Diet-induced obesity does not exacerbate cachexia in male mice bearing Lewis-lung carcinoma tumors

Cachexia is a muscle-wasting syndrome commonly observed in patients with cancer, which can significantly worsen clinical outcomes. Because of a global rise in obesity, the coexistence of cachexia in obese individuals poses unique challenges, with the impact of excessive adiposity on cachexia severity and underlying pathophysiology not well defined. Understanding the interplay between cachexia and obesity is crucial for improving diagnosis and treatment strategies for these patients; therefore, the present study examined differences in cachexia between lean and obese mice bearing Lewis lung carcinoma (LLC) tumors. Nine-week-old, male C57Bl6J mice were placed on either a chow or a high-fat diet (HFD) for 9 wk. After the diet intervention, mice were inoculated with LLC or vehicle. Markers of cachexia, such as body and muscle loss, were noted in both chow and HFD groups with tumors. Tumor weight of HFD animals was greater than that of chow. LLC tumors reduced gastrocnemius, plantaris, and soleus mass, regardless of diet. The tibialis anterior and plantaris mass and cross-sectional area of type IIb/x fibers in the gastrocnemius were not different between HFD-chow, HFD-tumor, and chow-tumor. Using RNA sequencing (RNA-seq) of the plantaris muscle from chow-tumor and HFD-tumor groups, we identified ∼400 differentially expressed genes. Bioinformatic analysis identified changes in lipid metabolism, mitochondria, bioenergetics, and proteasome degradation. Atrophy was not greater despite larger tumor burden in animals fed an HFD, and RNA-seq data suggests that partial protection is mediated through differences in mitochondrial function and protein degradation, which may serve as future mechanistic targets.NEW & NOTEWORTHY This study provides timely information on the interaction between obesity and cancer cachexia. Lean and obese animals show signs of cachexia with reduced body weight, adipose tissue, and gastrocnemius muscle mass. There was not significant wasting in the tibialis anterior, plantaris, or fast twitch fibers in the gastrocnemius muscle of obese animals with tumors. RNA-seq analysis reveals that obese tumor bearing animals had differential expression of mitochondria- and degradation-related genes, which may direct future studies in mechanistic research.

Variable body and tissue weight reporting in preclinical cachexia literature may alter study outcomes and interpretation

Cancer cachexia is a multifactorial syndrome of body weight loss, muscle wasting, and progressive functional decline affecting many advanced cancer patients and leading to worsened clinical outcomes. Despite inherent limitations of many preclinical cachexia models, including large tumor burden, rapid tumor growth, and young age of animals, these animal models are widely used and imperative for the study of cachexia mechanisms and experimental therapeutics. However, there are currently no guidelines for reporting and representation of data in preclinical cachexia literature. We examined the current state of data reporting in publications using the colon-26 adenocarcinoma (C26) model of cachexia and compared statistical differences in reporting mechanisms using animals from our laboratory. We show that data reporting and representation in C26 preclinical cachexia literature is diverse, making comparison of study outcomes difficult. Further, different expression of body and tissue weights in our animals led to differential statistical significance, which could significantly alter data interpretation. This study highlights a need for consistent data reporting in preclinical cancer cachexia literature to effectively compare outcomes between studies and increase translatability to the human condition.

