Spatial omics techniques and data analysis for cancer immunotherapy applications

In-depth profiling of cancer cells/tissues is expanding our understanding of the genomic, epigenomic, transcriptomic, and proteomic landscape of cancer. However, the complexity of the cancer microenvironment, particularly its immune regulation, has made it difficult to exploit the potential of cancer immunotherapy. High-throughput spatial omics technologies and analysis pipelines have emerged as powerful tools for tackling this challenge. As a result, a potential revolution in cancer diagnosis, prognosis, and treatment is on the horizon. In this review, we discuss the technological advances in spatial profiling of cancer around and beyond the central dogma to harness the full benefits of immunotherapy. We also discuss the promise and challenges of spatial data analysis and interpretation and provide an outlook for the future.

The promise and challenge of spatial omics in dissecting tumour microenvironment and the role of AI

Growing evidence supports the critical role of tumour microenvironment (TME) in tumour progression, metastases, and treatment response. However, the in-situ interplay among various TME components, particularly between immune and tumour cells, are largely unknown, hindering our understanding of how tumour progresses and responds to treatment. While mainstream single-cell omics techniques allow deep, single-cell phenotyping, they lack crucial spatial information for in-situ cell-cell interaction analysis. On the other hand, tissue-based approaches such as hematoxylin and eosin and chromogenic immunohistochemistry staining can preserve the spatial information of TME components but are limited by their low-content staining. High-content spatial profiling technologies, termed spatial omics, have greatly advanced in the past decades to overcome these limitations. These technologies continue to emerge to include more molecular features (RNAs and/or proteins) and to enhance spatial resolution, opening new opportunities for discovering novel biological knowledge, biomarkers, and therapeutic targets. These advancements also spur the need for novel computational methods to mine useful TME insights from the increasing data complexity confounded by high molecular features and spatial resolution. In this review, we present state-of-the-art spatial omics technologies, their applications, major strengths, and limitations as well as the role of artificial intelligence (AI) in TME studies.

Immunohistochemical scoring of CD38 in the tumor microenvironment predicts responsiveness to anti-PD-1/PD-L1 immunotherapy in hepatocellular carcinoma

Introduction

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-associated mortality globally. Immune-checkpoint blockade (ICB) is one of the systemic therapy options for HCC. However, response rates remain low, necessitating robust predictive biomarkers. In the present study, we examined the expression of CD38, a molecule involved in the immunosuppressive adenosinergic pathway, on immune cells present in the tumor microenvironment. We then investigated the association between CD38 and ICB treatment outcomes in advanced HCC.

Methods

Clinically annotated samples from 49 patients with advanced HCC treated with ICB were analyzed for CD38 expression using immunohistochemistry (IHC), multiplex immunohistochemistry/immunofluorescence (mIHC/IF) and multiplex cytokine analysis.

Results

IHC and mIHC/IF analyses revealed that higher intratumoral CD38⁺ cell proportion was strongly associated with improved response to ICB. The overall response rates to ICB was significantly higher among patients with high proportion of total CD38⁺cells compared with patients with low proportion (43.5% vs 3.9%, p=0.019). Higher responses seen among patients with a high intratumoral CD38⁺cell proportion translated to a longer median progression-free survival (mPFS, 8.21 months vs 1.64 months, p=0.0065) and median overall survival (mOS, 19.06 months vs 9.59 months, p=0.0295). Patients with high CD38⁺CD68⁺macrophage density had a better mOS of 34.43 months compared with 9.66 months in patients with low CD38⁺CD68⁺ macrophage density. CD38^hi macrophages produce more interferon γ (IFN-γ) and related cytokines, which may explain its predictive value when treated with ICB.

Conclusions

A high proportion of CD38⁺ cells, determined by IHC, predicts response to ICB and is associated with superior mPFS and OS in advanced HCC.

Applications of the pulsatile flow versatile ECLS: in vivo studies

INTRODUCTION

T-PLS (Twin-Pulse Life Support) is the first commercial pulsatile ECLS (Extra Corporeal Life Support) device (1). The dual sac structure of T-PLS can effectively reduce high membrane oxygenator inlet pressure and hemolysis. To verify both the use of T-PLS for ECLS and the advantages of T-PLS, we tested various models.

