Social isolation recruits amygdala-cortical circuitry to escalate alcohol drinking

How do social factors impact the brain and contribute to increased alcohol drinking? We found that social rank predicts alcohol drinking, where subordinates drink more than dominants. Furthermore, social isolation escalates alcohol drinking, particularly impacting subordinates who display a greater increase in alcohol drinking compared to dominants. Using cellular resolution calcium imaging, we show that the basolateral amygdala-medial prefrontal cortex (BLA-mPFC) circuit predicts alcohol drinking in a rank-dependent manner, unlike non-specific BLA activity. The BLA-mPFC circuit becomes hyperexcitable during social isolation, detecting social isolation states. Mimicking the observed increases in BLA-mPFC activity using optogenetics was sufficient to increase alcohol drinking, suggesting the BLA-mPFC circuit may be a neural substrate for the negative impact of social isolation. To test the hypothesis that the BLA-mPFC circuit conveys a signal induced by social isolation to motivate alcohol consumption, we first determined if this circuit detects social information. Leveraging optogenetics in combination with calcium imaging and computer vision pose tracking, we found that BLA-mPFC circuitry governs social behavior and neural representation of social contact. We further show that BLA-mPFC stimulation mimics social isolation-induced mPFC encoding of sucrose and alcohol, and inhibition of the BLA-mPFC circuit decreases alcohol drinking following social isolation. Collectively, these data suggest the amygdala-cortical circuit mirrors a neural encoding state similar to social isolation and underlies social isolation-associated alcohol drinking.

Thyroid nodules in xeroderma pigmentosum patients: a feature of premature aging

PURPOSE

Xeroderma pigmentosum (XP) is an autosomal recessive disease with defective DNA repair, a markedly increased risk of skin cancer, and premature aging. Reports from North Africa have described thyroid nodules in XP patients, but thyroid nodule prevalence has never been determined in XP patients enrolled in our natural history study at the National Institutes of Health (NIH).

METHODS

We performed thyroid ultrasound examinations on all 29 XP patients examined from 2011 to 2019 and assessed nodule malignancy using the Thyroid Imaging Reporting and Data System. Thyroid nodule prevalence was also obtained from comparison cohorts. DNA sequencing was performed on thyroid tissue from XP patients who had surgery for thyroid cancer.

RESULTS

Thyroid nodules were identified in 18/29 XP patients (62%). The median age of patients with thyroid nodules in our XP cohort (20 years) was younger than that of three comparison groups: 36 years (California study-208 subjects), 48 years (Korean study-24,757 subjects), and 52 years (NIH-682 research subjects). Multiple (2-4) thyroid nodules were found in 12/18 (67%) of the patients with nodules. Autopsy examination revealed follicular adenomas in 4/8 (50%) additional XP patients. DNA sequencing revealed rare mutations in two other XP patients with papillary thyroid cancer.

CONCLUSIONS

XP patients have an increased incidence of thyroid nodules at an early age in comparison to the general population. These finding confirm another premature aging feature of XP.

The neural circuitry of social homeostasis: Consequences of acute versus chronic social isolation

Social homeostasis is the ability of individuals to detect the quantity and quality of social contact, compare it to an established set-point in a command center, and adjust the effort expended to seek the optimal social contact expressed via an effector system. Social contact becomes a positive or negative valence stimulus when it is deficient or in excess, respectively. Chronic deficits lead to set-point adaptations such that reintroduction to the previous optimum is experienced as a surplus. Here, we build upon previous models for social homeostasis to include adaptations to lasting changes in environmental conditions, such as with chronic isolation.

Miliary fibromas in tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis complex (TSC) is a hamartoma syndrome characterized by multiple skin lesions, such as angiofibromas, shagreen patch and miliary fibromas (MiF).

OBJECTIVE

To determine the clinical and histological features of MiF.

METHODS

A retrospective analysis was conducted on 133 adults with TSC. Photography was used to characterize the appearance and location of MiF. Histological features in five skin samples from four individuals were evaluated by a board-certified dermatopathologist.

RESULTS

MiF were observed in 19 of 133 (14%) individuals with TSC. MiF were 1- to 3-mm skin-coloured, sessile papules scattered on the back and rarely buttocks or thighs. Most were scattered in a bilaterally symmetric distribution, but others were asymmetric or associated with a shagreen patch. Histological features of MiF included expansion of the papillary and periadnexal dermis with variable hamartomatous abnormalities involving adjacent epithelial components.

CONCLUSIONS

MiF are distinct from other cutaneous lesions in TSC such as shagreen patches and angiofibromas. Recognition of this entity is important in defining the spectrum of TSC disease and reassuring individuals with TSC that these lesions are benign.

Breakdown of spatial coding and interneuron synchronization in epileptic mice

Temporal lobe epilepsy causes severe cognitive deficits, but the circuit mechanisms remain unknown. Interneuron death and reorganization during epileptogenesis may disrupt the synchrony of hippocampal inhibition. To test this, we simultaneously recorded from the CA1 and dentate gyrus in pilocarpine-treated epileptic mice with silicon probes during head-fixed virtual navigation. We found desynchronized interneuron firing between the CA1 and dentate gyrus in epileptic mice. Since hippocampal interneurons control information processing, we tested whether CA1 spatial coding was altered in this desynchronized circuit, using a novel wire-free miniscope. We found that CA1 place cells in epileptic mice were unstable and completely remapped across a week. This spatial instability emerged around 6 weeks after status epilepticus, well after the onset of chronic seizures and interneuron death. Finally, CA1 network modeling showed that desynchronized inputs can impair the precision and stability of CA1 place cells. Together, these results demonstrate that temporally precise intrahippocampal communication is critical for spatial processing.

Breakdown of spatial coding and interneuron synchronization in epileptic mice

Temporal lobe epilepsy causes severe cognitive deficits, but the circuit mechanisms remain unknown. Interneuron death and reorganization during epileptogenesis may disrupt the synchrony of hippocampal inhibition. To test this, we simultaneously recorded from the CA1 and dentate gyrus in pilocarpine-treated epileptic mice with silicon probes during head-fixed virtual navigation. We found desynchronized interneuron firing between the CA1 and dentate gyrus in epileptic mice. Since hippocampal interneurons control information processing, we tested whether CA1 spatial coding was altered in this desynchronized circuit, using a novel wire-free miniscope. We found that CA1 place cells in epileptic mice were unstable and completely remapped across a week. This spatial instability emerged around 6 weeks after status epilepticus, well after the onset of chronic seizures and interneuron death. Finally, CA1 network modeling showed that desynchronized inputs can impair the precision and stability of CA1 place cells. Together, these results demonstrate that temporally precise intrahippocampal communication is critical for spatial processing.

Pharmacogenomics study of thiazide diuretics and QT interval in multi-ethnic populations: the cohorts for heart and aging research in genomic epidemiology

Thiazide diuretics, commonly used antihypertensives, may cause QT interval (QT) prolongation, a risk factor for highly fatal and difficult to predict ventricular arrhythmias. We examined whether common single-nucleotide polymorphisms (SNPs) modified the association between thiazide use and QT or its component parts (QRS interval, JT interval) by performing ancestry-specific, trans-ethnic and cross-phenotype genome-wide analyses of European (66%), African American (15%) and Hispanic (19%) populations (N=78 199), leveraging longitudinal data, incorporating corrected standard errors to account for underestimation of interaction estimate variances and evaluating evidence for pathway enrichment. Although no loci achieved genome-wide significance (P<5 × 10-8), we found suggestive evidence (P<5 × 10-6) for SNPs modifying the thiazide-QT association at 22 loci, including ion transport loci (for example, NELL1, KCNQ3). The biologic plausibility of our suggestive results and simulations demonstrating modest power to detect interaction effects at genome-wide significant levels indicate that larger studies and innovative statistical methods are warranted in future efforts evaluating thiazide-SNP interactions.