Cancer cachexia: Pathophysiology and association with cancer-related pain

Cachexia is a syndrome of unintentional body weight loss and muscle wasting occurring in 30% of all cancer patients. Patients with cancers most commonly leading to brain metastases have a risk for cachexia development between 20 and 80%. Cachexia causes severe weakness and fatigue and negatively impacts quality and length of life. The negative energy balance in cachectic patients is most often caused by a combination of increased energy expenditure and decreased energy intake. Basal metabolic rate may be elevated due to tumor secreted factors and a systemic inflammatory response leading to inefficiency in energy production pathways and increased energy demand by the tumor and host tissues. A growing body of research explores physiological and molecular mechanisms of metabolic dysregulation in cachexia. However, decreased energy intake and physical functioning also remain important contributors to cachexia pathogenesis. Pain associated with metastatic malignancy is significantly associated with inflammation, thus making inflammation a common link between cancer pain and cachexia. Pain may also influence appetite and food intake and exacerbate fatigue and functional decline, potentially contributing to cachexia severity. Cancer pain and cachexia often occur simultaneously; however, causal relationships remain to be established. Appropriate assessment and treatment of pain in advanced cancer patients may positively impact nutrition status and physical functioning, slowing the progression of cachexia and improving quality and length of life for patients.

Leucine Supplementation in Cancer Cachexia: Mechanisms and a Review of the Pre-Clinical Literature

Cancer cachexia (CC) is a complex syndrome of bodily wasting and progressive functional decline. Unlike starvation, cachexia cannot be reversed by increased energy intake alone. Nonetheless, targeted nutritional support is a necessary component in multimodal syndrome management. Due to the highly catabolic nature of cancer cachexia, amino acid supplementation has been proposed. Interestingly, leucine has been found to increase protein synthesis and decrease protein degradation via mTORC1 pathway activation. Multiple pre-clinical studies have explored the impact of leucine supplementation in cachectic tumor-bearing hosts. Here, we provide an overview of leucine’s proposed modes of action to preserve lean mass in cachexia and review the current pre-clinical literature related to leucine supplementation during CC. Current research indicates that a leucine-rich diet may attenuate CC symptomology; however, these works are difficult to compare due to methodological differences. There is need for further pre-clinical work exploring leucine’s potential ability to modulate protein turnover and immune response during CC, as well as the impact of additive leucine on tumor growth.

Cardiac Remodeling in Cancer-Induced Cachexia: Functional, Structural, and Metabolic Contributors

Cancer cachexia is a syndrome of progressive weight loss and muscle wasting occurring in many advanced cancer patients. Cachexia significantly impairs quality of life and increases mortality. Cardiac atrophy and dysfunction have been observed in patients with cachexia, which may contribute to cachexia pathophysiology. However, relative to skeletal muscle, little research has been carried out to understand the mechanisms of cardiomyopathy in cachexia. Here, we review what is known clinically about the cardiac changes occurring in cachexia, followed by further discussion of underlying physiological and molecular mechanisms contributing to cachexia-induced cardiomyopathy. Impaired cardiac contractility and relaxation may be explained by a complex interplay of significant heart muscle atrophy and metabolic remodeling, including mitochondrial dysfunction. Because cardiac muscle has fundamental differences compared to skeletal muscle, understanding cardiac-specific effects of cachexia may bring light to unique therapeutic targets and ultimately improve clinical management for patients with cancer cachexia.

Social stress is lethal in the mdx model of Duchenne muscular dystrophy

Background

Duchenne muscular dystrophy (DMD) is caused by the loss of dystrophin. Severe and ultimately lethal, DMD progresses relatively slowly in that patients become wheelchair bound only around age twelve with a survival expectancy reaching the third decade of life.

Methods

The mildly-affected mdx mouse model of DMD, and transgenic DysΔMTB-mdx and Fiona-mdx mice expressing dystrophin or utrophin, respectively, were exposed to either mild (scruffing) or severe (subordination stress) stress paradigms and profiled for their behavioral and physiological responses. A subgroup of mdx mice exposed to subordination stress were pretreated with the beta-blocker metoprolol.

Findings

Subordination stress caused lethality in ∼30% of mdx mice within 24 h and ∼70% lethality within 48 h, which was not rescued by metoprolol. Lethality was associated with heart damage, waddling gait and hypo-locomotion, as well as marked up-regulation of the hypothalamus-pituitary-adrenocortical axis. A novel cardiovascular phenotype emerged in mdx mice, in that scruffing caused a transient drop in arterial pressure, while subordination stress caused severe and sustained hypotension with concurrent tachycardia. Transgenic expression of dystrophin or utrophin in skeletal muscle protected mdx mice from scruffing and social stress-induced responses including mortality.

