Patterns of Cancer Treatment among People with HIV in the Mountain West

PURPOSE/OBJECTIVE(S)

People with HIV (PWH) are more likely to get cancer than the general population, and cancer is a large and growing cause of morbidity and mortality in PWH. Cancer survival is significantly worse in PWH compared with uninfected people, due in part to lower rates of cancer treatment. There is a lack of high-quality data assessing treatment patterns for cancers diagnosed in PWH in the Mountain West region of the United States, which is underrepresented in HIV malignancy research funding and cancer clinical trial enrollment specific to this population. As such, the current project examined cancer data for two Mountain West states: Utah (UT) and Nevada (NV).

MATERIALS/METHODS

In UT, the majority of PWH are treated in the XXX healthcare system, therefore institutional data from 1992 - 2019 was used to identify cases of cancer among PWH in UT. In NV, cancer registry data linked with HIV registry data was anonymized and obtained from 1985 - 2017. Clinical and demographic features, as well as patterns of cancer treatment, are described in both cohorts. We did not pool data or make direct statistical comparisons between the cohorts given the incompatibility of data sources between the two states.

RESULTS

Of the 1,089 cases included in the study, 105 were identified in UT and 984 in NV. In both states, most cancer patients with HIV were White (68% UT, 75% NV) and male (78% UT, 86% NV). 23% of patients in Utah were uninsured or had unknown insurance, while 42% of patients in NV were uninsured/unknown. In UT, the most common cancers among PWH were hematologic (22%), gastrointestinal (16%), and genitourinary (13%). In NV, the most common cancers were gastrointestinal (23%), hematologic (20%), and skin (18%). Stage I was more common in UT (44%, 21% NV), while stage IV was more common in NV (35%, 29% UT). Overall, cancer treatment rates for PWH were numerically higher in UT (75%) compared to NV (55%). In UT, 48% of PWH received surgery, 36% received chemotherapy, and 12% received radiotherapy. In NV, 38% had surgery, 43% had chemotherapy, and 15% had radiation.

CONCLUSION

The study identified differences in PWH and cancer diagnosed in UT and NV, although direct statistical comparisons were not made. The number of PWH diagnosed with cancer in NV was higher, cancer stage was more advanced, and treatment rates were lower. These findings reflect higher HIV prevalence, with HIV rates 3x higher in NV vs. UT. Lower utilization of surgery in NV may reflect later stage at diagnosis. Treatment rates in both states were lower than typical for the general population, which may reflect limited access to tertiary medical centers with HIV and oncology specialists for rural patients in the Mountain West. Given lower cancer treatment infrastructure in NV and availability of clinical trials for PWH in UT, community engagement and collaboration between the two states may yield opportunities to improve access to cancer treatment and outcomes for PWH in the Mountain West.

Machine learning approach for distinguishing malignant and benign lung nodules utilizing standardized perinodular parenchymal features from CT

PURPOSE

Computed tomography (CT) is an effective method for detecting and characterizing lung nodules in vivo. With the growing use of chest CT, the detection frequency of lung nodules is increasing. Noninvasive methods to distinguish malignant from benign nodules have the potential to decrease the clinical burden, risk, and cost involved in follow-up procedures on the large number of false-positive lesions detected. This study examined the benefit of including perinodular parenchymal features in machine learning (ML) tools for pulmonary nodule assessment.

METHODS

Lung nodule cases with pathology confirmed diagnosis (74 malignant, 289 benign) were used to extract quantitative imaging characteristics from computed tomography scans of the nodule and perinodular parenchyma tissue. A ML tool development pipeline was employed using k-medoids clustering and information theory to determine efficient predictor sets for different amounts of parenchyma inclusion and build an artificial neural network classifier. The resulting ML tool was validated using an independent cohort (50 malignant, 50 benign).

RESULTS

The inclusion of parenchymal imaging features improved the performance of the ML tool over exclusively nodular features (P < 0.01). The best performing ML tool included features derived from nodule diameter-based surrounding parenchyma tissue quartile bands. We demonstrate similar high-performance values on the independent validation cohort (AUC-ROC = 0.965). A comparison using the independent validation cohort with the Fleischner pulmonary nodule follow-up guidelines demonstrated a theoretical reduction in recommended follow-up imaging and procedures.

