Prescription pattern of benzodiazepines for inpatients at a tertiary care university hospital in Pakistan

OBJECTIVE

To determine the point prevalence of benzodiazepine prescriptions for inpatients at a tertiary care university hospital in Pakistan and to correlate it with prescription patterns of various specialties, indications and demographic variables of the patients.

METHODS

This 24-hours point prevalence study was done at The Aga Khan University Hospital, Karachi. By convenient random sampling, 208 inpatients were interviewed. Patients' files were also studied to record the drugs administered. Data was entered into questionnaires and analyzed by SPSS 10.0.

RESULTS

The point prevalence of the benzodiazepines was 21.2%. It was higher among males than females and among surgical than non-surgical patients. Midazolam was the most commonly used benzodiazepine, followed by Alprazolam and Lorazepam. Pre-anesthesia and psychiatric symptoms were the two most common indications. Oral route was used in 84% patients for drug administration and mean Valium equivalent dosage was 4.86 mg/day. Mean length of prescription was 3 days. Longer duration of hospitalization was a significant predictor of the requirement of benzodiazepine prescription (p-value = 0.020).

CONCLUSION

Prescription pattern of benzodiazepines at a tertiary care university hospital is similar to that reported in the developed countries through monitoring at various levels by physicians, clinical pharmacist and nursing staff. Data regarding the prescription pattern of benzodiazepines is scarce, and it needs to be expanded to formulate clear guidelines regarding their prescription.

Angiographic severity and extent of coronary artery disease in patients with type 2 diabetes mellitus

Coronary angiographic characteristics of fifty patients with type 2 diabetes mellitus and coronary artery disease (CAD) were compared with fifty non diabetic patients with CAD. Type 2 diabetic patients undergoing clinically indicated elective coronary angiography were individually matched with fifty non diabetic coronary artery disease patients for age, sex and major risk factors. No significant difference was present between the mean age, presenting complains and other coronary risk factors between the two groups. Severity and extent of coronary artery involvement was assessed by a coronary artery score (CAS) using the segmental distribution method for coronary artery lesions and morphometric analysis of atherosclerotic lesion was done. Type 2 diabetic patients had a higher CAS (11.74+/-5.04 vs 8.72+/-4.87; P<0.001) as compared to the non-diabetic patients. Multivessel disease were more prevalent in both the groups (82% vs 68%; P>0.05) but diabetic patients had significantly higher number of triple vessel disease (58% vs. 38%; P<0.001). Normal coronary arteries and single vessel disease were more prevalent in non-diabetic patients (32% vs. 18%; P<0.05). As compared to non-diabetic group diabetic patients had a higher total number of diseased vessels (78.66% vs. 68%; P<0.01), a higher lesion per patient ratio (3.94+/-1.80 vs 3+/-1.67:P<0.001) and more proximal lesions (40.83% vs. 34.70%; P>.05) though not statistically significant. Morphometric analysis of coronary artery lesions revealed that diabetic patients had significantly higher number of multiple irregularity lesions (24.37% vs. 15.33%; P<0.01) and lesions were more obstructive (lesion involving 70-90% of coronary lumen: 70.53.% vs. 57.33%; P<0.05). Though there was no significant difference between the systolic left ventricular function between the two groups but significant higher regional wall motion abnormality was found more in diabetic patients (76%vs 62%; P<0.01). So type 2 diabetic patients had more severe and extensive atherosclerotic lesion in their coronary arteries than the matched non diabetic control on coronary angiography suggesting an independent effect of diabetic mellitus on atherosclerotic process specially in our population.

Comparison and outcome of commissurotomy by metallic valvotome and balloon commissurotomy

The purpose of this study was to compare the echocardiographic outcome of percutaneous transvenous metallic mitral commissurotomy (PMMC) and Percutaneous transvenous balloon mitral commissurotomy (PTMC). This prospective comparative study was carried out during the period of January 1999 to June 2000 in the department of Cardiology, National Institute of cardiovascular diseases (NICVD) and national heart foundation hospital, Dhaka Bangladesh. Two dimension, M-mode, spectral and colour Doppler studies were done to all patient of mitral stenosis both before and after PMMC and PTMC. The increased in mitral valve area in PMMC was statistically significant than PTMC. (P<0.047).

Cost implications of sexual dysfunction: the female picture

This study examined the clinical workload, outcome and direct costs of managing women with sexual dysfunction in an NHS clinic in the UK. A retrospective analysis of a 3-month period showed that of 47 referrals to the clinic, 38 undertook treatment. The therapists' assessments suggested that over 80% of patients improved on treatment. The average cost per patient was pound 472 (compared to pound 335 per annum for erectile dysfunction, which included physician's and drug costs). The average cost by type of practitioner was pound 278 (psychologist), pound 322 (physician), pound 532 (physician and psychologist) and pound 597 (sex therapist). Patients required between 1 and 51 treatment sessions, which were mainly restricted to psychological therapy. Female sexual dysfunction (FSD) represents a significant economic burden to the NHS. Further research on the potential role and cost effectiveness of pharmacological agents for FSD is warranted.