Interpretation

We have identified a robust new stress phenotype in the otherwise mildly affected mdx mouse that suggests relatively benign handling may impact the outcome of behavioural experiments, but which should also expedite the knowledge-based therapy development for DMD.

Funding

Greg Marzolf Jr. Foundation, Summer's Wish Fund, NIAMS, Muscular Dystrophy Association, University of Minnesota and John and Cheri Gunvalson Trust.

Dysregulation of Calcium Handling in Duchenne Muscular Dystrophy-Associated Dilated Cardiomyopathy: Mechanisms and Experimental Therapeutic Strategies

: Duchenne muscular dystrophy (DMD) is an X-linked recessive disease resulting in the loss of dystrophin, a key cytoskeletal protein in the dystrophin-glycoprotein complex. Dystrophin connects the extracellular matrix with the cytoskeleton and stabilizes the sarcolemma. Cardiomyopathy is prominent in adolescents and young adults with DMD, manifesting as dilated cardiomyopathy (DCM) in the later stages of disease. Sarcolemmal instability, leading to calcium mishandling and overload in the cardiac myocyte, is a key mechanistic contributor to muscle cell death, fibrosis, and diminished cardiac contractile function in DMD patients. Current therapies for DMD cardiomyopathy can slow disease progression, but they do not directly target aberrant calcium handling and calcium overload. Experimental therapeutic targets that address calcium mishandling and overload include membrane stabilization, inhibition of stretch-activated channels, ryanodine receptor stabilization, and augmentation of calcium cycling via modulation of the Serca2a/phospholamban (PLN) complex or cytosolic calcium buffering. This paper addresses what is known about the mechanistic basis of calcium mishandling in DCM, with a focus on DMD cardiomyopathy. Additionally, we discuss currently utilized therapies for DMD cardiomyopathy, and review experimental therapeutic strategies targeting the calcium handling defects in DCM and DMD cardiomyopathy.

Exacerbation of dystrophic cardiomyopathy by phospholamban deficiency mediated chronically increased cardiac Ca2+ cycling in vivo

Cardiomyopathy is a significant contributor to morbidity and mortality in Duchenne muscular dystrophy (DMD). Membrane instability, leading to intracellular Ca²⁺ mishandling and overload, causes myocyte death and subsequent fibrosis in DMD cardiomyopathy. On a cellular level, cardiac myocytes from mdx mice have dysregulated Ca²⁺ handling, including increased resting Ca²⁺ and slow Ca²⁺ decay, especially evident under stress conditions. Sarco(endo)plasmic reticulum Ca²⁺ ATPase and its regulatory protein phospholamban (PLN) are potential therapeutic targets for DMD cardiomyopathy owing to their key role in regulating intracellular Ca²⁺ cycling. We tested the hypothesis that enhanced cardiac Ca²⁺ cycling would remediate cardiomyopathy caused by dystrophin deficiency. We used a genetic complementation model approach by crossing dystrophin-deficient mdx mice with PLN knockout (PLNKO) mice [termed double-knockout (DKO) mice]. As expected, adult cardiac myocytes isolated from DKO mice exhibited increased contractility and faster relaxation associated with increased Ca²⁺ transient peak height and faster Ca²⁺ decay rate compared with control mice. However, compared with wild-type, mdx, and PLNKO mice, DKO mice unexpectedly had reduced in vivo systolic and diastolic function as measured by echocardiography. Furthermore, Evans blue dye uptake was increased in DKO hearts compared with control, mdx, and PLNKO hearts, demonstrating increased membrane damage, which subsequently led to increased fibrosis in the DKO myocardium in vivo. In conclusion, despite enhanced intracellular Ca²⁺ handling at the myocyte level, DMD cardiomyopathy was exacerbated owing to unregulated chronic increases in Ca²⁺ cycling in DKO mice in vivo. These findings have potentially important implications for ongoing therapeutic strategies for the dystrophic heart. NEW & NOTEWORTHY This study examined the effects of phospholamban ablation on the pathophysiology of cardiomyopathy in dystrophin-deficient mice. In this setting, contractility and Ca²⁺ cycling were enhanced in isolated myocytes; however, in vivo heart function was diminished. Additionally, sarcolemmal integrity was compromised and fibrosis was increased. This is the first study, to our knowledge, examining unregulated Ca²⁺ cycling in the dystrophin-deficient heart. Results from this study have implications for potential therapies targeting Ca²⁺ handling in dystrophic cardiomyopathy. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/unregulated-ca2-cycling-exacerbates-dmd-cardiomyopathy/ .