METHOD AND RESULTS

In the partial CPB (cardio pulmonary bypass) model (swine), T-PLS (N = 6), and Biopump (N = 2), a single pulsatile pump (N = 2), were compared. In the case of single pulsatile flow, during pump systole, pressure increased to 700 - 800 mmHg at the inlet port of the membrane oxygenator. fHb, a hemolysis measurement value, was about 80 mg/dL at 3 hours. On the contrary, because of T-PLS's dual sac system, the pressure of T-PLS had a maximum value of about 250 mmHg and fHb was similar to that of the commercial centrifugal pumps. In the total CPB model (bovine, N = 6), the heart was stopped via cardioplegia (Kcl). T-PLS flow was maintained at 3.0-4.5 L/min. T-PLS functioned like a natural heart, having a pulse pressure of 26-43 mmHg and a pulse rate of 40-60 bpm (beats per minute). In the emergency case model (canine, N = 6), T-PLS was started 10 minutes after cardiac arrest from electronic shock. In spite of cardiac arrest for a period of 40 minutes, the heart was recovered after defibrillation. In the ARDS (Acute Respiratory Distress Syndrome) model (canine, N = 6), minimal ventilator parameters were set: tidal volume 130 ml, respiration rate = bpm, FiO2 = 10%. Three hours after starting T-PLS, PO2 of the carotid artery blood (after 2 hours: 195 +/- 89.4; after 3 hours: 258 +/- 99.3 mmHg) was above half the value of the femoral artery but was within normal range.

CONCLUSION

It is suggested that a portable pulsatile ECLS like T-PLS may be used as a CPB device and as an alternative CPR (cardiopulmonary resuscitation) device in the case of cardiac arrest. Due to the pulsatile flow, oxygenated blood is delivered to the patient without overloading the ARDS patients heart.

Regulation of C. elegans DAF-16 and its human ortholog FKHRL1 by the daf-2 insulin-like signaling pathway

C. elegans insulin-like signaling regulates metabolism, development, and life span. This signaling pathway negatively regulates the activity of the forkhead transcription factor DAF-16. daf-16 encodes multiple isoforms that are expressed in distinct tissue types and are probable orthologs of human FKHRL1, FKHR, and AFX. We show that human FKHRL1 can partially replace DAF-16, proving the orthology. In mammalian cells, insulin and insulin-like growth factor signaling activate AKT/PKB kinase to negatively regulate the nuclear localization of DAF-16 homologs (reviewed in ). We show that the absence of AKT consensus sites on DAF-16 is sufficient to cause dauer arrest in daf-2(+) animals, proving that daf-16 is the major output of insulin signaling in C. elegans. FKHR, FKRHL1, and AFX may similarly be the major outputs of mammalian insulin signaling. daf-2 insulin signaling, via AKT kinases, negatively regulates DAF-16 by controlling its nuclear localization. Surprisingly, we find that daf-7 TGF-beta signaling also regulates DAF-16 nuclear localization specifically at the time when the animal makes the commitment between diapause and reproductive development. daf-16 function is supported by the combined action of two distinct promoter/enhancer elements, whereas the coding sequences of two major DAF-16 isoforms are interchangeable. Together, these observations suggest that the combined effects of transcriptional and posttranslational regulation of daf-16 transduce insulin-like signals in C. elegans and perhaps more generally.

Loads in the lumbar spine during traction therapy

The purpose of the present study was to determine the loads acting on the lumbar spine when traction therapy was given in the Fowler's position. The study had two parts: a theoretical analysis which showed that traction produced a flexion moment on the spine as well as axial distraction; and an experimental study which measured the flexion moment induced by the adoption of the Fowler's position. The Fowler's position is clinically essential in that it flexes the spine and takes up the slack of the posterior tissues before the traction force is applied. Hence the axial tension and flexion moment generated by the traction force are more effective in stretching the posterior tissues. The angle of pull on the traction harness influences the friction between the body and the couch. However, this consideration is not necessary if a split traction table is used. The mechanical effects of traction are compared with those produced by postero-anterior mobilisation. The relative magnitude and direction of loads produced, and their variation with segmental level should be considered by therapists when choosing a technique for treating low back pain.

Time course of stress relaxation and recovery in human ankles

OBJECTIVE

To characterise the time course of stress relaxation and recovery from stress relaxation in human ankles.

DESIGN

Two experiments were conducted. The first used a randomised within-subjects design, and the second used a randomised between-subjects regression design.