Coronary artery disease in young adults - angiographic profile

Angiographic profile of fifty young patients of coronary artery disease aged 40 or under were analysed and compared with those of fifty older patients. Mean age of younger and older group was 36.34 (range 28 to 40 years) and 55.28 (44-74 years) years respectively and most of the patients were male in both the group (92 Vs 94%). Older patients were more diabetes (40 Vs 24%) and hypertensive (38 Vs 60%) but the younger patients had more family history of premature coronary artery disease (50% Vs 24%). The incidence of smoking and dyslipidemia did not vary between the two groups. Older patients had more history of myocardial infarction (69 Vs 58%) but angina were more in young patients (42 Vs 31%). Coronary angiography revealed more number of multivessel disease in older patients (74 Vs 54%) but the younger patients had more normal coronary arteries and single vessel disease (46 vs 26%). Coronary athesclerosis was also extensive in older patients as revealed by the higher coronary score, more involvement of coronary segments, more number of diseased and diffusely involved coronary vessel in older patients. Older patients needed more revasalarization process (74 Vs 60%), more coronary bypass surgery (40 Vs 24%) and had more inoperable vessels (16% Vs 4%) than the younger patients. So the younger patients having less extensive coronary artery athesclerosis with better prognostic probability should be evaluated angiographically for further definitive management in the from of revascularization.

Correlation between severity of coronary artery athesclerosis and duration and severity of diabetes mellitus in type 2 diabetic patients

Hundred patients of Type 2 diabetes mellitus with coronary artery disease undergoing diagnostic coronary angiography were studied to determine the relation between the severity and duration of diabetes mellitus and the severity of coronary artery disease. A coronary scoring system using segmental distribution method was used to determine the severity of coronary artery disease and severity of diabetes was assessed by the level of fasting blood glucose within 48 hours of the procedure and also considering the types of treatment received for diabetes mellitus. No significant correlation was demonstrated between the severity of coronary artery disease and the severity (r =.089602; P>0.1) nor the duration (r =0.07865; P> 0.1) of diabetes mellitus on univariate analysis. So the Type 2 diabetic patients had an increased incidence of atherosclerosis in their coronary angiograms did not reflect an angiographically evident progressive coronary artery disease and results of this study suggest that the progress of large vessel coronary athesclerotic disease in diabetes mellitus of adult onset takes place independently of the progress of diabetes mellitus itself.

Coronary artery disease in young patients: clinical review and risk factor analysis

Fifty consecutive younger patients (< or = 40 years) with coronary artery disease, who underwent coronary angiography in National Institute of Cardiovascular Diseases were evaluated clinically and coronary risk factors were analyzed and compared with those of fifty older patients with coronary artery disease. Mean age of younger and older patients were 37.31 and 54.58 years respectively and myocardial infarction was the most common presenting complain in both the groups. Smoking and family history of premature coronary artery disease were more common in younger patients but the older patients were more diabetic and hypertensive. Central obesity and dyslipidemia did not vary between the two groups. Fifty percent of younger patients had one or two modifiable risk factors where sixty four percent of older patients had three or more modifiable risk factors. Forty four percent younger patients had hypercholesterolemia but a majority of patients had either isolated hypertriglyciredemia or decrease high density lipoprotein cholesterol or both with normal total cholesterol level but the total cholesterol and high density lipoprotein cholesterol index were more than 4.5. Younger patients had more number of normal coronary or single vessel diseases but older group had more number of triple vessel diseases. So the higher incidence of non-insulin dependent diabetes mellitus with central obesity suggesting insulin resistance along with unique profile of dyslipidemia, higher incidence of smoking and familial predisposition of premature coronary artery disease may be responsible for higher incidence of coronary artery disease at a premature younger age in this population.

Dobutamine-atropine stress echocardiography for the detection of coronary artery disease in patients with left ventricular hypertrophy. Importance of chamber size and systolic wall stress

BACKGROUND

Left ventricular hypertrophy is a heterogeneous disorder with distinct morphologies. Changes in wall thickness, left ventricular chamber diameter, and mass alter systolic wall stress of the left ventricle and may influence ischemic threshold. Thus, the goal of this study was to investigate the effect of the different patterns of left ventricular hypertrophy on the accuracy of dobutamine-atropine stress echocardiography.