CONCLUSIONS

Radiomic features extracted from the parenchyma surrounding lung nodules contain valid signals with spatial relevance for the task of lung cancer risk classification. Through standardization of feature extraction regions from the parenchyma, ML tool validation performance of 100% sensitivity and 96% specificity was achieved.

QTL involved in the modification of cyanidin compounds in black and red raspberry fruit

Fruit from Rubus species are highly valued for their flavor and nutritive qualities. Anthocyanin content contributes to these qualities, and although many studies have been conducted to identify and quantify the major anthocyanin compounds from various Rubus species, the genetic control of the accumulation of these complex traits in Rubus is not yet well understood. The identification of the regions of the genome involved in the production of anthocyanins is an important first step in identifying the genes underlying their expression. In this study, ultra and high-performance liquid chromatography (UHPLC and HPLC) and two newly developed Rubus linkage maps were used to conduct QTL analyses to explore the presence of associations between concentrations of five anthocyanins in fruit and genotype. In total, 27 QTL were identified on the Rubus linkage maps, four of which are associated with molecular markers designed from transcription factors and three of which are associated with molecular markers designed from anthocyanin biosynthetic pathway candidate genes. The results of this study suggest that, while QTL for anthocyanin accumulation have been identified on six of seven Rubus linkage groups (RLG), the QTL on RLG2 and RLG7 may be very important for genetic control of cyanidin modification in Rubus.

Construction of black (Rubus occidentalis) and red (R. idaeus) raspberry linkage maps and their comparison to the genomes of strawberry, apple, and peach

The genus Rubus belongs to the Rosaceae and is comprised of 600-800 species distributed world-wide. To date, genetic maps of the genus consist largely of non-transferable markers such as amplified fragment length polymorphisms. An F(1) population developed from a cross between an advanced breeding selection of Rubus occidentalis (96395S1) and R. idaeus 'Latham' was used to construct a new genetic map consisting of DNA sequence-based markers. The genetic linkage maps presented here are constructed of 131 markers on at least one of the two parental maps. The majority of the markers are orthologous, including 14 Rosaceae conserved orthologous set markers, and 60 new gene-based markers developed for raspberry. Thirty-four published raspberry simple sequence repeat markers were used to align the new maps to published raspberry maps. The 96395S1 genetic map consists of six linkage groups (LG) and covers 309 cM with an average of 10 cM between markers; the 'Latham' genetic map consists of seven LG and covers 561 cM with an average of 5 cM between markers. We used BLAST analysis to align the orthologous sequences used to design primer pairs for Rubus genetic mapping with the genome sequences of Fragaria vesca 'Hawaii 4', Malus × domestica 'Golden Delicious', and Prunus 'Lovell'. The alignment of the orthologous markers designed here suggests that the genomes of Rubus and Fragaria have a high degree of synteny and that synteny decreases with phylogenetic distance. Our results give unprecedented insights into the genome evolution of raspberry from the putative ancestral genome of the single ancestor common to Rosaceae.

Variability in drug formularies and implications in decision support

Formularies are highly variable, which limits physicians ability to prescribe cost effective medications for their patients. In this study we explore the composition of 3,346 formularies in terms of outpatient prescription coverage, medication class coverage, and cost implications. Our analysis revealed that 42% of formularies are duplicative and that the unique formularies contain variability for medications that contribute little in terms of cost or overall use. These results lead us to believe the number and complexities of formularies can be dramatically reduced leading to more intuitive decision support for physicians when writing prescriptions.

Adrenergic receptors modulate motoneuron excitability, sensory synaptic transmission and muscle spasms after chronic spinal cord injury