Effects of Rubidium Chloride on the Course of Manic-Depressive Illness

Clinical studies of the effects of rubidium ions on the course of manic-depressive illness are reported. It seems that rubidium tends to increase the length of manic phases and possibly reduces the extremes of mood. Rubidium did not seem to produce any severe side effects in the dose administered, but it has a long biological half-life and caution is still required. Some details of the CSF, RBC, saliva and plasma and urine kinetics are also reported.

Robotic surgery for thyroid disease

While conventional open thyroidectomy techniques are the most widely performed thyroid operation, they produce an anterior neck scar that may be difficult to conceal. The endoscopic thyroidectomy was developed to decrease the cosmetic impact on the patient and has the advantage of reducing the incidence of anterior neck hypoesthesia and paresthesia. However, this procedure has some drawbacks, which motivated surgeons to develop a new operation method. Robotic thyroidectomy is a relatively new approach for treating differentiated thyroid cancer. Over the last few years, robotic thyroidectomies have become more common. Robotic thyroidectomies are a feasible, safe alternative for managing thyroid disease that has remarkable functional benefits beyond those of conventional open methods. The applications for robotic thyroidectomy have expanded to include increasingly advanced cases, which will consequently change the thyroid surgery paradigm in the future.

Intrinsic and integrative properties of substantia nigra pars reticulata neurons

The GABA projection neurons of the substantia nigra pars reticulata (SNr) are output neurons for the basal ganglia and thus critical for movement control. Their most striking neurophysiological feature is sustained, spontaneous high frequency spike firing. A fundamental question is: what are the key ion channels supporting the remarkable firing capability in these neurons? Recent studies indicate that these neurons express tonically active type 3 transient receptor potential (TRPC3) channels that conduct a Na-dependent inward current even at hyperpolarized membrane potentials. When the membrane potential reaches -60 mV, a voltage-gated persistent sodium current (I(NaP)) starts to activate, further depolarizing the membrane potential. At or slightly below -50 mV, the large transient voltage-activated sodium current (I(NaT)) starts to activate and eventually triggers the rapid rising phase of action potentials. SNr GABA neurons have a higher density of I(NaT), contributing to the faster rise and larger amplitude of action potentials, compared with the slow-spiking dopamine neurons. I(NaT) also recovers from inactivation more quickly in SNr GABA neurons than in nigral dopamine neurons. In SNr GABA neurons, the rising phase of the action potential triggers the activation of high-threshold, inactivation-resistant Kv3-like channels that can rapidly repolarize the membrane. These intrinsic ion channels provide SNr GABA neurons with the ability to fire spontaneous and sustained high frequency spikes. Additionally, robust GABA inputs from direct pathway medium spiny neurons in the striatum and GABA neurons in the globus pallidus may inhibit and silence SNr GABA neurons, whereas glutamate synaptic input from the subthalamic nucleus may induce burst firing in SNr GABA neurons. Thus, afferent GABA and glutamate synaptic inputs sculpt the tonic high frequency firing of SNr GABA neurons and the consequent inhibition of their targets into an integrated motor control signal that is further fine-tuned by neuromodulators including dopamine, serotonin, endocannabinoids, and H₂O₂.

Cluster solver for dynamical mean-field theory with linear scaling in inverse temperature

Dynamical mean-field theory and its cluster extensions provide a very useful approach for examining phase transitions in model Hamiltonians and, in combination with electronic structure theory, constitute powerful methods to treat strongly correlated materials. The key advantage to the technique is that, unlike competing real-space methods, the sign problem is well controlled in the Hirsch-Fye (HF) quantum Monte Carlo used as an exact cluster solver. However, an important computational bottleneck remains; the HF method scales as the cube of the inverse temperature, β . This often makes simulations at low temperatures extremely challenging. We present here a method based on determinant quantum Monte Carlo which scales linearly in β , with a quadratic term that comes in to play for the number of time slices larger than hundred, and demonstrate that the sign problem is identical to HF.

Immunocytochemical identification of proteins involved in dopamine release from the somatodendritic compartment of nigral dopaminergic neurons

We examined the somatodendritic compartment of nigral dopaminergic neurons by immunocytochemistry and confocal microscopy, with the aim of identifying proteins that participate in dopamine packaging and release. Nigral dopaminergic neurons were identified by location, cellular features and tyrosine hydroxylase immunoreactivity. Immunoreactive puncta of vesicular monoamine transporter type 2 and proton ATPase, both involved in the packaging of dopamine for release, were located primarily in dopaminergic cell bodies, but were absent in distal dopaminergic dendrites. Many presynaptic proteins associated with transmitter release at fast synapses were absent in nigral dopaminergic neurons, including synaptotagmin 1, syntaxin1, synaptic vesicle proteins 2a and 2b, synaptophysin and synaptobrevin 1 (VAMP 1). On the other hand, syntaxin 3, synaptobrevin 2 (VAMP 2) and SNAP-25-immunoreactivities were found in dopaminergic somata and dendrites Our data imply that the storage and exocytosis of dopamine from the somatodendritic compartment of nigral dopaminergic neurons is mechanistically distinct from transmitter release at axon terminals utilizing amino acid neurotransmitters.

Antidepressant-binding sites in brain and platelets

[3H]Imipramine and [3H]paroxetine label with high affinity a site associated with the serotonin transporter in brain and platelets. The maximum binding capacity (Bmax) of [3H]imipramine in platelets is reduced in untreated depressed patients, and it may represent a useful biological marker in depression. The existence of an endogenous ligand acting on the [3H]imipramine-recognition site to modulate the serotonin transporter has been proposed by several laboratories. 5-Methoxytryptoline inhibits [3H]imipramine binding and [3H]serotonin uptake in the nanomolar range. This compound has been reported to occur in the pineal gland, but probably only in trace amounts. While the physiological relevance of 5-methoxytryptoline or a close analogue remains an open question, the possibility exists that the 'endocoid' for the [3H]imipramine-recognition site plays a role in the pathogenesis of depression.

Cyclooxygenase polymorphisms and risk of cardiovascular events: the Atherosclerosis Risk in Communities (ARIC) study

Cyclooxygenase-derived prostaglandins modulate cardiovascular disease risk. We genotyped 2212 Atherosclerosis Risk in Communities study participants (1,023 incident coronary heart disease (CHD) cases; 270 incident ischemic stroke cases; 919 non-cases) with available DNA for polymorphisms in PTGS1 and PTGS2. Using a case-cohort design, associations between genotype and CHD or stroke risk were evaluated using proportional hazards regression. In Caucasians, the reduced function PTGS1 -1006A variant allele was significantly more common among stroke cases compared to non-cases (18.2 versus 10.6%, P=0.027). In African Americans, the reduced function PTGS2 -765C variant allele was significantly more common in stroke cases (61.4 versus 49.4%, P=0.032). No significant relationships with CHD risk were observed. However, aspirin utilization appeared to modify the relationship between the PTGS2 G-765C polymorphism and CHD risk (interaction P=0.072). These findings suggest that genetic variation in PTGS1 and PTGS2 may be important risk factors for the development of cardiovascular disease events. Confirmation in independent populations is necessary.