METHODS AND RESULTS

Three-hundred eighty-six patients underwent multistage dobutamine-atropine stress echocardiography and diagnostic angiography. Echocardiograms were measured for mean and relative wall thicknesses, chamber size, left ventricular mass, and end-systolic wall stress. The patterns of ventricular hypertrophy were concentric hypertrophy (increased wall thickness and mass), eccentric hypertrophy (normal wall thickness and increased mass), and concentric remodeling (increased wall thickness and normal mass). The overall sensitivity, specificity, and accuracy of dobutamine-atropine stress echocardiography for the detection of coronary artery disease were 85%, 87%, and 86%, respectively. Increased left ventricular mass index alone did not affect accuracy. Sensitivity was markedly reduced (36%) only in those with concentric remodeling. The univariate predictors of false-negative studies were single-vessel left circumflex disease, increased wall thickness, small chamber size, hyperdynamic ejection fraction, and left ventricular concentric remodeling. Multivariate predictors were concentric remodeling (P<0.0001; odds ratio, 13.5), left ventricular ejection fraction >2 SD above normal (P<0.0001), and single-vessel left circumflex disease (P<0.0007; odds ratio, 7.6). Sensitivity was excellent in patients with small ventricles and normal wall thickness and in those with normal or large chambers regardless of wall thickness.

CONCLUSIONS

Dobutamine-atropine stress echocardiography is an accurate test in most patients with left ventricular hypertrophy, but it is insensitive in the small subset with concentric remodeling.

PEGylation of cytokines and other therapeutic proteins and peptides: the importance of biological optimisation of coupling techniques

Polyethylene glycol (PEG) modification, PEGylation, is a well established technique which has the capacity to solve or ameliorate many of the problems of protein and peptide pharmaceuticals. It is one of the most important of the molecule altering structural chemistry (MASC) techniques and in many settings is enabling technology. The use of PEG as a linker molecule is also beginning to make a contribution to the production of exciting new products. We have previously reviewed the marked differences between methods of PEGylation and the surprising and dramatic impact of different coupling techniques (using different activated PEGs) on factors such as retention of bioactivity, stability and immunogenicity of the resulting PEGylated proteins and peptides. Numerous factors play a part in this variation: the presence or absence of linkers between the PEG and the target molecule; the nature and stability of the bond(s) between the PEG, linker and target; the impact of PEG attachment on surface charge; the coupling conditions; and the relative toxicity of the activated polymer and/or coproduct(s). These are not, however, the only sources of qualitative differences in PEGylated products. Our own experience whilst developing a linkerless PEGylation technique (i.e. one attaching only PEG to the target molecule), which we devised to overcome all the major problems of pre-existing PEGylation techniques, was that considerable modification of the prototype method and a process of 'biological optimisation' was required to achieve good results in terms of conservation of bioactivity. Biological optimisation has not, as far as we are aware, been systematically applied by other groups working in PEGylation. It is the term we use to describe an iterative process for examining and refining all the steps in the PEGylation process, including manufacturing the activated polymer, in order to achieve the best possible conservation of bioactivity and other beneficial features of the method. The application of this biologically optimised PEGylation technique, using tresyl monomethoxy PEG (TMPEG), to a variety of target proteins reveals, as outlined in this review, an exceptional ability to conserve biological activity of the target. This, and the benefit of adding nothing other than PEG itself (which has an excellent safety record), to the protein, as well as other manufacturing and practical advantages, makes the method ideal for the modification of cytokines and other therapeutic proteins.

Polyethylene glycol modification: relevance of improved methodology to tumour targeting

Of all the polymers applied to molecule altering structural chemistry, polyethylene glycol (PEG) modification has numerous benefits and relatively few drawbacks. PEG is now increasingly being applied to the problems of tumour targeting, both in the context of the passive targeting of PEG-liposomes and in active targeting strategies using PEGylated anti-tumour antibodies. PEG can also serve as a useful linker molecule between targeting moieties and other agents, including cytotoxic or imaging agents and targeted liposomes. Despite these demonstrated benefits and the level of attention which PEGylation has received, relatively little consideration has been given to two key areas: first, the extent to which the coupling method has an impact on both the functionality of the PEG-adduct and the acquisition of beneficial properties; second, that the impact of PEGylation on biodistribution is complex, thus any attempt to optimise a PEG-peptide or PEG-liposome for a particular task must involve an examination of all the individual facets of the effects of PEGylation. Studies investigating the underlying principles of tumour targeting suggest that current views concerning the optimisation of PEGylated vehicles for tumour localisation need to be re-examined.