The brain stem provides most of the noradrenaline (NA) present in the spinal cord, which functions to both increase spinal motoneuron excitability and inhibit sensory afferent transmission to motoneurons (excitatory postsynaptic potentials; EPSPs). NA increases motoneuron excitability by facilitating calcium-mediated persistent inward currents (Ca PICs) that are crucial for sustained motoneuron firing. Spinal cord transection eliminates most NA and accordingly causes an immediate loss of PICs and emergence of exaggerated EPSPs. However, with time PICs recover, and thus the exaggerated EPSPs can then readily trigger these PICs, which in turn produce muscle spasms. Here we examined the contribution of adrenergic receptors to spasms in chronic spinal rats. Selective activation of the α(1A) adrenergic receptor with the agonists methoxamine or A61603 facilitated Ca PIC and spasm activity, recorded both in vivo and in vitro. In contrast, the α(2) receptor agonists clonidine and UK14303 did not facilitate Ca PICs, but did decrease the EPSPs that trigger spasms. Moreover, in the absence of agonists, spasms recorded in vivo were inhibited by the α(1) receptor antagonists WB4010, prazosin, and REC15/2739, and increased by the α(2) receptor antagonist RX821001, suggesting that both adrenergic receptors were endogenously active. In contrast, spasm activity recorded in the isolated in vitro cord was inhibited only by the α(1) antagonists that block constitutive receptor activity (activity in the absence of NA; inverse agonists, WB4010 and prazosin) and not by the neutral antagonist REC15/2739, which only blocks conventional NA-mediated receptor activity. RX821001 had no effect in vitro even though it is an α(2) receptor inverse agonist. Our results suggest that after chronic spinal cord injury Ca PICs and spasms are facilitated, in part, by constitutive activity in α(1) adrenergic receptors. Additionally, peripherally derived NA (or similar ligand) activates both α(1) and α(2) adrenergic receptors, controlling PICs and EPSPs, respectively.

Changes in gene expression during pegylated interferon and ribavirin therapy of chronic hepatitis C virus distinguish responders from nonresponders to antiviral therapy

Treating chronic hepatitis C virus (HCV) infection using pegylated alpha interferon and ribavirin leads to sustained clearance of virus and clinical improvement in approximately 50% of patients. Response rates are lower among patients with genotype 1 than with genotypes 2 and 3 and among African-American (AA) patients compared to Caucasian (CA) patients. Using DNA microarrays, gene expression was assessed for a group of 33 African-American and 36 Caucasian American patients with chronic HCV genotype 1 infection during the first 28 days of treatment. Results were examined with respect to treatment responses and to race. Patients showed a response to treatment at the gene expression level in RNA isolated from peripheral blood mononuclear cells irrespective of degree of decrease in HCV RNA levels. However, gene expression responses were relatively blunted in patients with poor viral response (<1.5 log(10)-IU/ml decrease at 28 days) compared to those in patients with a marked (>3.5 log(10)-IU/ml decrease) or intermediate (1.5 to 3.5 log(10)-IU/ml decrease) response. The number of genes that were up- or down-regulated by pegylated interferon and ribavirin treatment was fewer in patients with a poor response than in those with an intermediate or marked viral response. However AA patients had a stronger interferon response than CA patients in general. The induced levels of known interferon-stimulated genes such as the 2'5'-oligoadenylate synthetase, MX1, IRF-7, and toll-like receptor TLR-7 genes was lower in poor-response patients than in marked- or intermediate-response patients. Thus, the relative lack of viral response to interferon therapy of hepatitis C virus infection is associated with blunted interferon cell signaling. No specific regulatory gene could be identified as responsible for this global blunting or the racial differences.

Early corrective reactions of the leg to perturbations at the torso during walking in humans

