the same macroscopic fluoride content per gram of bone calcium, the relaxation rate is significantly faster in cortical bone. Relaxation rates in cortical bone samples prepared from both rats and dogs were apparently controlled by the same species-independent processes. For samples from beagle dogs, the bulk fluoride concentrations measured by neutron activation analysis were 3.1 +/- 0.3 times greater in trabecular bone than in the corresponding cortical bone. The beagle spin-lattice relaxation data suggest that the microscopic fluoride concentrations in bone mineral were 1.8 +/- 0.4 times greater in trabecular bone than in cortical bone. It is concluded that the accumulation of fluoride impurities in bone mineral is non-uniform.

Aneurysmal subarachnoid hemorrhage. Report of 219 cases in Chang Gung Memorial Hospital

Two hundred and nineteen cases with aneurysmal subarachnoid hemorrhage treated at Chang Gung Memorial Hospital from January 1986 to December 1989 were studied. Their ages ranged from 19 to 76, with a mean of 55 +/- 16 years. About one third of the cases occurred in the age group of 50 to 59 years. Females were predominant with a female to male ratio of 2:1, but there was a male predominance below age 40. The most common site of aneurysm was the anterior communicating artery. Rebleeding, delayed vasospasm with cerebral infarction, and hydrocephalus were the main causes of death or disability. The mean follow-up of 6 months for the whole group showed a 59% favorable outcome, 13% severe disability and a 28% mortality. For those 166 patients who underwent surgical treatment, there was 8% mortality.

Effects of pyrophosphatase on dissolution of calcium pyrophosphate dihydrate crystals

Understanding the dissolution mechanisms involved in calcium pyrophosphate dihydrate (CPPD) crystals may prove important for the development of therapy for CPPD arthropathy. We demonstrate that yeast pyrophosphatase effectively dissolved CPPD crystals in solutions. Maximum enzymatic dissolution of CPPD crystals was achieved at neutral pH and when the enzyme had access to the crystal surface. The enzymatic dissolution of CPPD crystals was highly dependent on ambient [Mg++] and [Ca++]. The stimulating effects of Mg++ on crystal dissolution in the presence of the enzyme is due to stimulation of pyrophosphatase activity and to enhanced direct release of pyrophosphate ions from the crystal surface. The inhibiting effect of Ca++ on crystal dissolution by the enzyme is mainly due to the suppression of pyrophosphatase activity.

Effects of fluoride on rat cancellous bone

Female Wistar rats were divided into four groups each fed ad libitum regular rodent chow and fluoridated water at four levels (0, 2, 4, 6 mmol/l) for 3 months. There were significant differences in ash weights between control and fluoridated vertebrae (P less than 0.01). Intact bone fluoride (F) values observed were: 0.04 +/- 0.01% fat-free dry weight (ffdw) for control vertebrae and 0.22-0.34 +/- 0.03% ffdw for fluoridated vertebrae. Deproteinized fluoridated vertebral bone had significantly lower specific surface area (SSA) (from 100 +/- 19 m2/g, P less than 0.01, down to 80 +/- 20 m2/g, P less than 0.001) than the control group (120 +/- 10 m2/g); a finding in support of our hypothesis that more of the bone mineral units in fluoridated bone are older (hence denser) than in normal bone. Static morphometric analysis of toluidine blue-stained sections of the femoral metaphyses showed that both cancellous bone volume/tissue volume (Cn-BV/TV) and trabecular thickness (Tb.Th) increased linearly with NaF dosage (R = 0.99 and 0.97, respectively); with Cn-BV/TV increasing from 21 +/- 7 to 33 +/- 6% (P less than 0.01) and Tb.Th from 76 +/- 8 to 98 +/- 9 microns (P less than 0.01). Similar Cn-BV/TV results were also obtained from von Kossa-stained sections.(ABSTRACT TRUNCATED AT 250 WORDS)

Field dependence of 19F NMR in rat bone powders

The 19F NMR properties of fluoridated rat bone powder samples have been studied in several external magnetic fields. The results show a characteristic field dependence, related to the strength of chemical shift interactions compared to dipole-dipole interactions. While the free induction decay shape is relatively insensitive to the 19F bone mineral concentration, the spin-lattice relaxation time decreases with increasing 19F concentration. Multi-exponential spin-lattice relaxation processes indicate that there are at least two chemically inequivalent incorporation sites for fluorine in bone mineral. Evidence for clustering of 19F fluoride impurities in bone mineral is seen in Hahn echo experiments. Sample preparation and handling methods are shown to affect the values of some of the observed NMR parameters.