Determination of serum retinol by reversed-phase high-performance liquid chromatography

A rapid, sensitive and specific high-performance liquid chromatographic method was developed for the determination of serum levels of retinol in humans. A direct serum injection technique after deproteinisation was used to avoid lengthy pretreatment steps which can result in degradation of retinol during analysis. The column used was CLC-ODS, the mobile phase was acetonitrile-water and detection wavelength was 328 nm. Deterioration in column performance was not observed even after injection of 300 samples. The lower detection limit was 10 micrograms/l. On analyzing a serum pool six times, a C.V. of 0.7% was obtained. The method is quantitative, reproducible, rapid and highly accurate for routine analysis.

Quantitative analysis of polyethylene glycol (PEG) in PEG-modified proteins/cytokines by aqueous two-phase systems

Covalent attachment of poly(ethylene glycol) (PEG) to proteins produces conjugates with altered/improved physicochemical and biological properties which depend upon the number of PEG chains linked. Quantification of the attached PEG is however not a trivial issue. The partition coefficient, K, of the PEG-protein conjugate in PEG/dextran two-phase systems provides a quantitative measure for the degree of modification. A linear relationship between log K and the number of PEG chains was observed in fractionated PEG-modified-granulocyte-macrophage colony stimulating factor conjugates having 1 to 3 substitutions. Furthermore, in mixtures of PEG-bovine-serum-albumin conjugates with increasing degrees of modification, a linear relationship was found between log K and n, the average substitution. The increment in log K per PEG chain added is protein specific and this suggests that the interactions between the PEG-protein conjugate and the polymers in the phase system are more complex than just a simple affinity of the PEG for the PEG-rich top phase. Increasing the polymer concentration in the phase system produces larger increments in log K per PEG molecule attached and the proportionality between log K and number of PEG molecules is only compromised for conjugates with high degree of substitution when partitioned in biphasic systems of high concentration of polymers.

Tubulin GTP hydrolysis influences the structure, mechanical properties, and kinesin-driven transport of microtubules

Tubulin is a GTPase that hydrolyzes its bound nucleotide triphosphate after it becomes incorporated into a microtubule. The only known consequence of nucleotide hydrolysis is that it increases the dissociation rate of tubulin from the end of the microtubule by 2 orders of magnitude. In this study, we investigated whether microtubules composed of tubulin-GMPCPP (guanylyl alpha,beta-methylenediphosphate) (a very slowly hydrolyzed GTP analog) or tubulin-GDP exhibit additional structural or functional differences. We show that tubulin-GMPCPP microtubules are significantly stiffer than tubulin-GDP microtubules and have a 21% shallower protofilament twist angle. We also find that kinesin, a microtubule-based motor protein, transports tubulin-GMPCPP microtubules at approximately 30% faster rates than tubulin-GDP microtubules. These findings suggest that growing microtubule ends, which are thought to be composed of tubulin-GTP, may have different structural and mechanical properties from the remainder of the microtubule polymer.

High-resolution tracking of microtubule motility driven by a single kinesin motor

Kinesin is a microtubule-based motor protein that contains two identical force-generating subunits. The kinesin binding sites along the microtubule lie 8 nm apart (the dimension of the tubulin dimer), which implies that kinesin must translocate a minimum distance of 8 nm per hydrolysis cycle. Measurements of kinesin's microtubule-stimulated ATPase activity (approximately 20 ATP per sec) and velocity of transport (approximately 0.6 micron/sec), however, suggest that the net distance moved per ATP (approximately 30 nm) may be greater than one tubulin dimer under zero load conditions. To explore how kinesin translocates during its ATPase cycle, we constructed a microscope capable of tracking movement with 1-nm resolution at a bandwidth of 200 Hz and used this device to examine microtubule movement driven by a single kinesin motor. Regular stepwise movements were not observed in displacement traces of moving microtubules, although Brownian forces acting on elastic elements within the kinesin motor precluded detection of steps that were < 12 nm. Though individual steps of approximately 16 nm were occasionally observed, their infrequent occurrence suggests that kinesin rarely moves abruptly by distances of two or more tubulin subunits during its ATP hydrolysis cycle. Instead it is more likely that kinesin moves forward by the distance of only a single tubulin subunit under zero load conditions.