The contribution of afferent feedback to the regulation of locomotion in humans is not well understood. Animal experiments have suggested that loading of the leg during the stance phase may enhance the magnitude of extensor burst activity and delay the onset of swing phase. The aim of the present study was to determine whether transient loading of the leg at the end of stance would enhance extensor-muscle activity and delay the onset of swing in walking humans. To test this hypothesis, we applied loads to the hips of subjects so that the load was applied along the long axis of the leg at the end of stance (down-back unsupported, DBU). This resulted in an unexpectedly complex reaction characterised by rapid co-contraction of antagonist pairs of muscles around the ankle and knee and a prolongation of the stance phase. We speculated that the complexity of the reaction was, in part, due to a disturbance in equilibrium. To address this possibility, two additional perturbation paradigms were tested: (1) subjects held a rail during the loading paradigm (down-back supported, DBS), or (2) subjects received only a posteriorly directed perturbation of the hips, which added no additional load to the leg (backward unsupported, BU). As predicted, the DBS perturbation resulted in an enhancement of the ongoing soleus-muscle activity, and the unexpected tibialis anterior burst that was observed during the DBU paradigm was absent. Allowing the subjects to hold a rail substantially reduced the change in the timing of the step cycle observed in the DBU paradigm. The BU perturbation prolonged the stance phase duration and, as expected, resulted in a burst of activity in tibialis activity. This was usually accompanied by a reduction in the ongoing soleus activity. Two important conclusions are drawn from the present study. First, loading of the leg at the end of stance phase enhances the ongoing extensor-muscle activity. We suggest that afferent feedback responding to the increase load supported by the leg leads to rapid enhancement of the active extensor muscles to compensate for the increased load and prevent collapse of the leg. Interestingly, the duration of the stance phase was only marginally increased when loading was applied without a postural disturbance (DBS). Second, posterior perturbation of the centre of mass at the end of stance phase evokes an "automatic postural response" in tibialis anterior. Of particular interest, this evoked postural response can occur simultaneously with an enhanced activation of soleus. This indicates that the DBU perturbation employed in this study elicited two responses, one to prevent the collapse of the leg and the other to stabilise the centre of mass.

Loading during the stance phase of walking in humans increases the extensor EMG amplitude but does not change the duration of the step cycle

Prior work from mammals suggests that load experienced by extensor muscles of the hindlimbs (i.e. Duysens and Pearson 1980; Pearson and Collins 1993; Fouad and Pearson 1997) or cutaneous afferents from the plantar surface of the foot (Duysens and Pearson 1976; Guertin et al. 1995) enhances activity in extensor muscles during the stance phase, and delays the onset of flexor activity associated with the swing phase. The presumed functional significance of this phenomenon is that extensor activity of the supporting limb during walking can: (a) reinforce the supporting function in proportion to the load experienced, and (b) prolong the stance phase until unloading of the limb has occurred. Whether a similar functional role exists for load-sensitive afferents during walking in the human is unknown. In this study, the effect of adding or removing a substantial load (30% of body weight) at the centre of mass was studied in healthy adult human subjects. Loads were applied near the centre of mass to avoid the need for postural adjustments which might confound the interpretation of the results. Subjects walked on a treadmill with either: (a) a sustained increase or decrease in load, or (b) a sudden unexpected increase or decrease in load. In general, subjects responded to the changes in load by changing the amplitude of the extensor electromyographic (EMG) bursts. For example, with sudden unexpected additions in load, the average increase in amplitude was 40% for the soleus across the stance phase, and 134% for the quadriceps during the early part of the stance phase. Extensor EMGs increased with both sustained and sudden increases in load. Extensor EMG durations also increased (average increase in duration of 4% for soleus with sudden loading, and 7% for sustained loading). Cycle duration hardly changed (average increase of 0.5% with both sudden and sustained loading). These results differ from those of infants subjected to a similar perturbation during supported walking. A large change in timing (i.e. an increase in the duration of the stance phase by 30% and the step cycle by 28%) was seen in the infants, with no change in the amplitude of the EMG burst (Yang et al. 1998). These results suggest that the central nervous system can control the timing and amplitude of extensor EMG activity in response to loading independently. Maturation of the two components most likely occurs independently. In the adult, independent control of the two components may provide greater flexibility of the response.

Transient disturbances to one limb produce coordinated, bilateral responses during infant stepping

Transient disturbances were applied to the lower limbs of infants (3-10 mo of age) while they were supported to stepped on a treadmill. The aim was to determine how stepping infants respond to novel disturbances that would disrupt equilibrium during independent walking. Their responses were also compared with those from lower mammals and adult humans. In the first series of experiments, the motion of the limb in the swing phase was transiently stopped by the experimenter grasping the limb for a short time (0.1-1.7 s). During such disturbances, the stance phase was prolonged in the contralateral limb, and the onset of the swing phase was delayed. The degree to which the stepping was modified in the contralateral limb depended on the amount of load experienced by that limb. If the contralateral limb was bearing very little weight at the time of the disturbance, its rhythm did not change appreciably. In the second series of experiments, load was added to the infant by pushing down on the pelvis during the stance phase. This greatly prolonged the stance phase and delayed the swing phase. It did not increase the amplitude of the extensor electromyogram (EMG) of the loaded limb. In conclusion, the neural circuitry controlling stepping in the infants responds to disturbances in an organized fashion that is conducive to maintaining equilibrium and forward progression.