Fluoride reduces the rate of dissolution of bone

Recently, fluoride has been used in the treatment of osteoporosis in an attempt to rebuild bone lost due to this disease. Fluoride has been shown to have a profound effect on osteoblasts and bone formation. Studies have shown that synthetic fluorapatite is more stable and less soluble than hydroxyapatite. This study was designed to determine the dissolution properties of bones from rats fed a normal diet versus rats fed a high fluoride diet. Intact and deproteinized bones were dissolved in buffered solutions, containing physiological amounts of inorganic Ca and P, at pH 3.4, 4.4 and 5.4. The data demonstrate that fluoridated bones dissolve slower than normal bones, deproteinized bones dissolve faster than intact bones and that the initial rate of dissolution of fluoridated bone is always significantly lower than that of normal bone. This may help to explain the reduced rate of osteoclastic resorption in patients undergoing fluoride therapy.

Crystal associated diseases: role of scanning electron microscopy in diagnosis

As crystals are important etiologic agents for disease, their accurate identification in tissues and body fluids is of utmost importance. This paper surveys the roles of crystals in disease process and outlines current analytical techniques for crystal detection and identification in bone tissues. The value of multiple correlated techniques is demonstrated including scanning electron microscopy, x-ray energy spectroscopy and powder diffraction analysis. The current feasibility of utilizing intermediate voltage scanning transmission analytical electron microscopy to integrate these analytical techniques on the same tissue sample is emphasized.

Pathologic calcium phosphate deposition in model systems

Pathologic calcium phosphate deposition occurs mainly in tissues exposed to highly supersaturated body fluids such as urine and saliva. In vitro models employed to study pathologic calcification include aqueous solutions and hydrogels. Results from studies on de novo formation of various biologic calcium phosphates in aqueous solutions resembling various body fluids have been rewarding. Among others, the de novo results have shown that the formation conditions for each calcium phosphate crystal phase are quite different and are pH dependent, and yet all phases including brushite can form in neutral solutions. This is an important finding because when coupled to the facts that all calcium phosphates including brushite are more soluble in acidic solutions than in neutral ones and that, except in extreme cases of hypercalciuria and/or hyperphosphaturia, body fluid Ca and Pi are not very high, it suggests that in most cases pathologic calcification occurs in alkaline or near neutral milieus. HAP is ubiquitous because it is the most insoluble calcium phosphate crystal phase in alkaline or slightly acidic fluids. In fluids close to neutrality, whitlockite is the next favored, provided that the fluid Mg:Ca ration is neither too low nor too high. Although OCP is only slightly more soluble than whitlockite in near neutral milieus, it is favored only by low fluid Ca:Pi and Mg:Ca ratios and transforms easily to HAP. Except in very acidic milieus, brushite is the most soluble biologic calcium phosphate. Its formation is favored by acidic body fluids with high Ca x Pi or by neutral or slightly alkaline ones with very low Ca:Pi ratio or high Mg:Ca ratio.

Ferrous [Fe++] but not ferric [Fe] ions inhibit de novo formation of calcium pyrophosphate dihydrate crystals: possible relationships to chondrocalcinosis and hemochromatosis

To determine the physical-chemical effects of [Fe++] and [Fe ] on calcium pyrophosphate dihydrate (CPPD) crystal formation de novo, we studied CPPD crystal formation in an established model aqueous solution mixture system using physiological concentrations of Na+, Mg++, Ca++, C1-. We found that [Fe++] greater than 1 microM or [Fe ] greater than or equal to 100 microM inhibits CPPD crystal formation under conditions of [Ca++] = 1.5 mM, [Pi] = 0.1 mM, and [PPi] = 0.1 mM that simulate CPPD formation in vivo. These experiments suggest that at biological concentrations, Fe++ acts to inhibit CPPD formation but that [Fe++] depletion therapy by removal of inhibition effects may facilitate CPPD crystal formation in articular tissues.

Inhibition of calcium pyrophosphate dihydrate crystal formation: effects of carboxylate ions

Proteoglycans are recognized to inhibit calcium pyrophosphate dihydrate (CPPD) crystal formation but the mechanisms are not known. To study the role of carboxylate (-CO2-) ligands, the possible inhibitor effects of sodium acetate, sodium D-glucuronate, disodium malate, and trisodium citrate were studied using solution mixtures containing [Ca2+] = 1.5 mM, [Mg2+] = 0.5 mM, [PPi] = 0.1 mM, [Pi] = 0.1 mM, [Na+] = 140 mM, 37 degrees C, pH 7.4 with or without 9.5 +/- 0.5 mg CPPD (seed) crystals. These studies showed that monocarboxylates (acetate, glucuronate) have little inhibitive effect. Progressively greater inhibition was found with dicarboxylate (malate) and tricarboxylate (citrate) indicating that the arrangement of carboxylate (and sulfate) ligands on proteoglycan is more important than the inhibitory effect of individual ligands.