Pallidal control of substantia nigra dopaminergic neuron firing pattern and its relation to extracellular neostriatal dopamine levels

The firing patterns of dopaminergic neurons in vivo are strongly modulated by afferent input. The principal GABAergic inputs to the dopaminergic neurons of the substantia nigra originate from neurons of the neostriatum, globus pallidus and substantia nigra pars reticulata. It has previously been shown that the firing pattern of nigral dopaminergic neurons can be manipulated by pharmacologically induced excitation or inhibition of the globus pallidus with relatively little effect on firing rate. We used this technique to explore the relation between the firing pattern of dopaminergic neurons and extracellular dopamine levels in the neostriatum in vivo. Specifically, we tested whether an increase in burst firing in dopaminergic neurons produced by increased pallidal activity led to increased extracellular dopamine levels in the neostriatum. Single unit extracellular recording combined with simultaneous microdialysis was used to measure the firing rates and patterns of dopaminergic neurons and extracellular striatal dopamine levels, respectively, during bicuculline-induced excitation of the globus pallidus. Pallidal excitation resulted in a marked increase in burst firing in dopaminergic neurons along with only a slight increase in firing rate, but produced a significant elevation (approximately 45%) in neostriatal dopamine levels. These data suggest that afferent-induced burst firing in dopaminergic neurons leads to an increase in extracellular dopamine levels in the neostriatum when compared with less bursty patterns with similar overall firing rates.

CYP2C9 genotype as a predictor of drug disposition in humans

Discovery of genetic polymorphisms in CYP2C9 has stimulated numerous in vitro and in vivo studies evaluating the influence of CYP2C9 genotype on metabolic activity and drug disposition. CYP2C9*2 (Arg144Cys) and *3 (Ile359Leu) have been the most widely studied alleles. They are present in approximately 10-15% and 5-10% of white populations, respectively, and are even less frequent in black and Asian populations. The CYP2C9*2 and *3 alleles have been consistently associated with lower intrinsic clearance compared with CYP2C9*1 in vitro; however, the magnitude of these differences appears to be highly substrate-specific. In addition, multiple human studies have demonstrated significant associations between CYP2C9 genotype and the disposition of substrates such as warfarin, phenytoin and various sulfonylureas, angiotensin II receptor blockers and non-steroidal antiinflammatory agents. Individuals carrying the CYP2C9*2 and *3 alleles also have lower warfarin and phenytoin daily dose requirements, and appear more susceptible to adverse events during the initiation of therapy. Collectively, these findings suggest that CYP2C9 genotype-guided dosing may be clinically useful and warrants prospective investigation.

Biosynthetic response of passaged chondrocytes in a type II collagen scaffold to mechanical compression

To investigate the potential utility of mechanical loading in articular cartilage tissue engineering, porous type II collagen scaffolds seeded with adult canine passaged chondrocytes were subjected to static and dynamic compressions of varying magnitudes (0-50% static strain) and durations (1-24 h), and at different times during culture (2-30 days postseeding). The effects of mechanical compression on the biosynthetic activity of the chondrocytes were evaluated by measuring the amount of (3)H-proline-labeled proteins and (35)S-sulfate-labeled proteoglycans that accumulated in the cell-scaffold construct and was released to the medium during the loading period. Similar to published results on loading of articular cartilage explants, static compression decreased protein and proteoglycan biosynthesis in a time- and dose-dependent manner (each p < 0.005), and selected dynamic compression protocols were able to increase rates of biosynthesis (p < 0.05). The main difference between the results seen for this tissue engineering system and cartilage explants was in the amount of newly synthesized matrix molecules that accumulated within the construct under dynamic loading, with less accumulating in the type II collagen scaffold. In summary, the general biosynthetic response of passaged chondrocytes in the porous type II collagen scaffolds is similar to that seen for chondrocytes in their native environment. Future work needs to be directed to modifications of the cell-seeded construct to allow for the capture of the newly synthesized matrix molecules by the scaffold.

Effects of a cultured autologous chondrocyte-seeded type II collagen scaffold on the healing of a chondral defect in a canine model

Using a previously established canine model for repair of articular cartilage defects, this study evaluated the 15-week healing of chondral defects (i.e., to the tidemark) implanted with an autologous articular chondrocyte-seeded type II collagen scaffold that had been cultured in vitro for four weeks prior to implantation. The amount and composition of the reparative tissue were compared to results from our prior studies using the same animal model in which the following groups were analyzed: defects implanted with autologous chondrocyte-seeded collagen scaffolds that had been cultured in vitro for approximately 12 h prior to implantation, defects implanted with autologous chondrocytes alone, and untreated defects. Chondrocytes, isolated from articular cartilage harvested from the left knee joint of six adult canines, were expanded in number in monolayer for three weeks, seeded into porous type II collagen scaffolds, cultured for an additional four weeks in vitro and then implanted into chondral defects in the trochlear groove of the right knee joints. The percentages of specific tissue types filling the defects were evaluated histomorphometrically and certain mechanical properties of the repair tissue were determined. The reparative tissue filled 88+/-6% (mean+/-SEM; range 70-100%) of the cross-sectional area of the original defect, with hyaline cartilage accounting for 42+/-10% (range 7-67%) of defect area. These values were greater than those reported previously for untreated defects and defects implanted with a type II collagen scaffold seeded with autologous chondrocytes within 12 h prior to implantation. Most striking, was the decreased amount of fibrous tissue filling the defects in the current study, 5+/-5% (range 0-26%) as compared to previous treatments. Despite this improvement, indentation testing of the repair tissue formed in this study revealed that the compressive stiffness of the repair tissue was well below (20-fold lower stiffness) that of native articular cartilage.

Modulation of the contractile and biosynthetic activity of chondrocytes seeded in collagen-glycosaminoglycan matrices

Studies have demonstrated that articular chondrocytes can express the gene for alpha-smooth muscle actin (SMA) and can contract porous polymeric matrices employed for tissue engineering, thereby altering the pore structure and distorting the shape of the scaffold. The objectives of this study were to determine whether an agent known to disrupt microfilament organization in chondrocytes could reduce this contractility and to assess whether there was an association between the contractile behavior of chondrocytes and their biosynthetic activity. Staurosporine, an antibiotic known to inhibit protein kinase C and disrupt cytoskeletal structure, was used as the agent to modulate the chondrocytic phenotype and contractile and biosynthetic activity of serially passaged adult canine chondrocytes seeded in type 1 collagen-glycosaminoglycan scaffolds. Cells in monolayer culture treated with as little as 3 nM staurosporine for 4 days contained type II procollagen, whereas few cells in the untreated control cultures demonstrated type II procollagen synthesis. Treatment with staurosporine also led to a decrease in the amount of SMA synthesized by the cells. Consistent with this decreased expression of the contractile actin isoform, cells cultured in the collagen-glycosaminoglycan scaffolds and treated with 5 nM staurosporine contracted the scaffold significantly less than untreated cells (15% diameter contraction by treated cells, compared with more than 50% contraction by untreated cells). The staurosporine-treated cells were biosynthetically active, displaying higher rates of protein and glycosaminoglycan synthesis, as indicated by rates of incorporation of [(3)H]proline and [(35)S]sulfate, respectively, compared with untreated cells. The long-held notion that changes in cytoskeletal structure influence phenotypic characteristics of cultured chondrocytes may now be extended to relate expression of a specific muscle actin isoform to certain cell processes. Moreover, the finding that chondrocytes with a lower level of expression of SMA and reduced contractility display higher rates of biosynthesis warrants further study.