BACKGROUND

Several studies have described the time course of stress relaxation in human joints, but most have looked only at the effects of short durations of stretch. The time course of recovery from stretch in human ankles has not been documented.

METHODS

In the first experiment, one ankle of each of eight subjects was stretched to a fixed dorsiflexion angle for 20 min. The ankle was then released for 2 min (during which time subjects either remained relaxed or performed isometric contractions), then stretched again. In a second experiment, on 24 subjects, the ankle was stretched for 20 min, then released between 0 and 20 min, then stretched again. In both experiments, subjects remain relaxed and ankle torque was measured continuously.

RESULTS

When a constant-angle stretch was applied to the ankle, torque declined bi-exponentially towards an asymptote that was 58% of the initial torque. Nearly 5 min of stretch were required to obtain half of the maximal possible stress relaxation. Torque had recovered by 43% within 2 min of the release of stretch, but the degree of recovery did not appear to depend on whether subjects remained relaxed or performed isometric contractions. The time course of recovery was similar to the time course of stress relaxation.

CONCLUSIONS

Long duration stretches are required to produce a large proportion of the maximal possible stress relaxation. Recovery is initially rapid when the stretch is released.

RELEVANCE

These data provide a description of the time course of the effects of stretch, and of the subsequent relief of stretch, on mechanical properties of human ankles.

Kinematics of rotational mobilisation of the lumbar spine

OBJECTIVE

The purposes of this study were to measure the movements of the lumbar spine produced by rotational mobilisation, and to study the effects of different grades of mobilisation on the movements produced.

DESIGN

Kinematics of rotational mobilisation was assessed with an electromagnetic tracking device.

BACKGROUND

Rotational mobilisation is frequently used in the treatment of back pain, but there was no information on its mechanical effects.

METHODS

Movements of the lumbar spine were measured in 14 healthy volunteers when they were subjected to grades I to IV left rotational mobilisation.

RESULTS

In the starting positions, the spines were found to be flexed, axially rotated to the left and laterally bent to the right. As the mobilisation grade increased, the spine was axially rotated further into the range. Rotational mobilisation was found to produce oscillatory movements of the lumbar spine in all three anatomical planes. It produced axial rotation which was accompanied by lateral bending in the opposite direction and sagittal rotation. The mean frequency of the oscillatory movements was 1.4 Hz. The amplitude of the oscillations was small, and was found to be increased in grades II and III mobilisation.

CONCLUSION

Rotational mobilisation may be able to restore lost movements of the lumbar spine in any of the three anatomical planes.

Constitutive expression of the steroid sulfatase gene supports the growth of MCF-7 human breast cancer cells in vitro and in vivo

Many human breast tumors are driven by high intratumor concentrations of 17beta-estradiol that appear to be locally synthesized. The role of aromatase is well established, but the possible contribution of the steroid sulfatase (STS), which liberates estrogens from their biologically inactive sulfates, has been inadequately assessed and remains unclear. To evaluate the role of STS further, we transduced estrogen-dependent MCF-7 human breast cancer cells with a retroviral vector directing the constitutive expression of the human STS gene. Gene integration was confirmed by Southern hybridization, production of the appropriately sized messenger RNA by Northern hybridization, and expression of functional protein by metabolism of [(3)H]estrone sulfate to [(3)H]estrone. Maximum velocity estimates of estrone formation are 64.2 pmol estrone/mg protein.h in STS-transduced cells (STS Clone 20), levels comparable to those seen in some human breast tumors. Lower levels of endogenous activity are seen in MCF-7 cells (13.0 pmol estrone/mg protein.h) and in cells transduced with vector lacking the STS gene (Vector 3 cells; 12.0 pmol estrone/mg protein.h). 17beta-Estradiol sulfate induces expression of the progesterone receptor messenger RNA only in STS Clone 20 cells, whereas estrone sulfate produces the greatest stimulation of anchorage-independent growth in these cells. STS Clone 20 cells retain responsiveness to antiestrogens, which block the ability of estrogen sulfate to increase the proportion of cells in both the S and G(2)/M phases of the cell cycle. Consistent with these in vitro observations, only STS Clone 20 cells exhibit a significant increase in the proportion of proliferating tumors in nude ovariectomized mice supplemented with 17beta-estradiol sulfate. The primary activity in vivo appears to be from intratumor STS, rather than hepatic STS. Surprisingly, 17beta-estradiol sulfate appears more effective than 17beta-estradiol when both are administered at comparable concentrations. This effect, which is seen only in STS Clone 20 cells, may reflect differences in the cellular pharmacology of exogenous estrogens compared with those released by the activity of intracellular STS. These studies directly demonstrate that intratumor STS activity can support estrogen-dependent tumorigenicity in an experimental model and may contribute to the promotion of human breast tumors.