Fictitious calculi and human calculi with foreign nuclei

The correlative approach employing polarized light microscopy, x-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction and energy dispersive x-ray microanalysis proves to be very useful in identifying fictitious calculi and genuine human calculi with foreign body nuclei. The common artifacts as reported in the literature and observed also by us were minerals, vegetable and plant seeds, cereals, sand grains and sea shell fragments. Two interesting cases involving foreign body nuclei have been reported: one urinary calculus containing a piece of plastic-coated titanium foil in the center; one nasal calculus with a nut as a nucleus. Another common cause for foreign body nucleation is iatrogenic: intrauterine devices, catheters, suture materials and even surgical staples have been reported in the literature to be potent nidi for calculus formation. These cases remind us of the important fact that our body fluids are supersaturated with respect to calcium phosphates and occasionally to other compounds. Hydroxyapatite crystals are readily nucleated by foreign bodies. Whitlockite is involved if the fluid Mg/Ca ratio is in a suitable range, brushite if the fluid is acidic and struvite if there is urea-splitting infection. In urine and other fluids, calcium oxalate and uric acid crystals contribute to the calculus growth.

Effect of synthetic calcium pyrophosphate and hydroxyapatite crystals on the interaction of human blood mononuclear cells with chondrocytes, synovial cells, and fibroblasts

Synthetic calcium pyrophosphate dihydrate crystals and, to a lesser extent, synthetic hydroxyapatite crystals increased the amount of interleukin-1/mononuclear cell factor released by human blood monocytes, as measured by collagenase and prostaglandin E2 production by rabbit chondrocytes, human dermal fibroblasts, and adherent rheumatoid synovial cells. The same crystals also directly induced collagenase and prostaglandin E2 secretion by rabbit chondrocytes, and potentiated the action of interleukin-1/mononuclear cell factor on chondrocytes. These mechanisms may be important in the pathogenesis of the destructive arthropathies associated with these crystals.

Effect of glycosaminoglycans on calcium pyrophosphate crystal formation in collagen gels

Formation of calcium pyrophosphate dihydrate (CPPD) crystals in native collagen gels represent an in vitro model system for the study of pathological cartilage calcification. The conditions under which CPPD forms in collagen gels have been determined. At low Ca X pyrophosphate product, CPPD forms directly. At high Ca X pyrophosphate product, CPPD forms via the amorphous intermediate calcium magnesium pyrophosphate (CMPP). Chondroitin sulfate (CS) inhibits formation of CPPD by both pathways, but apparently by different mechanisms. Direct CPPD formation is inhibited with low potency by CS, apparently by binding of Ca2+ ions. Indirect formation of CPPD is inhibited with high potency by CS, apparently by stabilization of the CMPP intermediate. Comparison of the inhibition of direct CPPD formation by the two glycosaminoglycan species occurring in cartilage proteoglycan showed that CS is a more potent inhibitor than keratan sulfate (KS), in agreement with the greater Ca2+-binding affinity of CS. The increase in KS/CS ration which occurs in human hyaline cartilage with aging may facilitate deposition of CPPD crystals by decreasing the exclusion of pyrophosphate anions.

Formation of octacalcium phosphate and subsequent transformation to hydroxyapatite at low supersaturation: a model for cartilage calcification