Delivery of plasmid DNA to articular chondrocytes via novel collagen-glycosaminoglycan matrices

Our primary objective was to fabricate a porous gene-supplemented collagen-glycosaminoglycan (GSCG) matrix for sustained delivery (over a period of several weeks) of plasmid DNA to articular chondrocytes when implanted into cartilage lesions. The specific aims of this in vitro study were to determine the release kinetics profiles of plasmid DNA from the GSCG matrices, and to determine the ability of the released plasmid DNA to transfect adult canine articular chondrocytes. In particular, we evaluated the effects of two variables, cross-linking treatment and the pH at which the DNA was incorporated into the matrices, on the amount of the plasmid DNA that remained bound to the GSCG matrices after passive (nonenzymatic) leaching and on the expression of a reporter gene in articular chondrocytes grown in the GSCG matrices. Collagen-glycosaminoglycan matrices were synthesized without cross-linking, and by three cross-linking treatments: dehydrothermal (DHT) treatment, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) treatment, and exposure to ultraviolet (UV) radiation. The plasmid DNA was incorporated into the collagen-glycosaminoglycan matrices in solutions at pH 2.5 or 7.5. Transmission electron microscopy studies revealed plasmid DNA bound to the walls of the porous GSCG matrices. In general, the GSCG matrices fabricated at pH 2.5 retained a larger fraction of the initial DNA load after 28 days of incubation in Tris-EDTA buffer. The passive, solvent-mediated release of the plasmid DNA from the GSCG matrices showed a biphasic pattern consisting of a faster, early release rate over the initial 8 hr of leaching followed by a slower, late release rate that was relatively constant over the subsequent 28 days of leaching. Electrophoretic analyses revealed that the plasmid DNA released from the GSCG matrices fabricated at pH 2.5 had been linearized and/or degraded; whereas the plasmid DNA leached from the GSCG matrices prepared with a DNA solution at pH 7.5 was primarily supercoiled and linear. Plasmid DNA released from all GSCG matrix formulations was able to generate luciferase reporter gene expression in monolayer-cultured chondrocytes transfected with the aid of a commercial lipid reagent, and in chondrocytes cultured in the GSCG matrices without the aid of a supplemental transfection reagent. Luciferase expression in chondrocyte-seeded GSCG constructs was evident throughout the culture period (28 days), with the EDC and UV cross-linked matrices prepared at pH 7.5 providing the highest transgene expression levels. We conclude that released plasmid DNA continually transfected canine articular chondrocytes seeded into GSCG matrices in vitro for a 4-week period as evidenced by luciferase reporter gene expression. Thus, GSCG matrices can be fabricated to provide sustained release of plasmid DNA carrying a potential therapeutic gene.

Dopamine transporter density is decreased in parkinsonian patients with a history of manganese exposure: what does it mean?

Manganese (Mn) exposure can cause parkinsonism. Pathological changes occur mostly in the pallidum and striatum. Two patients with a long history of occupational Mn exposure presented with Mn-induced parkinsonism. In one patient, magnetic resonance imaging (MRI) showed findings consistent with Mn exposure, and Mn concentration was increased in the blood and urine. However, this patient's clinical features were typical of idiopathic Parkinson disease (PD). Previous pathological and positron emission tomography studies indicate that striatal dopamine transporter density is normal in Mn-induced parkinsonism, whereas it is decreased in PD. Therefore, we performed [(123)I]-(1r)-2 beta-carboxymethoxy-3beta-(4-iodophenyl)tropane ([(123)I]-beta-CIT) single-photon emission computed tomography. Severe reduction of striatal beta-CIT binding was indicated, which is consistent with PD. We propose three interpretations: (1) the patients have PD, and Mn exposure is incidental; (2) Mn induces selective degeneration of presynaptic dopaminergic nerve terminals, thereby causing parkinsonism; or (3) Mn exposure acts as a risk of PD in these patients. Our results and careful review of previous studies indicate that the axiom that Mn causes parkinsonism by pallidal lesion may be over-simplified; Mn exposure and parkinsonism may be more complex than previously thought. Further studies are required to elucidate the relationship between Mn and various forms of parkinsonism.

The effects of cross-linking of collagen-glycosaminoglycan scaffolds on compressive stiffness, chondrocyte-mediated contraction, proliferation and biosynthesis

The healing of articular cartilage defects may be improved by the use of implantable three-dimensional matrices. The present study investigated the effects of four cross-linking methods on the compressive stiffness of collagen-glycosaminoglycan (CG) matrices and the interaction between adult canine articular chondrocytes and the matrix: dehydrothermal treatment (DHT), ultraviolet irradiation (UV), glutaraldehyde treatment (GTA), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC). The degree and kinetics of chondrocyte-mediated contraction, chondrocyte proliferation, and protein and glycosaminoglycan synthesis were evaluated over a four-week period in vitro. Cell-mediated contraction of the matrices varied with cross-linking: the most compliant DHT and UV matrices contracted the most (60% reduction in matrix diameter) and stiffest EDAC matrices contracted the least (30% reduction in matrix diameter). All cross-linking protocols permitted cell proliferation and matrix synthesis as measured by DNA content and radiolabeled sulfate and proline incorporation, respectively. During the first week in culture, a lower level of proliferation was seen in the GTA matrices but over the four-week culture period, the GTA and EDAC matrices provided for the greatest cell proliferation. On day 2, there was a significantly lower rate of 3H-proline incorporation in the GTA matrices (p<0.003) although at later time points, the EDAC and GTA matrices exhibited the highest levels of matrix synthesis. With regard to cartilage-specific matrix molecule synthesis, immunohistochemistry revealed a greater amount of type II collagen in DHT and UV matrices at the early time points. These findings serve as a foundation for future studies of tissue engineering of articular cartilage and the association of chondrocyte contraction and the processes of mitosis and biosynthesis.

Difficulties in anticoagulation management during coadministration of warfarin and rifampin

The clinical significance of rifampin's induction of warfarin metabolism is well documented, but no published studies or case reports have quantified this interaction with respect to the international normalized ratio (INR). A patient receiving concomitant rifampin and warfarin to treat a mycobacterial infection and intraventricular thrombus, respectively, underwent routine INR testing at a pharmacist-managed anticoagulation clinic to assess his anticoagulation regimen. A 233% increase in warfarin dosage over 4 months proved insufficient to attain a therapeutic INR during long-term rifampin therapy More aggressive titration of the warfarin dosage was needed. In addition, a gradual 70% reduction in warfarin dosage over 4-5 weeks was necessary to maintain a therapeutic INR after rifampin discontinuation, demonstrating the clinically significant offset of this drug interaction. Extensive changes in warfarin dosage are required to attain and maintain a therapeutic INR during the initiation, maintenance, and discontinuation of rifampin.