The role of spinal tissues in resisting posteroanterior forces applied to the lumbar spine

OBJECTIVE

To determine the effects of the dissection of spinal tissues on the mechanical behavior of motion segments under the application of posteroanterior forces.

DESIGN

A cadaveric motion segment study.

SETTING

A tissue mechanics research laboratory.

PROCEDURE

Anterior shear and extension moment were applied to 10 motion segments to simulate the clinical situation when posteroanterior forces were applied to the spine. The movements of the specimens in the sagittal plane were studied by a camera. Spinal tissues were dissected sequentially, and the mechanical testing was repeated after the dissection of each tissue.

RESULTS

The most significant movements produced were extension and superior translation of the anteroinferior corner of the superior vertebral body. Translational movements in the other directions were small. The dissection of the posterior ligaments and zygapophyseal joints did not lead to significant changes in the movements.

CONCLUSIONS

Injuries of the posterior ligaments are unlikely to alter the mechanical response of the spine to posteroanterior forces. However, these posterior tissues are pain sensitive and may be subjected to large strains and elicit symptoms.

Fatigue of abdominal and paraspinal muscles during sustained loading of the trunk in the coronal plane

OBJECTIVE

To measure fatigue-related changes in the electromyographic signals of trunk muscles during lateral bend loading, and to determine the effects of load magnitude, gender, and contraction time on these changes.

DESIGN

A factorial experimental design.

SETTING

A research laboratory.

PARTICIPANTS

Twenty-four healthy volunteers (12 men, 12 women; mean age +/- SD, 22.9 +/- 3.1 yrs).

INTERVENTION

Subjects sustained lateral bend loads at 20%, 40%, and 60% of their maximal exertion.

OUTCOME MEASURES

Median frequency and total power of the power spectrum of the electromyographic signals.

RESULTS

Trunk muscles' median frequency signals decreased and their total power increased as contraction time increased. These changes became more pronounced as the magnitude of loading increased. Men and women showed a similar rate of median frequency decline, but the total power of signals in men was larger than that in women. All muscles showed signs of fatigue, except that at 20% of maximal exertion only thoracic erector spinae fatigued significantly.

CONCLUSIONS

Endurance training of paraspinal and abdominal muscles may be useful in preventing low back pain associated with lateral bend loading. The risk of back pain is similar in both genders and is higher with larger load magnitude and longer contraction time.

Passive moment about the hip in straight leg raising

OBJECTIVE

The purpose of this examine is to study the load-deformation characteristics of the hip in straight leg raising.

DESIGN

An experimental study in which passive moment about the hip was determined as a function of hip angle.

BACKGROUND

Straight leg raising is widely employed in clinical examination, and there is little information on its mechanical characteristics.

METHODS

Fourteen healthy volunteers were recruited for this study. Three trials of straight leg raise tests were performed while subjects lay supine on a plinth that was fitted with load cells. An electrogoniometer was employed to measure hip flexion during the test. Resistive moment at the hip was determined using a dynamic biomechanical model.

RESULTS

The present experimental method was shown to be highly reliable. The moment-angle curves of all subjects were shown to follow an exponential function.

CONCLUSION

Stiffness and strain energy of posterior hip tissues could be derived from the moment-angle curves. Evaluation of such elastic properties is clinically important as they may be altered with injuries of the tissues.

RELEVANCE

Clinically, contracture of hamstring muscles and other posterior hip tissues is evaluated by measuring the available range of hip flexion in straight leg raising. However, this does not provide any information on the elastic properties of the tissues. The present study reports a reliable method of evaluating such properties.

Are dental anomalies risk factors for apical root resorption in orthodontic patients?