Simultaneous determination of key bioactive components in Hedyotis diffusa by capillary electrophoresis

A capillary zone electrophoresis (CZE) method based on systematic one-variable-at-a time approach was developed for the analysis of four important bioactive components (geniposidic acid, ursolic acid, quercetin and p-coumaric acid) in the extract of Hedyotis diffusa (HD). Separations were carried out in a fused-silica capillary tube with peak detection at 214 nm. Good separation was achieved using a 20 mM borate buffer containing 5% acetonitrile as organic modifier and pH adjusted to 10.0. Operating voltage was 15 kV and temperature was maintained at 25 degrees C while hydrodynamic injection was 5s. A good linearity, with correlation coefficients in the ranges of 0.997-0.999 was obtained in the calibration curves of each standard. Relative standard deviation (R.S.D.) of migration time was between 0.32 and 0.70% and deviation of corrected peak area was between 8.84 and 11.99%. These results indicate that this method could be used for rapid and simultaneous analysis of the bioactive components in HD and other herbal products.

Managing quality of teaching and learning in the ophthalmic nursing course

With auditing of teaching and learning in earnest by the Quality Assurance Agency for the Higher Education Funding Council, the nature of quality in education is top on the agenda for educational stakeholders. However, the nature of quality is difficult to define and measure. This is because quality is essentially a subjective perception and can mean different things to different individuals. Therefore, attempt to quantify and measure quality is difficult and problematic but is necessary for personal, professional, bureaucratic, political and stakeholder demands for accountability, and demonstration of efficiency, effectiveness and value for money. Using a total quality management framework, the internal controls of quality in the ophthalmic nursing course and at the faculty level are considered. The wider contexts of quality control from the institutional, political and at the customer's levels are explored. This paper concludes that the various methods used to control and measure quality may provide useful information for service clarity and a basis for service development. However, such information needs to be treated with caution and interpreted in the context and environment in which this information is generated. Ultimately, the issues of quality in teaching and learning may be addressed by the teacher's commitment to be developed as a reflective practitioner.

A telephone survey of day-surgery eye patients

The objective of this research study was to evaluate the nursing care processes and patient satisfaction with the new day-surgery services. Forty-five adult day-surgery eye patients were selected at random to take part in a telephone survey. The response rate was 84.4% (38). Patients were contacted 48 hours post-surgery to obtain their view of the entire surgical experience. The research result found that the majority of the patients were satisfied with the day-surgery services. The main problems experienced by patients were long waiting times to see the doctor during pre-operation assessment, unsatisfactory journeys to and from theatre, and difficulty in remembering verbal advice. Twenty-eight (73.6%) of the day-surgery patients would prefer day-surgery again for a similar operation, but 10 (26.3%) would prefer a longer stay in hospital. The main implications for practice are that realistic assessment time should be allocated to reduce waiting time, verbal advice should be accompanied by written leaflets or audio-tape, and patients should be encouraged to make an informed choice about day or in-patient surgery. A regular survey of day-surgery eye patients should be part of a general audit.