By means of X-ray powder diffraction (XRD), octacalcium phosphate (OCP, Ca8H2(PO4)6 X 5H2O, Ca/P = 1.33) has been shown to be a metastable precursor of hydroxyapatite (HA, Ca10(PO4)6(OH)2, Ca/P = 1.67) during de novo HA formation in aqueous solutions containing [CaCl2] = 1.0-2.0 mM and [Na2HPO4] less than or equal to 3 mM, kept at 37 degrees C, 300 mosM and stirred gently at 150 rpm. At the precipitation boundary with initial pH = 7.4, OCP is stable for at least 24 hours when [Ca] = 1.0 mM, and is less stable when [Ca] = 2.0 mM, transforming into a mixture of OCP and HA within 24 hours. Almost complete transformation to HA within 24 hours takes place with high [Ca] and high [Pi]. Statistical analysis of the pH 7.4 precipitation boundary data supports the XRD findings: although [Ca][Pi] values vary significantly (P less than 0.001) with [Ca] (2.70 +/- 0.05 mM2 for [Ca] = 1.0 mM and 2.00 +/- 0.10 mM2 for [Ca] = 2.0 mM), [Ca]1.33[Pi] values do not vary with [Ca] suggesting that the initial precipitation process is 6(1.33 Ca + Pi)----OCP. With initial pH = 7.6, a different precipitation boundary with lower [Ca][Pi] values has been determined. These findings strongly support the fact that rat epiphyseal cartilage fluid which has [CaUF][PiUF] = 2.6 mM2 (UF = ultrafiltrate) and pH 7.6 [2] should be able to support de novo calcification.

Octacalcium phosphate formation in vitro: implications for bone formation

Octacalcium phosphate (OCP, Ca8H2(PO4)6 . 5H2O) has been found in kidney stones and dental calculi and proposed by Brown et al. [1] to be a precursor of hydroxyapatite in bone and teeth formation. As saliva and urine often have acidic pH which favors OCP formation, the question remains then whether OCP can form in the more basic extracellular fluid in the bone milieu. This paper shows that calcium phosphate crystal phases obtained from neutral and pH 7.4 solution mixtures containing [CaCl2] = 0.1-10.0 mM and [Na2HPO4] = 0.1-90.0 mM with 100-300 mosM at 37 degrees C include brushite (CaHPO4 . 2H2O), OCP, and hydroxyapatite (Ca5(OH)(PO4)3). In some solutions OCP transforms into hydroxyapatite after 1 or more days, but brushite has not been observed to transform into OCP. Assuming the extracellular bone fluid has [Ca2+] = 1.0 mM, 300 mosM, and pH 7.4, this work suggests that hydroxyapatite crystals would only form when the ambient [Pi] greater than 5 mM, and that octacalcium phosphate may be a precursor.

Calcium oxalate kidney stones in patients on continuous ambulatory peritoneal dialysis

Kidney stones were passed by ten out of 186 patients with endstage renal disease who were treated with continuous ambulatory peritoneal dialysis (CAPD). Stones from seven patients were examined by x-ray diffraction. In five of them the stones were composed of calcium oxalate monohydrate. The urine calcium oxalate activity product was determined in 44 CAPD patients, eight of whom were stone formers, and compared to that of 120 normal volunteers. In CAPD patients, mean urine ionic-calcium concentration was lower than in normal subjects whereas mean urine ionic-oxalate concentration was significantly higher than in normal subjects. In normal urine samples, the calcium oxalate activity product showed a significant correlation with both the urine ionic-calcium and the ionic-oxalate concentrations. In contrast, in CAPD patients the calcium oxalate activity product correlated with the ionic-calcium concentration but not with ionic-oxalate. Although the urine ionic-calcium concentration is lower in CAPD patients than in normal subjects, it is the relative increase in its concentration which appears to be associated with the increased risk of kidney stone formation in these patients. This relative hypercalciuria seems to follow 1,25(OH)2 vitamin D3 administration.

Pyrophosphate, phosphate ion interaction: effects on calcium pyrophosphate and calcium hydroxyapatite crystal formation in aqueous solutions

The relationship between ambient ionic conditions that favor pyrophosphate (PPi) versus phosphate (Pi) biomineralization is important to understanding the pathogenesis of chondrocalcinosis. We studied aqueous solutions at pH 7.4, 37 degrees C, [Na+] = 140 mM, [Mg+ +] = 0.5 mM, [Ca+ +] = 1.0 or 1.5 mM over a range of pyrophosphate and phosphate concentrations to determine the effect of different ambient concentrations and ratios of Pi/PPi on calcium pyrophosphate dihydrate (CPPD) and calcium hydroxyapatite (HA) crystal formation. We found that the Pi/PPi ratio is an extremely important determinant of the crystal product formed. At low [Pi], CPPD crystal formation is partially inhibited by Pi; at higher [Pi], calcium pyrophosphate, calcium phosphate and calcium pyrophosphate-phosphate complexes amorphous to x-ray diffraction are formed; whereas at still higher [Pi], HA crystal formation partially inhibited by PPi. We conclude that CPPD forms when the ratio [Pi]/[PPi] less than 3 and HA forms when [Pi]/[PPi] greater than 100.