Regression analyses suggest a weak prediction power of identified risk factors for apical root resorption in orthodontic patients, indicating the presence of etiologic or causative factors that have not yet been disclosed. To investigate the possible significance of dental anomalies as risk factors, pretreatment and posttreatment periapical radiographs of 84 patients with presence of at least one dental anomaly and of 84 patients without such anomalies were compared. The patients in the two groups were matched according to age, gender, Angle Class, extraction therapy, overbite, and treatment time. Apical root resorption was calculated by subtracting posttreatment tooth length measurements from the corresponding pretreatment measurements. Two sample t tests revealed no differences in mean root resorption between the patients in the two groups (P = .88). Stepwise regression analyses did not identify any of the individual anomalies as risk factors. In addition, patients with more than one anomaly did not appear to be at increased risk.

EAT-4, a homolog of a mammalian sodium-dependent inorganic phosphate cotransporter, is necessary for glutamatergic neurotransmission in caenorhabditis elegans

The Caenorhabditis elegans gene eat-4 affects multiple glutamatergic neurotransmission pathways. We find that eat-4 encodes a protein similar in sequence to a mammalian brain-specific sodium-dependent inorganic phosphate cotransporter I (BNPI). Like BNPI in the rat CNS, eat-4 is expressed predominantly in a specific subset of neurons, including several proposed to be glutamatergic. Loss-of-function mutations in eat-4 cause defective glutamatergic chemical transmission but appear to have little effect on other functions of neurons. Our data suggest that phosphate ions imported into glutamatergic neurons through transporters such as EAT-4 and BNPI are required specifically for glutamatergic neurotransmission.

Mutations in the alpha1 subunit of an L-type voltage-activated Ca2+ channel cause myotonia in Caenorhabditis elegans

The control of excitable cell action potentials is central to animal behavior. We show that the egl-19 gene plays a pivotal role in regulating muscle excitation and contraction in the nematode Caenorhabditis elegans and encodes the alphal subunit of a homologue of vertebrate L-type voltage-activated Ca2+ channels. Semi-dominant, gain-of-function mutations in egl-19 cause myotonia: mutant muscle action potentials are prolonged and the relaxation delayed. Partial loss-of-function mutations cause slow muscle depolarization and feeble contraction. The most severe loss-of-function mutants lack muscle contraction and die as embryos. We localized two myotonic mutations in the sixth membrane-spanning domain of the first repeat (IS6) region, which has been shown to be responsible for voltage-dependent inactivation. A third myotonic mutation implicates IIIS4, a region involved in sensing plasma-membrane voltage change, in the inactivation process.

Compartment-selective sensitivity of cardiovascular morphogenesis to combinations of retinoic acid receptor gene mutations

Several aspects of normal cardiovascular development require signaling by the vitamin A metabolite retinoic acid. We have previously established germ-line mutations in mice in the genes that encode the RAR alpha 1, RAR beta, and RXR alpha retinoic acid receptors as a means of studying the function of these receptors in vivo. Although mutation of RXR alpha results in fetal ventricular defects, the RAR alpha 1 and RAR beta mutations are apparently nonphenotypic in the heart and elsewhere. In this study, we have established and analyzed combinations of these receptor gene mutations. Malformations of the ventricular chamber (chamber hypoplasia and muscular ventricular septal defects), conotruncus (double-outlet right ventricle, transposition, and membranous ventricular septal defects), aortic sac (persistent truncus arteriosus and aorticopulmonary window), and aortic arch-derived arteries were recovered in various combinations of the RAR alpha 1, RAR beta, and RXR alpha gene mutations. Depending on the combination of receptor mutations, selective defects were obtained in specific cardiovascular compartments, suggestive of differential expression or function of each receptor within domains of the developing heart.

The relation of prosocial and antisocial behavior to personality and peer relationships of Hong Kong Chinese adolescents

The prosocial and antisocial behaviors of 2,862 Hong Kong Chinese adolescents were investigated. The major findings were as follows: (a) boys were more antisocial than girls: (b) negative peer influences were significantly stronger in boys than in girls, whereas positive peer influences were significantly stronger in girls than in boys; (c) antisocial adolescents tended to perceive their best friend as antisocial and exerting more negative influences on them, whereas prosocial adolescents tended to perceive their best friend as prosocial and exerting more positive influences on them; (d) antisocial behavior was positively associated with psychoticism and neuroticism; and (e) academic achievement tended to have a positive relation with prosocial behavior and a negative relation with antisocial behavior.

eat-5 and unc-7 represent a multigene family in Caenorhabditis elegans involved in cell-cell coupling