Determination of methamidophos residues in food remnants

Over the past 7 years, acute food poisoning arising from the consumption of methamidophos-tainted vegetables has occurred sporadically in Hong Kong. To enable prompt remedial and regulatory actions to be taken, a simple and rapid gas chromatographic method was developed to determine methamidophos residues in food remnants. Samples were homogenized and extracted with acetone. Acetone in the resultant extract was removed by rotary evaporation, leaving behind an aqueous solution. After washing with petroleum ether and addition of sodium sulphate, the aqueous solution was re-extracted with chloroform. The chloroform extract was concentrated to dryness and the residue was reconstituted in absolute ethanol for determination by gas chromatography with flame photometric detection. The method was found to be applicable also to the determination of acephate, dimethoate, omethoate and trichlorfon. Mean recoveries of the five organo-phosphorus pesticides at two fortification levels, viz. 1 mg/kg and 10 mg/kg, ranged from 74 to 113%. Relative standard deviations lay between 1.3 and 6.1%. Method detection limits ranged from 0.02 to 0.04 mg/kg. In 1994, 75 food poisoning cases in Hong Kong were suspected to be related to the consumption of methamidophos-tainted vegetables; 13 food remnants were received for analysis, four of them were found to contain high concentrations of methamidophos.

The gene for the alpha 2 chain of the human fibrillar collagen type XI (COL11A2) assigned to the short arm of chromosome 6

A cosmid clone (CosHcol.11) containing the alpha 2(XI) collagen gene (COL11A2) has been isolated. The gene contains conserved DNA and amino-acid sequences characteristic of fibril forming collagen, which is in accordance with the classification of type XI collagen as a fibrillar collagen. The genomic clone containing the alpha 2(XI) gene has been used as probe in the Southern blot analysis of DNA from a panel of human/hamster somatic cell hybrids containing different numbers and combinations of human chromosomes. Synteny analysis revealed that only chromosome 6 showed complete concordant segregation with COL11A2. Furthermore, the gene was regionally mapped to the short arm of chromosome 6 by using a hybrid which contained only the long arm of the chromosome.

A nuclear protein associated with human cancer cells binds preferentially to a human repetitive DNA sequence

A protein (Rp66) of 66 kDa was shown by DNA-binding protein blot assay to bind to a human repetitive DNA sequence (low-repeat sequence; LRS) in each of 10 transformed human cell lines examined. This protein-DNA interaction was not observed in 11 normal human cell cultures or in the Chinese hamster cell line CHO-K1. Gel retardation assay confirmed the specificity of the protein-DNA binding between Rp66 and LRS. In a histiocytic lymphoma human cell line, U937, that can be induced to differentiate in the presence of phorbol ester, this binding disappeared after cell differentiation. These together with other results cited suggest a regulatory role for these repetitive sequences in the human genome, with particular application to cancer.

Isolation and chromosomal localization of the human En-2 gene

By low stringency hybridization we have isolated from a human cosmid genomic library sequences homologous with a probe from the Drosophila engrailed gene. Partial nucleotide sequence analysis shows a consensus splice acceptor site followed by an open reading frame (ORF) that can encode 104 amino acids; the first 94 amino acids have 71% identity with the Drosophila engrailed protein. The shared region contains a homeo domain and is within the region of engrailed shared with the Drosophila invected gene and the mouse En-1 and En-2 genes. At the amino acid level, the human sequence is 85% identical with the mouse En-1 gene and 100% identical with the mouse En-2 gene. Hybridization against a panel of human-hamster somatic cell hybrids maps this human En-2 gene to chromosome 7, and regional mapping by in situ hybridization to human chromosomes localizes it to region 7q36 at the end of the long arm.