Infant stepping: a method to study the sensory control of human walking

1. Stepping responses were studied in infants between the ages of 10 days and 10 months while they were supported to step on a slowly moving treadmill belt. Surface electromyography (EMG) from muscles in the lower limb, force exerted by the feet on the treadmill belt, and the motion of the lower limbs were recorded. 2. Two groups of infants were studied, those who had a small amount of daily practice in stepping and those who did not. Practice resulted in a dramatic increase in the incidence of stepping recorded in the laboratory, particularly for the periods between 1 and 6 months of age. 3. The majority of infants showed clear alternation between the flexor and extensor muscles during walking, regardless of age. Co-contraction between flexors and extensors, estimated by the overlap in area between rectified and smoothed EMG from a muscle pair, was greater for some muscle groups in the infant compared with the adult. 4. Practice resulted in a significantly lower co-contraction index for the tibialis anterior- quadriceps muscle pair. Practice did not affect the mean step cycle duration. 5. Infants of all ages could step at a range of treadmill speeds by adjusting their step cycle duration. The relationship between the treadmill speed and cycle duration was well fitted by a power function, similar to those reported for intact cats and adult humans. The change in step cycle duration resulted almost entirely from a change in the extensor burst duration, whereas the flexor burst duration remained constant. 6. Airstepping could be elicited in some infants. The cycle durations for airstepping were close to the shortest cycles recorded on the treadmill. 7. In conclusion, the system for generating rhythmic, alternating activity of the lower limbs for stepping is clearly developed by birth. The stepping is sustained and regular, particularly if stepping practice is incorporated briefly each day. The infant population provides a good subject pool for studying the afferent control of walking in the human, before cerebral influences are fully developed. The characteristics and maturity of the system remain to be determined.

Measurement of rigidity in Parkinson's disease

Clinical assessment of rigidity in parkinsonian patients is largely qualitative. The reliability and validity of the assessments are sometimes in doubt. Several "engineering" methods of quantifying rigidity have been described, but none has been adopted into general clinical practice. A possible reason is that these methods differ in crucial aspects from the clinical exam. We therefore tackled the problem by monitoring the clinical exam itself, using small sensors to measure the forces and displacements applied. Limb impedance (Z) was computed using parameter identification methods and compared to raters' verbalized ratings of rigidity based on a 5-point scale: the Unified Parkinson's Disease Rating System. The qualitative and quantitative estimates of impedance covaried over a fourfold range, depending on the forces imposed and the subject's motor set. Raters differed by up to 1 full point in their mean qualitative ratings and sometimes disagreed on whether levodopa reduced rigidity. This was not due to any significant differences in the overall range of rigidity they evoked, but rather to the way they scored this range [the ratio of mean rating to mean impedance (R/Z) varied between raters and subjects]. On the other hand, the R/Z ratio was reproducible over separate sets of ratings and may therefore serve to convert measured impedance into a standardized rating. Our results indicate that the current clinical exam may be too abbreviated to detect the sometimes quite small reductions in rigidity after levodopa. We conclude that a device that conveniently quantifies the clinical assessment of rigidity is now available and will lead to more standardized protocols for rating rigidity in the near future.

Short latency, non-reciprocal group I inhibition is reduced during the stance phase of walking in humans