The Drosophila melanogaster genes Passover and l(1)ogre and the Caenorhabditis elegans gene unc-7 define a gene family whose function is not known. We have isolated and characterized the C. elegans gene eat-5, which is required for synchronized pharyngeal muscle contractions, and find that it is a new member of this family. Simultaneous electrical and video recordings reveal that in eat-5 mutants, action potentials of muscles in the anterior and posterior pharynx are unsynchronized. Injection of carboxyfluorescein into muscles of the posterior pharynx demonstrates that all pharyngeal muscles are dye-coupled in wild-type animals; in eat-5 mutants, however, muscles of the anterior pharynx are no longer dye-coupled to posterior pharyngeal muscles. We show that a gene fusion of eat-5 to the green fluorescent protein is expressed in pharyngeal muscles. unc-7 and eat-5 are two of at least sixteen members of this family in C. elegans as determined by database searches and PCR-based screens. The amino acid sequences of five of these members in C. elegans have been deduced from cDNA sequences. Polypeptides of the family are predicted to have four transmembrane domains with cytoplasmic amino and carboxyl termini. We have constructed fusions of one of these polypeptides with beta-galactosidase and with green fluorescent protein. The fusion proteins appear to be localized in a punctate pattern at or near plasma membranes. We speculate that this gene family is required for the formation of gap junctions.

Expression of prokaryotic HhaI DNA methyltransferase is transforming and lethal to NIH 3T3 cells

In neoplastic cells, levels of DNA methyltransferase activity are often increased, and evidence is accruing to suggest an important role for this event in tumorigenesis. To evaluate this possibility further, and to investigate the contribution of increasing de novo, as opposed to maintenance, DNA methylation in mammalian cells, we expressed the bacterial HhaI methyltransferase in cultured murine fibroblasts. This enzyme is a pure de novo DNA methyltransferase that methylates the internal C in the sequence GCGC. We find that both constitutive and induced expression of the wild-type HhaI results, primarily, in lethality to the cells. However, surviving cell clones that express low levels of M. HhaI demonstrate increased tumorigenicity as assessed by soft agar cloning efficiency (8.6% for sense HhaI-transduced PA 317 cells versus 0.4% for antisense controls; 1.7% for sense HhaI-transfected NIH 3T3 cells versus 0% for a mutant HhaI control) and tumorigenicity in nude mouse heterotransplants (75% for sense HhaI-transduced PA 317 cells versus 18.5% for antisense controls). DNA isolated from the clonogenic sense HhaI clones, versus clones expressing the mutant HhaI gene, has no increase in overall CpG methylation but an average of 27% (range, 16.7-38.9) increase in methylcytosine content at GCGC sites. These findings suggest that eukaryotic cells tolerate a narrow window of increase de novo DNA methylating capacity, above which cell death occurs and within cell transformation results. Our results further emphasize the potential role of increased DNA methyltransferase activity in the evolution of cancer.

Detecting alerts, notifying the physician, and offering action items: a comprehensive alerting system

We developed and evaluated a system to automatically identify serious clinical conditions in inpatients. The system notifies the patient's covering physician via his pager that an alert is present and offers potential therapies for the patient's condition (action items) at the time he views the alert information. Over a 6 month period, physicians responded to 1214 (70.2%) of 1730 alerts for which they were paged; they responded to 1002 (82.5% of the 1214) in less than 15 minutes. They said they would take action in 71.5% of the alerts, and they placed an order directly from the alert display screen in 39.4%. Further study is needed to determine if this alerting system improves processes or outcomes of care.

Mutations in the Caenorhabditis elegans Na,K-ATPase alpha-subunit gene, eat-6, disrupt excitable cell function

We have cloned a Na,K-ATPase alpha-subunit gene from Caenorhabditis elegans and discovered that it is identical to the gene eat-6, eat-6 mutations cause feeble contractions and slow, delayed relaxations of pharyngeal muscle. The resting membrane potential of eat-6 mutant pharynxes is consistently depolarized compared to wild-type. The action potentials are smaller, and the return to resting potential is slower. To explain these abnormalities, we propose that a reduction of Na,K-ATPase activity in eat-6 mutants leads to a reduction of the ion concentration gradients that power membrane potential changes.