Nutritional aspects of mammary carcinogenesis: a case-control study

Dietary factors are believed to play an important role in mammary carcinogenesis. International correlations, case-control and cohort studies have associated the incidence and mortality from breast cancer with high fat consumption in the form of meat, gravy and dairy products. Most of these studies have been conducted in the developed countries. Due to paucity of data from developing countries, we conducted a case-control study to evaluate the role of nutritional factors in mammary carcinogenesis. This prospective study was conducted in the oncology clinic at a university hospital. On a detailed questionnaire, information was collected from 80 patients with histologically proven breast cancer (cases) and 80 normal healthy subjects (controls). Information was collected on several patients characteristics as well as intake of 44 different food items. Special care was taken to exclude any recent changes in diet, induced in cases since learning the diagnosis of breast cancer. Interviews were conducted by the same interviewer and lasted approximately 20 minutes. Analysis of data reveal no significant difference in patients characteristics between cases and controls. Similarly, no significant difference was found in the intake of most dietary items including meat and dairy products. However, a significant difference was observed in the consumption of fish, vegetable and fruits (P = 0.05). We conclude that our study fails to support the fat-breast cancer hypothesis. It also suggests a potential role of other dietary items such as fish, vegetables and fruits in mammary carcinogenesis.

Directional instability of microtubule transport in the presence of kinesin and dynein, two opposite polarity motor proteins

Kinesin and dynein are motor proteins that move in opposite directions along microtubules. In this study, we examine the consequences of having kinesin and dynein (ciliary outer arm or cytoplasmic) bound to glass surfaces interacting with the same microtubule in vitro. Although one might expect a balance of opposing forces to produce little or no net movement, we find instead that microtubules move unidirectionally for several microns (corresponding to hundreds of ATPase cycles by a motor) but continually switch between kinesin-directed and dynein-directed transport. The velocities in the plus-end (0.2-0.3 microns/s) and minus-end (3.5-4 microns/s) directions were approximately half those produced by kinesin (0.5 microns/s) and ciliary dynein (6.7 microns/s) alone, indicating that the motors not contributing to movement can interact with and impose a drag upon the microtubule. By comparing two dyneins with different duty ratios (percentage of time spent in a strongly bound state during the ATPase cycle) and varying the nucleotide conditions, we show that the microtubule attachment times of the two opposing motors as well as their relative numbers determine which motor predominates in this assay. Together, these findings are consistent with a model in which kinesin-induced movement of a microtubule induces a negative strain in attached dyneins which causes them to dissociate before entering a force-generating state (and vice versa); reversals in the direction of transport may require the temporary dissociation of the transporting motor from the microtubule. The bidirectional movements described here are also remarkably similar to the back-and-forth movements of chromosomes during mitosis and membrane vesicles in fibroblasts. These results suggest that the underlying mechanical properties of motor proteins, at least in part, may be responsible for reversals in microtubule-based transport observed in cells.

Polyethylene glycol (PEG) modification of granulocyte-macrophage colony stimulating factor (GM-CSF) enhances neutrophil priming activity but not colony stimulating activity

PEG-modified proteins have numerous advantages over their unmodified counterparts (increased half life, reduced antigenicity, improved solubility), but almost without exception, they show a modest to marked reduction in biological or enzymatic activity. However, while investigating a new protocol for the preparation of PEG-proteins, we compared PEG-modified and unmodified GM-CSF with respect to their polymorphonuclear neutrophil granulocyte (PMN) priming activities. PEG-GM-CSF was unexpectedly more active than GM-CSF in its ability to prime neutrophils to respond to the synthetic peptide n-formyl-methionyl-leucyl-phenylalanine (FMLP) with an oxidative burst (assessed both by nitroblue tetrazolium reduction and ferricytochrome c reduction). These results were in contrast to the findings for colony stimulating activity and with GM-CSF induced thymidine uptake, where the biological activity was unchanged or reduced. The enhanced neutrophil priming activity of PEG-GM-CSF was confirmed using FPLC fractionated PEG-modified GM-CSF. This showed changes in the bioactivity profile consistent with both the shift in protein elution profile and enhanced activity of the PEG-modified material (reflected in the increased area under the bioactivity curve). We also excluded a neutrophil priming action for PEG-modified fetal calf serum proteins, carrier proteins and 'irrelevant' cytokine, erythropoietin. The dissociation of the two bioactivities was confirmed using individual FPLC fractions. These results suggest the presence of differences in either binding, receptor/ligand processing or signal transduction for neutrophils versus progenitors, that are differentially affected by PEG-modification of GM-CSF. The demonstration that PEG-modification can partially dissociate two biological activities suggests the feasibility of using PEG-modification to produce proteins with subtly altered spectra of biological activity and hence new ranges of clinical applications.