Activation of group Ib afferents from extensor muscles produces an inhibition in the parent muscle and its synergists in a resting cat. This reflex switches to excitation of the parent muscle and its synergists when the cat walks. This study determined if a similar reflex undergoes the same type of reversal in the intact human. A putative Ib reflex was elicited by conditioning the Hoffmann (H) reflex in the soleus muscle with stimuli to the nerve innervating the medial gastrocnemius muscle. The reflex was observed while subjects: (1) sat quietly; (2) sat and activated the triceps surae muscle isometrically at a low level; (3) stood and activated the triceps surae to the same level as (2); and (4) walked on a treadmill. Condition-test intervals of 1 to 16 ms were used. Ten out of the 15 subjects studied in quiet sitting showed an early, presumably disynaptic inhibition. Walking resulted in a significant reduction in the size of this inhibition at condition-test intervals of 4, 5, 6, and 8 ms for these subjects. No significant differences were observed at longer condition-test intervals. As a group, the inhibition of the conditioned H-reflex was diminished during walking, but not significantly excited. Four out of the 10 subjects, however, showed a significant excitation of the conditioned H-reflex during walking. The inhibition was significantly reduced at a condition-test interval of 7 ms when the triceps surae group was activated isometrically. No differences were seen in the reflex between matched levels of contraction in sitting and standing. It is concluded that the short latency group I inhibition seen at rest is reduced during walking, in a manner similar to that seen in spinal and decerebrate cats. The reduction may be accounted for, at least partially, by activation of the triceps surae.

Disynaptic group I excitation of synergist ankle extensor motoneurones during fictive locomotion in the cat

1. Intracellular recording from medial gastrocnemius (MG) motoneurones was used to examine postsynaptic potentials produced by electrical stimulation of the plantaris nerve at group I strength at rest and during fictive locomotion. Fictive locomotion was evoked by stimulation of the midbrain locomotor region (MLR) in decerebrate cats or in decerebrate, acute low-spinal cats by perineal stimulation following intravenous administration of clonidine and naloxone. 2. In both MLR and spinal fictive locomotor preparations, stimulation of plantaris nerve group I afferents at rest evoked short-latency (< 2 ms) IPSPs in MG motoneurones. During the extensor phase of MLR-evoked locomotion, the same stimulation produced short-latency (1.6-1.8 ms) EPSPs. Such latencies suggest mediation by one interneurone interposed between plantaris nerve group I afferents and MG motoneurones. Non-monosynaptic, short-latency excitation was not seen at rest nor during the flexion phase of the step cycle. 3. Group I EPSPs during the extensor phase of MLR-evoked locomotion were evoked by stimulation at intensities ranging from 1.4-2 times threshold (T). The effectiveness of stimulation intensities < 1.5 T suggests that activation of group II afferents is not required to evoke disynaptic excitation. Selective activation of group Ia afferents by stretches of the Achilles tendon also produced disynaptic EPSPs during extension. 4. During fictive locomotion in spinal animals pretreated with clonidine, short-latency group I EPSPs were not seen but group I IPSPs recorded at rest disappeared or were greatly attenuated. The failure of depolarizing current to reveal group I IPSPs suggests that fictive locomotion involves an inhibition of the inhibitory interneurones that operate at rest. In both clonidine-treated spinal and MLR preparations, trains of stimuli at group I strength evoked longer-latency and slowly rising potentials that were more prominent during the flexor phase of fictive locomotion. 5. These results show a reduction in short-latency group I inhibition of synergists in both MLR and clonidine-treated spinal preparations during fictive locomotion. In addition, activation of group I afferents evokes short-latency excitation of synergists during extension in the MLR preparation. Such excitatory reflexes activated by ankle extensor group Ia and Ib afferents may form an excitatory feedback system, reinforcing on-going extensor activity during the stance phase of the step cycle.

Image analysis studies of the degree of irreversible deformation of sickle cells in relation to cell density and Hb F level

We analyzed, quantitatively by image analysis, the degree of irreversible deformation of red cells (SS cells) from patients with homozygous sickle cell disease, and studied the relationships among the degree of irreversible cell deformation, cell density, and Hb F level. SS cells from 25 patients (aged 1-36 years) whose Hb F levels ranged from 2.5% to 40.0%, were fully oxygenated and then were separated into four fractions by density centrifugation. Every fraction was studied for morphology and Hb F content. We found that the irreversible deformation of SS cells from the circulation occurred mainly by elongation and that the degree of elongation was extremely variable. We also found that in the cells of patients with Hb F levels < 20% the degree of irreversible elongation increases as cell density increases, suggesting that dehydration occurs concomitantly with irreversible elongation. Statistical analysis (Student t test) indicated that there were significant differences (P = 0.008 or < 0.001) in the degree of elongation among density-fractionated SS cells from patients with Hb F < 20%, although there was no significant difference (P > 0.1) among those from patients with Hb F > or = 20%. We also found that cell density increased as Hb F level of the density fraction decreased in all patients with Hb F < 20% but not always in those with Hb F > or = 20%. This suggests that cells with lower Hb F levels are selectively susceptible to dehydration. Furthermore, we found that the mean degree of irreversible elongation decreases linearly with increasing levels of Hb F and reaches the normal range at 21-24%. Since the degree of irreversible deformation of SS cells quantified by image analysis is directly related to cell density, and inversely to Hb F levels, mechanical stress or membrane damage caused by Hb S polymerization may be an important factor in the formation of dense cells in vivo.