Colonoscopic findings in intestinal Behçet's disease

The aims of this study were to investigate the clinical and colonoscopic characteristics of patients with intestinal Behçet's disease and to compare the findings of typical and atypical intestinal Behçet's disease. Ninety-four patients diagnosed as having intestinal Behçet's disease were included. Of these, we considered 42 patients as having complete or incomplete type; these fulfilled the international criteria as "typical," and the other 52 patients were classified as having "atypical" intestinal Behçet's disease. Abdominal pain was the most common symptom (92%), followed by diarrhea and gastrointestinal bleeding. All of the 22 patients with a history of surgery had ulcers at the anastomotic site. Most of the patients, who had never been operated on, had lesions in the ileocecal area (96%). Sixty-three patients (67%) had a single ulcer. Many (76%) of the ulcers were larger than 1 cm, and the mean size of the ulcers was 2.9 cm. Most (99%) of the ulcers were round/oval or geographic in shape. Usually ulcers were deep (62%), and their margins discrete (80%). There was no difference in the endoscopic findings of typical and atypical intestinal Behçet's disease. Typical colonoscopic findings in intestinal Behçet's disease were single or a few deep ulcers with discrete margins in the ileocecal area or anastomotic site. Endoscopic characteristics of patients with intestinal involvement in the case of "suspect" or "possible" type of Behçet's disease that lack the systemic manifestations of Behçet's disease were in accord with those in "complete" or "incomplete" types of Behçet's disease, who fulfill the International Study Group for Behçet's Disease criteria.

Articular cartilage chondrocytes in type I and type II collagen-GAG matrices exhibit contractile behavior in vitro

Natural healing of articular cartilage defects generally does not occur, and untreated lesions may predispose the joint to osteoarthritis. To promote healing of cartilage defects, many researchers are turning toward a tissue engineering approach involving cultured cells and/or porous, resorbable matrices. This study investigated the contractile behavior of cultured canine chondrocytes seeded in a porous collagen-glycosaminoglycan (GAG) scaffold. Chondrocytes isolated from the knee joints of adult canines and expanded in monolayer culture were seeded into porous collagen-GAG scaffolds. Scaffolds were of two different compositions, with the predominant collagen being either type I or type II collagen, and of varying pore diameters. Over the 4-week culture period, the seeded cells contracted all of the type I and type II collagen-based matrices, despite a wide range of stiffness (145 +/- 23 Pa, for the type I scaffold, to 732 +/- 35 Pa, for the type II material). Pore diameter (25-85 microm, type I; and 53-257 microm, type II) did not affect cell-mediated contraction. Immunohistochemical staining revealed the presence of alpha-smooth muscle actin, an isoform responsible for contraction of smooth muscle cells and myofibroblasts, in the cytoplasm of the seeded cells and in chondrocytes in normal adult canine articular cartilage.

Outgrowth of chondrocytes from human articular cartilage explants and expression of alpha-smooth muscle actin

The objectives of this study were to investigate the effect of various enzymatic treatments on the outgrowth of chondrocytes from explants of adult human articular cartilage and the expression of a specific contractile protein isoform, alpha-smooth muscle actin, known to facilitate wound closure in other connective tissues. Explants of articular cartilage were prepared from specimens obtained from patients undergoing total joint arthroplasty. The time to cell outgrowth in vitro was determined and the expression of alpha-smooth muscle actin shown by immunohistochemistry. Treatment of the explants with collagenase for 15 minutes reduced the time to outgrowth from more than 30 days to 3 days. Hyaluronidase, chondroitinase ABC, and trypsin applied for the 15-minute period had no effect on the time to cell outgrowth when compared with untreated controls. Pretreatment with hyaluronidase prior to collagenase reduced the time to outgrowth. A notable finding of this study was that the majority of chondrocytes in the adult human articular cartilage specimens and virtually all of the outgrowing cells contained alpha-smooth muscle actin. We conclude that human articular chondrocytes have the capability to migrate through enzymatically degraded matrix and express a contractile actin isoform. Collagenase treatment reduces the time required for cell outgrowth.

Effects of harvest and selected cartilage repair procedures on the physical and biochemical properties of articular cartilage in the canine knee

This study utilizes a canine model to quantify changes in articular cartilage 15-18 weeks after a knee joint is subjected to surgical treatment of isolated chondral defects. Clinical and experimental treatment of articular cartilage defects may include implantation of matrix materials or cells, or both. Three cartilage repair methods were evaluated: microfracture, microfracture and implantation of a type-II collagen matrix, and implantation of an autologous chondrocyte-seeded collagen matrix. The properties of articular cartilage in other knee joints subjected to harvest of articular cartilage from the trochlear ridge (to obtain cells for the cell-seeded procedure) were also evaluated. Physical properties (thickness, equilibrium compressive modulus, dynamic compressive stiffness, and streaming potential) and biochemical composition (hydration, glycosaminoglycan content, and DNA content) of the cartilage from sites distant to the surgical treatment were compared with values measured for site-matched controls in untreated knee joints. No significant differences were seen in joints subjected to any of the three cartilage repair procedures. However, a number of changes were induced by the harvest operation. The largest changes (displaying up to 3-fold increases) were seen in dynamic stiffness and streaming potential of patellar groove cartilage from joints subjected to the harvest procedure. Whether the changes reported will lead to osteoarthritic degeneration is unknown, but this study provides evidence that the harvest procedure associated with autologous cell transplantation for treatment of chondral defects may result in changes in the articular cartilage in the joint.

Dynamical studies of gratings formed in polymer-dispersed liquid crystal films doped with a guest-host dye

This study investigated the dynamic behavior of the first-order diffraction efficiency of gratings formed in polymer-dispersed liquid crystal (PDLC) films doped with a guest-host dye. PDLC films were fabricated using various LC-polymer mixing ratios, and written with various powers. Experimental results indicated that several peaks appeared in the curve of the first-order diffraction efficiency versus time. According to the light scattering study, we believe that the first peak was due to the superposition of density and absorption gratings. The density grating was associated with the spatially varied molecular weight of polymer molecules across the sample, and the absorption grating resulted from the spatially varied density of free electrons. The other peaks were caused by the superposition of the absorption and phase gratings. The phase grating was generated by the formation of a periodic structure of polymer-rich and LC-rich regions in the sample. This study also proposes a model to explain these experimental results. Moreover, the theory derived from this model correlates well with the experimental results, allowing us to determine the amplitude of the final grating.

Determination of N,N-dimethylaminoethyl chloride and the dimethylaziridinium ion at sub-ppm levels in diltiazem hydrochloride by LC-MS with electrospray ionisation

An LC-MS method is described for the determination of the synthetic reagent N,N-dimethylaminoethyl chloride (DMC) in the drug substance diltiazem hydrochloride, for which the permissible limit is not more than 1 ppm (microgram g-1). The N,N-dimethylaziridinium ion (DMA), the reactive intermediate formed by cyclisation of DMC, is also detected. A column switching arrangement is used: diltiazem hydrochloride is trapped on a reversed-phase HPLC column, and the polar analytes are separated by ion exchange chromatography. Ionisation is effected by positive-ion electrospray, and the quadrupole filter mass spectrometer is operated in the selected ion recording mode. The detection limit (peak height-to-baseline noise ratio = 3) for DMC varies from day to day in the range < 0.05 to 0.1 ppm. The response for DMC is linear (r > 0.999) over the concentration range 0.2-10 ppm, and the repeatability is better than 7% (relative standard deviation) at 1.0 ppm. Concentrations of DMC in diltiazem hydrochloride from the manufacturing facility under study ranged from undetectable to about 0.07 ppm. An indirect TLC method has been published for the determination of DMC in mepyramine maleate, but it lacks the necessary sensitivity and specificity. The LC-MS method presented is direct, straightforward and suitable for routine use.