Effect of acetazolamide on cerebral blood flow and capillary patency

This study investigated the effects 2 h after administration of acetazolamide on cerebral blood flow and the pattern of cerebral capillary perfusion. Arterial blood pressure, heart rate, arterial blood gases, and pH were recorded in two groups of rats along with either regional cerebral blood flow or the percentage of capillary volume per cubic millimeter and number per square millimeter perfused as determined in cortical, thalamic, pontine, and medullary regions of the brain. Blood pressure, heart rate, and arterial PCO2 were not significantly different between the rats receiving acetazolamide (100 mg/kg) and the controls. Arterial blood pH was significantly lower in the acetazolamide rats. Blood flow increased significantly in the cortical (+ 102%), thalamic (+ 89%), and pontine (+ 88%) regions receiving acetazolamide. In control rats, approximately 60% of the capillaries were perfused in all of the examined regions. The percentage of capillaries per square millimeter perfused was significantly greater in the cortical (+ 52%), thalamic (+ 49%), and pontine (+ 47%) regions of acetazolamide rats compared with controls. In the medulla the increases in blood flow and percentage of capillaries perfused were not significant. Thus in the regions that acetazolamide increased cerebral blood flow, it also increased the percentage of capillaries perfused.

Polyethylene glycol (PEG)-modified granulocyte-macrophage colony-stimulating factor (GM-CSF) with conserved biological activity

Polyethylene glycol (PEG) modification improves the pharmacological properties of proteins, usually extending plasma half-life and concomitantly increasing in vivo bioactivity, reducing both antigenicity and immunogenicity, and increasing solubility and resistance to proteolysis. Despite these established benefits, few PEG proteins are in use. Current coupling methods are either traumatic for the protein or involve lengthy and difficult procedures to activate monomethoxyPEG (MPEG). We have applied a new coupling method that allows coupling of MPEG directly to proteins under physiological conditions. Using this method with recombinant human (rh)granulocyte-macrophage colony-stimulating factor (GM-CSF) we were able to construct biologically active PEG-GM-CSF. Fast protein liquid chromatography (FPLC) and phase-partitioning confirmed the presence of PEG modification, and the former was used to fractionate modified and unmodified material. Bioactivity was measured in colony assays of normal human bone marrow cells and by tritiated thymidine uptake (of chronic myeloid leukemia cells and TF-1 cells). With both uptake and colony assays, using unfractionated material, we observed only a modest reduction in biological activity. Assays of FPLC-fractionated material confirmed that much of the bioactivity of the PEG-GM-CSF preparations was due to the modified species and any residual unmodified GM-CSF. Species uncontaminated by tresylmonomethoxyPEG (TMPEG; which was somewhat inhibitory in the thymidine uptake assay and eluted over a broad region of the FPLC profile) had no significant reduction in activity, but we cannot rule out the possibility that PEG-GM-CSF species eluting elsewhere in the profile had modest reduction of activity. Subcutaneous injection into mice confirmed the anticipated improved half-life in vivo and demonstrated a longer uptake from the injection site. This is, as far as we are aware, the first successful construction of PEG-GM-CSF with conserved biological activity.

Nucleotide specificity of the enzymatic and motile activities of dynein, kinesin, and heavy meromyosin

The substrate specificities of dynein, kinesin, and myosin substrate turnover activity and cytoskeletal filament-driven translocation were examined using 15 ATP analogues. The dyneins were more selective in their substrate utilization than bovine brain kinesin or muscle heavy meromyosin, and even different types of dyneins, such as 14S and 22S dynein from Tetrahymena cilia and the beta-heavy chain-containing particle from the outer-arm dynein of sea urchin flagella, could be distinguished by their substrate specificities. Although bovine brain kinesin and muscle heavy meromyosin both exhibited broad substrate specificities, kinesin-induced microtubule translocation varied over a 50-fold range in speed among the various substrates, whereas heavy meromyosin-induced actin translocation varied only by fourfold. With both kinesin and heavy meromyosin, the relative velocities of filament translocation did not correlate well with the relative filament-activated substrate turnover rates. Furthermore, some ATP analogues that did not support the filament translocation exhibited filament-activated substrate turnover rates. Filament-activated substrate turnover and power production, therefore, appear to become uncoupled with certain substrates. In conclusion, the substrate specificities and coupling to motility are distinct for different types of molecular motor proteins. Such nucleotide "fingerprints" of enzymatic activities of motor proteins may prove useful as a tool for identifying what type of motor is involved in powering a motility-related event that can be reconstituted in vitro.

Cloning and characterization of RNA polymerase core subunits of Chlamydia trachomatis by using the polymerase chain reaction

Taking advantage of sequence conservation of portions of the alpha, beta, and beta' subunits of RNA polymerase of bacteria and plant chloroplasts, we have designed degenerate oligonucleotides corresponding to these domains and used these synthetic DNA sequences as primers in a polymerase chain reaction to amplify DNA sequences from the chlamydial genome. The polymerase chain reaction products were used as a probe to recover the genomic fragments encoding the beta subunit and the 5' portion of the beta' subunit from a library of cloned murine Chlamydia trachomatis DNA. Similar attempts to recover the alpha subunit were unsuccessful. Sequence analysis demonstrated that the beta subunit of RNA polymerase was located between genes encoding the L7/L12 ribosomal protein and the beta' subunit of RNA polymerase; this organization is reminiscent of the rpoBC operon of Escherichia coli. The C. trachomatis beta subunit overproduced in E. coli was used as an antigen in rabbits to make a polyclonal antibody to this subunit. Although this polyclonal antibody specifically immunoprecipitated the beta subunit from Chlamydia-infected cells, it did not immunoprecipitate core or holoenzyme. Immunoblots with this antibody demonstrated that the beta subunit appeared early in infection.