Interacting genes required for pharyngeal excitation by motor neuron MC in Caenorhabditis elegans

We studied the control of pharyngeal excitation in Caenorhabditis elegans. By laser ablating subsets of the pharyngeal nervous system, we found that the MC neuron type is necessary and probably sufficient for rapid pharyngeal pumping. Electropharyngeograms showed that MC transmits excitatory postsynaptic potentials, suggesting that MC acts as a neurogenic pacemaker for pharyngeal pumping. Mutations in genes required for acetylcholine (ACh) release and an antagonist of the nicotinic ACh receptor (nAChR) reduced pumping rates, suggesting that a nAChR is required for MC transmission. To identify genes required for MC neurotransmission, we screened for mutations that cause slow pumping but no other defects. Mutations in two genes, eat-2 and eat-18, eliminated MC neurotransmission. A gain-of-function eat-18 mutation, ad820sd, and a putative loss-of-function eat-18 mutation, ad1110, both reduced the excitation of pharyngeal muscle in response to the nAChR agonists nicotine and carbachol, suggesting that eat-18 is required for the function of a pharyngeal nAChR. Fourteen recessive mutations in eat-2 fell into five complementation classes. We found allele-specific genetic interactions between eat-2 and eat-18 that correlated with complementation classes of eat-2. We propose that eat-18 and eat-2 function in a multisubunit protein complex involved in the function of a pharyngeal nAChR.

Peptides which bind to E-selectin and block neutrophil adhesion

E-selectin is an inducible cell adhesion molecule which mediates rolling of neutrophils on the endothelium, an early event in the development of an inflammatory response. Inhibition of selectin-mediated rolling is a possible means for controlling inflammation-induced diseases, and several classes of compounds have been tested for this use. We describe here the use of recombinant peptide library screening for identification and optimization of novel ligands which bind to E-selectin. Several of these peptides bind with Kd values in the low nanomolar range and block E-selectin-mediated adhesion of neutrophils in static and flow-cell assays. Administration of the peptide to mice undergoing an acute inflammatory response reduced the extent of neutrophil transmigration to the site of inflammation, demonstrating the utility of this compound as a potential therapeutic. The identification of a peptide ligand for E-selectin suggests that the complete natural ligand for this adhesion molecule may include protein as well as carbohydrate moieties.

Intrarectal tear from water skiing

We report a case of intrarectal tear and hemorrhage after a fall while water skiing. The injury resulted from rectal douche, or jet enema, which is dangerous because of the high pressure of the water jets forced into the rectum. The patient, a middle-aged woman, had colonoscopy, which revealed a deep rectal laceration. During subsequent colostomy, a full-thickness laceration and an extensive pelvic and retroperitoneal hematoma with some free blood were found. The patient's recovery was uneventful, and she subsequently had reanastomosis of her colostomy. We recommend protective apparel to prevent these injuries.

Differential utilization of calcitonin gene regulatory DNA sequences in cultured lines of medullary thyroid carcinoma and small-cell lung carcinoma

Regulation of expression of the human calcitonin gene was found to differ between two tumor lines of different tissue origin, medullary thyroid carcinoma (TT line) and small-cell lung carcinoma (DMS53 line). Distal 5' DNA elements between -750 and -2000 exhibited a stronger basal activity in DMS53 than in TT cells, whereas proximal DNA sequences between -132 and -252 mediated a dramatic cyclic AMP response in TT but not DMS53 cells.

Bacterial chitinase is modified and secreted in transgenic tobacco

The chiA gene of Serratia marcescens codes for a secreted protein, bacterial chitinase (ChiA). We have investigated the modifications and the cellular location of ChiA when it is expressed in transgenic tobacco plants. Immunoblots on total leaf protein probed with antibody to ChiA showed that when the bacterial chitinase is expressed in plants, it migrates as a series of discrete bands with either the same or a slower mobility than the secreted bacterial protein. Analysis of the vacuum infiltrate of leaves expressing ChiA showed that the modified forms of the protein are enriched in the intercellular fluid. Media recovered from suspension cultures of cell lines expressing the chiA gene were also enriched for the modified forms of ChiA. Washed protoplasts, however, contained only the nonmodified form. The molecular weight of these polypeptides is reduced by treatment with glycopeptidase F but not with endoglycosidase H. Treatment of the suspension cultures with tunicamycin also leads to reduction in the molecular weight of the chitinase bands. We suggest that some of the ChiA protein is N-glycosylated and secreted when expressed in plants, and that the modifications are complex glycans. These results show that a bacterial signal sequence can function in plant cells, and that protein secretion from plant cells probably operates by a default pathway.