Mechanisms involved in the antiplatelet activity of Staphylococcus aureus lipoteichoic acid in human platelets

In this study, gram-positive Staphylococcus aureus lipoteichoic acid (LTA) dose-dependently (0.1-1.0 microg/ml) and time-dependently (10-60 min) inhibited platelet aggregation in human platelets stimulated by agonists. LTA also dose-dependently inhibited phosphoinositide breakdown and intracellular Ca+2 mobilization in human platelets stimulated by collagen. LTA (0.5 and 1.0 microg/ml) also significantly inhibited thromboxane A2 formation stimulated by collagen in human platelets. Moreover, LTA (0.1-1.0 microg/ml) dose-dependently decreased the fluorescence of platelet membranes tagged with diphenylhexatrience. Rapid phosphorylation of a platelet protein of Mr. 47,000 (P47), a marker of protein kinase C activation, was triggered by PDBu (30 nM). This phosphorylation was markedly inhibited by LTA (0.5 and 1.0 microg/ml) within a 10-min incubation period. These results indicate that the antiplatelet activity of LTA may be involved in the following pathways: LTA's effects may initially be due to induction of conformational changes in the platelet membrane, leading to a change in the activity of phospholipase C, and subsequent inhibition of phosphoinositide breakdown and thromboxane A2 formation, thereby leading to inhibition of both intracellular Ca+2 mobilization and phosphorylation of P47 protein. Therefore, LTA-mediated alteration of platelet function may contribute to bleeding diathesis in gram-positive septicemic and endotoxemic patients.

Artefact formation in the determination of residual solvents according to a method of the European Pharmacopeia

Method 2 of the procedure for the identification and assay of residual solvents, of the European Pharmacopeia 3rd edition 1999 addendum, leads to artefactual formation of N-chlorodimethylamine when the hydrochlorides of basic compounds are examined. This is due to degradation of the dissolution solvent N,N-dimethylformamide under the prescribed conditions. N-Chlorodimethylamine has been detected during analysis of several hydrochloride salts of nitrogen bases including drug substances. Artefact formation did not occur consistently with all the compounds examined, but with diltiazem hydrochloride it was observed in the majority of experiments. The discovery that the alkylating reagent N,N-dimethylaminoethyl chloride (DMC) used in the synthesis of diltiazem gives apparently high yields of N-chlorodimethylamine was cause for concern. However, it has been confirmed that production batches of diltiazem hydrochloride contain <1 ppm of this synthetic intermediate. The formation of N-chlorodimethylamine in the presence of the drug substance is probably due to a reaction between dimethylformamide and HCl, that would be released as a result of hydrolysis by residual water of the O-acetyl function of diltiazem. In view of these findings, the compendial general method should be reviewed. It may be necessary to adopt a different approach to the drafting of methods for volatile impurities, since most of the operating conditions are in practice specific to the substance being examined.

Comparison of the relative activities of alpha-tocopherol and PMC on platelet aggregation and antioxidative activity

In this study, PMC (2,2,5,7,8-pentamethyl-6-hydroxychromane), a potent antioxidant derived from alpha-tocopherol, dose-dependently inhibited agonist-induced platelet aggregation in human platelet-rich plasma. PMC is over 5-10 times more potent than alpha-tocopherol in inhibiting human platelet aggregation. Moreover, PMC (25-350 microM) dose-dependently reduced the relative fluorescence intensity of platelet membrane tagged with diphenylhexatriene (DPH). PMC is about 6-times more potent than alpha-tocopherol on this effect. Furthermore, antioxidative activity of PMC was investigated using two in vitro models. PMC inhibited non-enzymatic iron-induced lipid peroxidation in rat brain homogenates with an IC50 value of 0.21+/-0.05 microM. It was more potent than alpha-tocopherol or other classical antioxidants. PMC also scavenged the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). The concentration of PMC resulting in a decrease of 0.20 in the absorbance of DPPH was about 12.1+/-3.6 microM, was comparable in potency to alpha-tocopherol, butylated hydroxytoluence and Trolox. The antiplatelet activity of PMC may possibly be due initially to an increase in fluidity of the platelet membrane followed by inhibition of platelet aggregation. Our results indicate that PMC is a potentially effective antioxidant and antiaggregating agent, and could be helpful the design of compounds with more clinical effectiveness.

Evaluation of exposure to ethylene glycol monoethyl ether acetates and their possible haematological effects on shipyard painters

OBJECTIVES

To evaluate exposure to mixed solvents containing ethylene glycol monoethyl ether acetate (EGEEA) in shipyard painters, to determine if EGEEA is toxic to the bone marrow.

METHODS

An industrial hygiene survey was performed to identify exposure to EGEEA of two groups of shipyard painters, a low exposure group (n = 30) and a high exposure group (n = 27). Urinary ethoxyacetic acid and methyl hippuric acid as well as haemoglobin, packed cell volume, red cell indices, total and differential white blood cell counts (WBCs), and platelet count for the shipyard painters and the control subjects were measured.

RESULTS

The mean (range) exposure concentration (ppm) to EGEEA in the high and low exposure groups were 3.03 (not detectable to 18.27), 1.76 (not detectable to 8.12), respectively. The concentrations of methyl hippuric acid and ethoxyacetic acid in the high exposure group were significantly higher than those in the control group. The mean WBCs in the high exposure group were significantly lower than in the control group, and a significant proportion, six (11%) of the 57 painters, were leucopenic; none of the controls were affected.

CONCLUSION

The high rate of possible haematological effects among shipyard painters and a hygienic evaluation of their working environment in the present study suggests that EGEEA might be toxic to bone marrow.

Determinants of the center of mass trajectory in human walking and running

Walking is often modeled as an inverted pendulum system in which the center of mass vaults over the rigid stance limb. Running is modeled as a simple spring-mass system in which the center of mass bounces along on the compliant stance limb. In these models, differences in stance-limb behavior lead to nearly opposite patterns of vertical movements of the center of mass in the two gaits. Our goal was to quantify the importance of stance-limb behavior and other factors in determining the trajectory of the center of mass during walking and running. We collected kinematic and force platform data during human walking and running. Virtual stance-limb compression (i.e. reduction in the distance between the point of foot-ground contact and the center of mass during the first half of the stance phase) was only 26% lower for walking (0.091 m) than for running (0.123 m) at speeds near the gait transition speed. In spite of this relatively small difference, the center of mass moved upwards by 0.031 m during the first half of the stance phase during walking and moved downwards by 0.073 m during the first half of the stance phase during running. The most important reason for this difference was that the stance limb swept through a larger angle during walking (30.4 degrees) than during running (19.2 degrees). We conclude that stance-limb touchdown angle and virtual stance-limb compression both play important roles in determining the trajectory of the center of mass and whether a gait is a walk or a run.

In vivo gene transfer methods in the bladder without viral vectors

OBJECTIVE

To examine three in vivo gene transfer methods, without viral vectors, for use in bladder cancer.

MATERIALS AND METHODS

Three methods were selected: (i) haemagglutinating virus of Japan (HVJ)-liposomes possessing membrane fusion activity were intraluminally injected into rat bladders; (ii) using a particle gun, rabbit bladder mucosa was bombarded with DNA-coated gold microcarriers; (iii) electrotransfection was also assessed in rabbit bladder by pulsed direct currents (0.15-0.2 A, 50 ms, repeated eight times) generated between needle electrodes after the submucosal injection of DNA solution. The beta-galactosidase gene and chloramphenicol acetyl-transferase gene were used as marker genes to detect gene transfer.