Levels of DNA methylation in diploid and SV40 transformed human fibroblasts

Total 5-methylcytosine (5mC) has been measured in the DNA of cultured human cells by HPLC chromatography. In agreement with other reports, the level of 5mC declines continuously during the serial passaging of diploid fibroblasts, strain MRC-5. On the contrary, fibroblasts infected with SV40, which have acquired most of the properties of transformed cells, maintain a constant level of 5mC, prior to dying out in the crisis period. MRC-5 and Werner's syndrome fibroblasts fully transformed and immortalised by SV40, also maintain a constant level of 5mC. These results indicate that the ability of cells to maintain DNA methylation is a necessary but not a sufficient step for immortalisation.

Polymorphisms in the umuDC region of Escherichia species

The umuDC operon of Escherichia coli encodes mutagenic DNA repair. The umuDC regions of multiple isolates of E. coli, E. alkalescens, and E. dispar and a single stock of E. aurescens were mapped by nucleotide hybridization. umuDC is located at one end of a conserved tract of restriction endonuclease sites either 12.5 or 14 kilobase pairs long. Rearrangements, including possible deletions, were seen in the polymorphic DNA flanking the conserved tract. Restriction site polymorphisms were not found around the DNA repair gene recA or polA. The junctions of the conserved region contain direct repeats of nucleotide sequences resembling the termini of the Tn3 group of transposons. Possible mechanisms for the generation of these variants are discussed.

Haematological abnormalities in mice continuously exposed to ethanol vapour

Mice exposed to high concentrations of ethanol vapour (25-38 mg/l of inhaled air) for 24 h develop leucopenia, neutropenia, lymphopenia, monocytopenia and thrombocytopenia but not anaemia or macrocytosis. Their bone marrows usually give normal deoxyuridine-suppressed values and contain normal numbers of granulocyte-macrophage progenitor cells and slightly reduced numbers of megakaryocytes. Mice exposed to lower concentrations of ethanol vapour (10-25 mg/l of inhaled air) for 20-43 days develop thrombocytopenia only and, like the mice exposed for 24 h, do not develop anaemia or macrocytosis. The bone marrows of mice exposed to ethanol for 24 h or for 20-43 days, did not show either megaloblastic or sideroblastic erythropoiesis. The data suggest that the ethanol-treated mouse may provide a useful model for the investigation of the mechanisms underlying some but not all of the ethanol-induced haematological changes seen in humans.

Acetaldehyde causes a prolongation of the doubling time and an increase in the modal volume of cells in culture

The effects of culturing four human cell lines--Raji, MOLT-4, WI-L2, and K562--in the presence of 10-360 microM acetaldehyde for 3-18 days have been investigated. Concentrations of 45-360 microM caused a prolongation of the cell doubling time, and those of 90-360 microM caused an increase in the modal cell volume and in the protein content per cell. The results indicate that relatively low concentrations of acetaldehyde cause an impairment of cell proliferation and an abnormality of cell growth in vitro and support the possibility that ethanol-derived acetaldehyde may be responsible for some aspects of tissue damage in chronic alcoholics, including the increase in the mean cell volume of erythrocytes. Three of the four cell lines studied showed a reduction and the fourth showed no change in modal cell volume after culture with 100 mM ethanol, suggesting that the macrocytosis of red cells induced by chronic alcoholism is not caused via some direct effect of ethanol on the erythron.

Intrahepatic kinetics of indium-111-labelled platelets

The intrahepatic kinetics of 111indium-labelled platelets have been studied using dynamic gamma camera scintigraphy immediately following injection. Platelets labelled in saline with 111In-oxine or 111In-acetylacetonate underwent rapidly reversible hepatic sequestration, indicating that they were "activated". Platelets labelled in plasma with 111In-tropolonate, however, did not display this phenomenon. On the assumption that plasma-labelled platelets display a normal initial bio-distribution, mean intrahepatic platelet transit time, as a factor of the transit time of 99m-Tc labelled red cells, was 1.45 +/- SE 0.12 (n = 6), implying the normal presence of a small intrahepatic platelet pool. Unlike the liver, transit through the spleen was not sensitive to the labelling medium; thus the mean intrasplenic transit time of plasma-labelled platelets was 9.3 +/- SE 0.7 min (n = 10), and of saline-labelled platelets 9.5 +/- SE 0.3 min (n = 8).