Chronic intracerebroventricular CRF infusion attenuates ACTH-corticosterone release

Bolus intracerebroventricular delivery of corticotropin-releasing factor (CRF) elicits acute responses of both the pituitary-adrenal axis and the sympathetic nervous system. We examined whether these stresslike responses could be maintained over a period of days by central delivery of CRF in nonstressed rats, as would be predicted if this peptide participates in the central nervous system regulation of chronic stress. CRF (4.3 or 21.5 micrograms/day) was continuously delivered into the cerebral ventricle via Alzet minipumps. In contrast to saline-infused controls, rats receiving CRF exhibited elevated excretions of corticosterone, norepinephrine, and urea nitrogen for several days. Thereafter, an attenuation of CRF responsiveness occurred when corticosterone excretion returned to basal levels despite continued central CRF infusion. However, CRF delivered intravenously during attenuation stimulated adrenocorticotropic hormone and corticosterone secretion, implicating a hypothalamic rather than pituitary locus for central CRF resistance. The present data do not permit a conclusion on whether the attenuation of the CRF response with time is the result of an ultrashort-loop negative-feedback mechanism or CRF receptor desensitization.

Differential physiological and morphological responses of inbred lines to the ethylene precursor 1-aminocyclopropane-1-carboxylic acid by cultured Helianthus annuus (sunflower) shoot tips

The four Helianthus annuus (sunflower) inbred lines examined showed different abilities to convert 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene and different morphological responses to exogenous ACC, however, ACC had no effect on precocious flowering. The greatest effect of ACC was seen with inbred SS405B where it suppressed shoot growth and induced hypocotyl enlargement and callus induction. The greatest response did not correlate with the highest ethylene production. Although each inbred responded differently, callus induction and hypocotyl enlargement observed in hypocotyl segments treated with naphthalene acetic acid and benzyladenine could be partially explained as ethylene-mediated effects of the two hormones. It is suggested that inbred differences could be due to different endogenous hormone levels and/or different sensitivities to them.

Characterization of Acetate and Pyruvate Metabolism in Suspension Cultures of Zea mays by C NMR Spectroscopy

Carbon-13 nuclear magnetic resonance (NMR) spectroscopy has been applied to the direct observation of acetate and pyruvate metabolism in suspension cultures of Zea mays (var Black Mexican Sweet). Growth of the corn cells in the presence of 2 millimolar [2-(13)C]acetate resulted in a rapid uptake of the substrate from the medium and initial labeling (0-4 hours) of primarily the intracellular glutamate and malate pools. Further metabolism of these intermediates resulted in labeling of glutamine, aspartate, and alanine. With [1-(13)C]acetate as the substrate very little incorporation into intermediary metabolites was observed in the (13)C NMR spectra due to loss of the label as (13)CO(2). Uptake of [3-(13)C]pyruvate by the cells was considerably slower than with [2-(13)C]acetate; however, the labelling patterns were similar with the exception of increased [3-(13)C] alanine generation with pyruvate as the substrate. Growth of the cells for up to 96 hours with 2 millimolar [3-(13)C]pyruvate ultimately resulted in labeling of valine, leucine, isoleucine, threonine, and the polyamine putrescine.

Stability of three oral liquid drug products repackaged in unit dose containers

Stability of oral liquid forms of cimetidine hydrochloride, furosemide, and theophylline repackaged in polypropylene oral syringes and glass vials was assessed. Commercial preparations of each product were used; 2-ml quantities were placed in both types of container and stored at 4, 25, 44, 60, and 76 degrees C. Six samples from each container type at each temperature were tested at various times. Stability was defined as no greater than 10% loss of labeled potency. Assay was by high-performance liquid chromatography. All three drugs retained more than 90% of label claim in both types of containers after 180 days at 4 degrees C and 25 degrees C. For cimetidine hydrochloride and furosemide at these temperatures, there was no significant difference in concentration by container type; at the higher storage temperatures, the degradation rate in polypropylene syringes was significantly faster. For theophylline, loss of volume of 10% or greater occurred after 60 days at temperatures greater than 25 degrees C for both container types. Drug loss at higher temperatures was attributed to precipitation of theophylline out of the elixir rather than chemical degradation. Oral liquid cimetidine hydrochloride, furosemide, and theophylline repackaged in either polypropylene oral syringes or glass vials can be stored at 4 degrees C and 25 degrees C for 180 days with less than 10% loss of potency.