RESULTS

HVJ liposomes efficiently transfected superficial layers of urothelium, with a peak of expression on day 5. The particle gun produced a heterogeneous but efficient transfection in deeper layers of the urothelium. By electrotransfection, both submucosal interstitial cells and urothelium were transfected. No major complications occurred with these three methods.

CONCLUSION

HVJ-liposomes are potentially useful for treating carcinoma in situ. With further refinement, the last two methods may be suitable for adjuvant therapy in treating localized bladder tumours.

Ketoacidosis with hyperglycemia in heavy drinkers: a report of 12 cases

BACKGROUND

Heavy alcohol intake (> 45 g daily) might be a cause of diabetes. The short-term risks of heavy alcohol intake include ketoacidosis, glucose intolerance and pancreatitis. Alcoholic ketoacidosis (AKA) in combination with hyperglycemia mimics diabetic ketoacidosis (DKA). We described the characteristics of heavy drinkers with ketoacidosis and hyperglycemia but without a prior history of diabetes.

METHODS

Twelve habitually heavy drinkers who had not been previously diagnosed as diabetes were identified by reviewing the records of diabetic patients admitted to Chang Gung Memorial Hospital from 1989 to 1992. All of them met DKA criteria.

RESULTS

Elevated glycohemoglobulin (HbAlc) level is an indicator for the diagnosis of diabetes. Among these 12 patients, 10 had elevated levels of HbAlc and 2 had normal HbAlc levels. Of these 2 patients, 1 had an elevated level of HbAlc 6 months later; the other who was a female who after observation, had normal levels of HbAlc and glucose for the follow-up of two years.

CONCLUSION

We found that most heavy drinkers with both ketoacidosis and hyperglycemia also had diabetes as indicated by high levels of HbAlc. The only female patient had normal HbAlc and was diagnosed as AKA rather than DKA.

Defining drug purity through chromatographic and related methods: current status and perspectives

Chromatographic and electrophoretic techniques play a preeminent role in assessing the quality of drug substances and drug products. Current ICH guidelines place in a legal framework what has been common practice in modern pharmaceutical research and quality control. This paper reviews some aspects of current requirements for evaluating the purity of chemically synthesized new drug substances and drug products, and suggests some possible future trends.

Studies on the synthesis and structure-activity relationships of 2-(2-functionalized pyrrolidin-4-ylthio)-1 beta-methylcarbapenems

A series of new carbapenem derivatives, which have a pyrrolidin-4-ylthio group substituted with a hydroxyalkyl or carbamoyl group at the 2' position as the C-2 side chain, have been prepared. The antibacterial activity and the stability to renal dehydropeptidase-I of these compounds were investigated, and the structure-activity relationships were studied. Among these new carbapenems, (1R,5S,6S)-2-[(2S,4S)-2-¿(2-hydroxy)ethylmercaptomethyl¿pyrroli din-4 -ylthio]-6-[(1R)-I-hydroxyethyl]-1-methyl-1-carbapen-2-em-3- carboxylic acid (1a) showed the most potent and well balanced activity and was selected as a candidate for further evaluation.

A new video path analyzer to monitor travel distance, rearing, and stereotypic movement of rats

A new video path analyzer, described herein, monitors travel distance, rearing, stereotypic movement, rotation, and speed of rats simultaneously. The video path analyzer was equipped with a cage (black background, 50 cm long x 50 cm wide x 50 cm high), camera, television screen, computer, and printer. A detailed description of this equipment is included. While studying the known activating effects of d-amphetamine on rats' behavior, we also evaluated the equipment for its maximum and accurate contribution to this study. Results indicate that this equipment compared to photocell equipment produced reliable data and offered the advantages of lower cost. It is expected to gain more popularity in the near future.

Altretamine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in cancer chemotherapy

Altretamine (hexamethylmelamine) is a cytotoxic antineoplastic agent which appears to require metabolic activation. Metabolic intermediates may act as alkylating agents; however, altretamine is not directly cross-resistant with classical alkylating agents. Objective response rates to orally administered altretamine as salvage therapy in patients with advanced ovarian cancer were 0 to 33%, with disease stabilisation in a further 8 to 78% of patients. Response rates appear to be higher in patients who have responded to previous alkylating agent or cisplatin-based therapy. There is some evidence that addition of altretamine to platinum-based combination regimens used for induction therapy of advanced ovarian cancer may improve long term survival, particularly in patients with limited residual disease. Although altretamine displays some activity in small cell lung cancer, it is unlikely to have any clinical role in the management of non-ovarian cancer. Altretamine appears to be relatively well tolerated, with gastrointestinal, neurological and haematological toxicities being the main dose-limiting adverse effects. However, assessment of accurate incidence rates for these effects is complicated by the use of altretamine with cisplatin. On the basis of the emerging body of clinical evidence, altretamine appears to have a limited role in the treatment of persistent or recurrent advanced ovarian cancer, primarily in patients who are potentially platinum sensitive yet intolerant of platinum analogues. Additionally, altretamine may be added to platinum-based regimens for induction therapy of advanced ovarian cancer. At the doses currently recommended, altretamine offers a reasonably well tolerated regimen that can be administered orally and is suitable for use on an outpatient basis.

Piroxicam-beta-cyclodextrin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in rheumatic diseases and pain states

Piroxicam-beta-cyclodextrin is a complex of the established nonsteroidal antiinflammatory drug (NSAID) piroxicam and an inert cyclic macromolecule, beta-cyclodextrin. In clinical trials in patients with rheumatic diseases or pain arising from other conditions, it was as effective an analgesic as standard piroxicam, and showed a faster onset of action on the first day of treatment. In short term pharmacodynamic studies in healthy volunteers, piroxicam-beta-cyclodextrin was equivalent to or tended to show less gastrointestinal mucosal toxicity than standard piroxicam, as assessed by endoscopy and faecal blood loss. However, no data are available on its comparative gastrointestinal mucosal effects from long term clinical trials using similar measures. Preliminary findings from a clinical study suggest piroxicam-beta-cyclodextrin caused fewer gastroduodenal lesions than tenoxicam. As with other NSAIDs, the majority of adverse events associated with piroxicam-beta-cyclodextrin in clinical trials were gastrointestinal in origin, with epigastric pain, heartburn and nausea the most common. Thus, piroxicam-beta-cyclodextrin is an effective agent in patients with rheumatic diseases or other pain states. When rapid analgesia is required in the initial treatment of acute pain, the faster onset of action of piroxicam-beta-cyclodextrin may be an advantage over the parent compound; however, this is unlikely to be important during long term therapy. The results of further long term trials are awaited before firm conclusions can be reached regarding the gastrointestinal tolerability of piroxicam-beta-cyclodextrin compared with that of standard piroxicam and other NSAIDs.