Contribution of the ryanodine-sensitive fraction to capabilities of cardiac SR

The contribution of the ryanodine-sensitive fraction of canine cardiac sarcoplasmic reticulum to the total issue calcium uptake was estimated by the oxalate-supported calcium uptake rate in canine whole heart homogenates. Ryanodine stimulated this uptake rate nearly three-fold. Ryanodine stimulated this same activity in isolated SR vesicles only two-fold. An analysis of the yield of calcium uptake activity throughout the isolation procedure showed that the largest discrimination between ryanodine-sensitive and ryanodine-insensitive activity occurs at the first centrifugation step. In isolated vesicles, the initial rate of uptake in the absence of oxalate correlated well with the sustained oxalate-support calcium uptake rate, suggesting that oxalate-supported calcium uptake is a good indicator of in vivo SR function. The similarity between the effects of ryanodine on the rate and capacity of calcium uptake in the presence or absence of oxalate is consistent with earlier observations that ryanodine adds effective volume by closing a calcium release channel in a subpopulation of SR. The data also suggest that the ratio of calcium pumping activity to volume in these two populations is not greatly different.

Binding of cholera toxin to Giardia lamblia

Binding of cholera toxin to Giardia lamblia was demonstrated by two slightly different methods: an immunofluorescence technique using antibody to cholera toxin and anti-rabbit immunoglobulin G conjugated to fluorescein isothiocyanate, and a one-step fluorescence method in which G. lamblia was incubated with the B subunit of cholera toxin conjugated to fluorescein isothiocyanate.

Gastric and intestinal bleeding in multiple neurofibromatosis with cardiomyopathy

A case of multiple neurofibromatosis is described with histologically divergent lesions in the jejunum, stomach and colon presenting with bleeding and complicated by idiopathic hypertrophic subaortic stenosis. An aggressive surgical approach to gastro-intestinal bleeding in multiple neurofibromatosis is recommended.

Fentanyl and diazepam in endoscopy of the upper gastrointestinal tract

To compare the effect of fentanyl, a short-acting narcotic analgesic, with that of diazepam as intravenous premedication for endoscopy of the upper gastrointestinal tract, we allocated at random 200 consecutive outpatients requiring elective endoscopy to receive either fentanyl or diazepam; the procedure was evaluated both by the endoscopist and by the patient. The endoscopists' opinion of the ease of the procedure was significantly better for the group of patients who received fentanyl than for the group who received diazepam (P less than 0.001). The patients' opinion of the procedure was not influenced by the premedication used. No serious side effects were observed in either patient group. We concluded that fentanyl has significant advantages over diazepam as premedication for endoscopy of the upper gastrointestinal tract.

Importance of soil moisture and temperature on the growth of improved pasture on the Northern Tablelands of New South Wales

A simple model for predicting pasture growth from climatic data was developed and tested against experimental data. The model was used to analyse climatic data from a 24-yr period (1950–1973) to elucidate the relative importance of soil moisture and temperature on the growth of improved pastures on the Northern Tablelands of New South Wales, and to predict the year-to-year variations in total pasture growth.Predicted yearly dry matter production varied between extremes of 5000 kg ha-1 yr-1 in 1965 and 14,000 kg ha-1 yr-1 in 1971. Soil moisture was the major factor limiting pasture growth from the beginning of October until the end of May, and temperature was the major limiting factor from the end of May to early October. During May and October there was a period when both factors had a similar probability of being the most limiting factor. Variations in soil moisture caused greater within-year variability in pasture growth than temperature except in April and September when variability caused by temperature equalled that caused by soil moisture. The significance of these effects is discussed.