Pulmonary platelet kinetics in asthma

Platelets produce a range of bronchoconstrictor mediators. Measurements of plasma factors have implicated platelet activation in allergic asthma, and sensitised guinea pigs challenged with ovalbumin show pulmonary platelet aggregation accompanying bronchoconstriction. To investigate this further we injected autologous platelets labelled with indium 111 and red cells labelled with technetium 99m into three young volunteers with atopic asthma and three non-asthmatic volunteers and, after equilibration of platelets between blood and splenic pool, monitored lung 99mTc and 111In activities continuously. Comparison with the corresponding activities in blood samples allowed calculation of pulmonary platelet to red cell transit time ratio (tp/tr). This ratio was 0.9, 1.02, and 0.98 in the non-asthmatic subjects compared with 1.04, 0.97, and 1.17 in the asthmatic subjects. This argues against the existence of an intrapulmonary platelet pool in normal subjects; transpulmonary transit time was slightly prolonged in one asthmatic subject. Bronchial challenge with Dermatophagoides pteronyssinus was performed in the asthmatic subjects and monitoring continued for a further 30 minutes. Antigen induced falls in FEV1 of 20-50% were accompanied by small decreases in the 111In but not in the 99mTc lung signal. In line with this tp/tr fell to 0.89, 0.89, and 1.05. Antigen induced bronchoconstriction was therefore not accompanied by intrapulmonary platelet accumulation. Platelet survival was normal at 10.2 days in both groups of subjects.

The kinetics of unmatched and HLA-matched 111in-labelled homologous platelets in recipients with chronic marrow hypoplasia and anti-platelet immunity

The kinetics of homologous platelets, labelled in plasma with 111In-tropolonate, have been studied in five recipients with chronic marrow hypoplasia and severe thrombocytopenia, who were refractory to platelet transfusions as a result of alloimmunization. Mean platelet life span (MPLS), recovery, plasma 111In level and splenic and hepatic uptake kinetics were studied on two occasions, one using HLA-matched platelets and the other unmatched platelets. In each case, recovery of labelled platelets at 1 h post-injection and MPLS improved with HLA matching, although this improvement was highly variable. Only two of the five subjects would have derived any significant benefit from HLA-matched as compared with unmatched platelet transfusions. It was concluded that the need exists for additional cross-matching procedures, possibly related to platelet specific antigens, in patients who remain refractory to platelet transfusion.

Comparisons of the composition of fat cells obtained from the marrow of normal individuals or of subjects with aplastic anemia and from bone marrow cultures

The lipid composition of fat cells in the bone marrow of normal individuals and patients with aplastic anemia was investigated, using thin-layer and gas-liquid chromatography. The results were compared to those obtained from fat cells grown in vitro. Thin-layer chromatography (t.l.c) revealed that triacylglycerols were the major component of normal and aplastic marrow fat cells and of fat cells in culture. Analysis by gas-liquid chromatography (g.l.c) of the triacylglycerols, diacylglycerols, and nonesterified fatty acids detected minor differences between fat cells from normal and aplastic marrow. Although there were no statistically significant differences in the proportions of saturated fatty acids and their unsaturated analogues, the relative amounts of gamma-linolenic acid were increased in aplastic anemia and those of linoleic and myristoleic acids were reduced. In contrast, fat cells obtained from in vitro cultures contained a much higher proportion of unsaturated fatty acids. These findings indicate that there is no marked abnormality in the composition of bone marrow fat cells in aplastic anemia, but that minor differences can be detected; the fatty acid composition of bone marrow fat cells is not reproduced in vitro.

Early and late contact sensitivity reactions in guinea pigs senstitzed to oxazolone

Inbred strain 2 and random-bred guinea pigs injected oxazolone in incomplete or complete Freund's adjuvant showed contact reactions within an hour after topical application when tested 3 weeks post-sensititization. The application when tested 3 weeks post-sensitization. The time for appearance of skin reactions at 5 days post-sensitization was 8 to 24 hr, more along classic delayed-type hypersensitivity lines. Immune serum harvested several weeks after sensititazation was effective for passive transfer of early skin reactivity, while serum at 5 to 10 days was not. Lymph node cells taken 5 days after sensitization of donors could transfer only the late skin reactivity to histocompatible recipients; lymph nodes taken at 15 days did not contain cells capable of such transfers. The heterogeneity of mechanisms involved in the production of contact dermatitis suggested by these results provides new approaches to studies in this area of allergy research.