Filgrastim. A review of its pharmacological properties and therapeutic efficacy in neutropenia

Filgrastim, a recombinant human granulocyte colony-stimulating factor (G-CSF), has identical biological activity to that of endogenous human G-CSF, but differs in that it contains an N-terminal methionine residue and is not glycosylated. It principally stimulates activation, proliferation and differentiation of neutrophil progenitor cells and has been evaluated in the treatment of patients with various neutropenic conditions, both iatrogenic and disease-related. Two comparative studies have demonstrated that prophylactic administration of filgrastim 230 micrograms/m2/day significantly reduces the incidence, duration and severity of neutropenia in patients with previously untreated small-cell lung cancer receiving standard-dose chemotherapy with CDE (cyclophosphamide, doxorubicin plus etoposide). Concomitant with the amelioration of neutropenia, the incidence of febrile neutropenia was significantly reduced by 50% and there were 35 and 50% decreases in hospitalisation rates and intravenous antibiotic requirements. Since not all patients receiving standard-dose chemotherapy are at risk of infectious complications, prophylactic filgrastim use may be reserved for those patients who have developed febrile neutropenia during a previous cycle of the same regimen. This strategy may prove less costly, although potential savings must be weighed against a greater risk of patient morbidity and reduced quality of life. When combined with standard intravenous antibiotic therapy, filgrastim further decreases morbidity in patients with established febrile neutropenia and may have a positive impact on overall treatment costs by shortening the length of hospitalisation. Attention is focused on the use of haematopoietic growth factors to support dose-intensification of chemotherapy with a view to improving treatment outcomes in patients with chemo-responsive tumours. Filgrastim, used alone, permits modest increases in dose-intensity and/or dose-escalation of some standard-dose chemotherapy regimens. Moreover, the drug has proven useful as an adjunct to myeloablative chemotherapy followed by stem cell rescue with autologous bone marrow transplantation and/or peripheral blood progenitor cells. However, the impact of these dose-intensification approaches on survival remains to be determined in well-controlled clinical studies. Filgrastim is effective in increasing the neutrophil count and decreasing morbidity in patients with severe chronic neutropenia, including Kostmann's syndrome, and in idiopathic and cyclic neutropenia. In addition, filgrastim has accelerated neutrophil recovery in patients with idiosyncratic drug-induced agranulocytosis. Available data indicate that filgrastim is generally well tolerated. The most frequent adverse reaction is mild to moderate medullary bone pain, reported by approximately 20% of patients, although this can generally be controlled using simple analgesics without the need to discontinue treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Lacidipine. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic potential in the treatment of hypertension

Lacidipine is an orally administered calcium channel blocker of the dihydropyridine class, which shows selectivity for vascular smooth muscle over cardiac tissue and has a long duration of action. In studies using ambulatory blood pressure monitoring, lacidipine 2 to 8mg administered once daily in the morning reduced blood pressure over 24 hours, with the reductions being greater during the day than at night in some studies. 77 to 87% of patients with mild to moderate hypertension had their blood pressure controlled by treatment with lacidipine 2 to 8 mg/day for 1 to 4 months in dose-finding studies. When administered once daily, lacidipine 4 to 6 mg was equivalent in antihypertensive efficacy to hydrochlorothiazide 25 to 50 mg/day, atenolol 50 to 100 mg/day, and the prototype calcium channel blocker nifedipine 20 to 40 mg twice daily (sustained-release formulation). The adverse effects of lacidipine are those common to other dihydropyridine calcium channel blockers, and include headache, flushing, ankle oedema, dizziness and palpitations. The long term effects of lacidipine on cardiovascular morbidity and mortality, and possible additional clinical benefits in terms of its antiatherosclerotic effects, are under investigation; the outcome of these studies will be important in defining the future role of this agent in the treatment of hypertension. Thus, available evidence suggests lacidipine provides a further alternative to the dihydropyridine calcium channel blockers currently available for the treatment of essential hypertension.

Aniracetam. An overview of its pharmacodynamic and pharmacokinetic properties, and a review of its therapeutic potential in senile cognitive disorders

Aniracetam is a member of the nootropic class of drugs, which have possible cognition enhancing effects. It appears to positively modulate metabotropic glutamate receptors and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-sensitive glutamate receptors, and may facilitate cholinergic transmission, effects which are possibly related to its mechanism of action. Results from trials in elderly patients with mild to moderate cognitive impairment due to senile dementia of the Alzheimer type suggest that aniracetam may be of benefit, with further trials required to confirm its efficacy profile and to define more precisely those patients most likely to respond to treatment. Aniracetam 1500 mg/day was significantly more effective than placebo in all tests at 4 and 6 months, and in a further 6-month trial was more effective than piracetam 2400 mg/day in 8 of 18 tests. Preliminary evidence in the treatment of patients with cognitive impairment of cerebrovascular origin suggests aniracetam may also be of benefit in this condition. Whilst incidence rates of adverse effects are not yet available, data from trials suggest aniracetam is well tolerated. In particular, aniracetam does not appear to cause increases in liver enzyme levels. The evaluation of drugs for patients with senile cognitive disorders is a difficult area and therapeutic options are currently limited. Preliminary evidence of the potential benefits and good tolerability profile of aniracetam support continued evaluation of its use in patients with mild to moderate senile dementia of the Alzheimer type.

Protection by scoparone against the alterations of plasma lipoproteins, vascular morphology and vascular reactivity in hyperlipidaemic diabetic rabbit

1. The in vivo pharmacological effects of scoparone (6,7-dimethoxycoumarin) in a hyperlipidaemic diabetic rabbit model were investigated. 2. Three groups of rabbits were studied: (1) normal, (2) hyperlipidaemic and diabetic-untreated and (3) hyperlipidaemic and diabetic-scoparone treated. The hyperlipidaemic diabetic rabbits were fed with 1% cholesterol and treated with alloxan, a diabetogenic agent. The plasma levels of total cholesterol, total triglyceride, very low-density lipoprotein (VLDL) cholesterol, low density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol were markedly increased as soon as the rabbit became diabetic at the second week. Scoparone-treatment (5 mg kg-1 day-1, s.c.) significantly reduced the plasma lipid and lipoprotein cholesterol levels of the hyperlipidaemic diabetic rabbit to 73.3% of total cholesterol, 48.3% of total triglyceride, 66.0% of VLDL cholesterol, 55.7% of LDL cholesterol and 79.5% of HDL cholesterol. 3. Six weeks after cholesterol-feeding, the aortic arch and thoracic aorta were dissected for morphological and functional studies. In vascular rings from the untreated hyperlipidaemic diabetic rabbit, there was intimal thickening with accumulation of fatty streaks, foam cells and migration of smooth muscle cells to the intima. In the rabbits treated with scoparone, there were fewer pathological morphology changes found in vascular segments than in the untreated hyperlipidaemic diabetic rabbits. 4. In the vascular reactivity experiments, the phenylephrine-induced contraction and nitroprusside induced dilatation did not differ significantly among the three rabbit groups, except that the contraction was enhanced in the thoracic aorta of hyperlipidaemic diabetic rabbits either untreated or treated withscoparone, as compared to the normal group, and the sensitivity to nitroprusside was increased in the thoracic aorta of the scoparone-treated group as compared to the untreated group.5. The endothelium-dependent dilatation induced by acetylcholine was significantly attenuated in both the aortic arch and thoracic aorta from the hyperlipidaemic diabetic rabbits as compared to the normal rabbits. This attenuation was partially prevented, when scoparone (5 mg kg-1) was administered daily.6. These results suggest that scoparone protects against some alterations of plasma lipoproteins,vascular morphology and vascular reactivity in the hyperlipidaemic diabetic rabbit. These protective effects of scoparone may be partly related to its free radical scavenging property.