Chromosomal localization of the human gene for brain Ca2+/calmodulin-dependent protein kinase type IV

Cloned cDNAs have been identified as corresponding to a new brain Ca2+/calmodulin-dependent protein kinase. On the basis of structural and immunological features, we refer to this new kinase as CaM Kinase IV. Two cDNA clones were used to identify CaM Kinase IV: The downstream clone, lambda ICM-1, contains the sequence encoding the calmodulin-binding site and the second clone, lambda ICM-2, encodes a partial amino acid sequence similar to the catalytic domain of several known protein kinases. Within the calmodulin-binding site a stretch of 8 amino acids (and 9 of 10) is identical to the corresponding site in the subunits of CaM Kinase II. Southern blot analysis shows the CaM Kinase IV gene is single copy in the mouse and human genomes. Synteny analysis of Southern blot data of DNA from hamster--human hybrid cells shows that the gene is present in human chromosome 5. Hybridization of cDNA probes to metaphase spreads of human chromosomes indicates that the gene is most likely located within the region of bands q21 to q23 of chromosome 5.

Assignment of human gene encoding testis-specific lactate dehydrogenase C to chromosome 11, region p14.3-p15.5

The human gene coding for lactate dehydrogenase C (LDHC), a testis-specific isozyme, has been assigned to a refined region of chromosome 11, p14.3-p15.5, in which the lactate dehydrogenase A gene (LDHA) also resides, by using somatic cell hybrids and in situ chromosome hybridization. This assignment clearly indicates the close physical proximity of the LDHC and LDHA genes and supports the evolutionary closeness of these two isozymes.

The GLI-Kruppel family of human genes

Previous characterization of GLI, a gene found to be amplified and expressed in a subset of human brain tumors, revealed the presence of five tandem zinc fingers related to those of Krüppel (Kr), a Drosophila segmentation gene of the gap class. We have used the GLI cDNA as a molecular probe to isolate related sequences from the human genome. Partial characterization of six related loci, including sequence determination, expression studies, and chromosome localization, revealed that each locus could encode a separate finger protein. The predicted proteins all had similar H-C links, i.e., a conserved stretch of 9 amino acids connecting the C-terminal histidine of one finger to the N-terminal cysteine of the next. On the basis of amino acid sequence and intron-exon organization, the genes could be placed into one of two subgroups: the GLI subgroup (with the consensus finger amino acid sequence [Y/F]XCX3GCX3[F/Y]X5LX2HX3-4H[T/S]GEKP) or the Kr subgroup (with the consensus finger amino acid sequence [Y/F]XCX2CX3FX5LX2HXRXHTGEKP). Unlike GLI or Kr, most of the newly isolated genes were expressed in many adult tissues. The predicted proteins probably control the expression of other genes and, by analogy with Kr and GLI, may be important in human development, tissue-specific differentiation, or neoplasia.

The hemopexin gene maps to the same location as the beta-globin gene cluster on human chromosome 11

Using human hemopexin cDNA clones isolated from lambda gt11 cDNA library as probes, we have carried out Southern blot analysis of a series of human-Chinese hamster somatic cell hybrids containing different combinations of human chromosomes. Synteny analysis revealed 100% concordance between the hemopexin gene and human chromosome 11. In situ hybridization of 3H-labeled hemopexin cDNA to metaphase chromosomes prepared from human lymphocytes further localized the gene to the region p15.4-p15.5, the same location as the beta-globin gene cluster.

Human placental Na+,K+-ATPase alpha subunit: cDNA cloning, tissue expression, DNA polymorphism, and chromosomal localization

A 2.2-kilobase clone comprising a major portion of the coding sequence of the Na+,K+-ATPase alpha subunit was cloned from human placenta and its sequence was identical to that encoding the alpha subunit of human kidney and HeLa cells. Transfer blot analysis of the mRNA products of the Na+,K+-ATPase gene from various human tissues and cell lines revealed only one band (approximately 4.7 kilobases) under low and high stringency washing conditions. The levels of expression in the tissues were intestine greater than placenta greater than liver greater than pancreas, and in the cell lines the levels were human erythroleukemia greater than butyrate-induced colon greater than colon greater than brain greater than HeLa cells. mRNA was undetectable in reticulocytes, consistent with our failure to detect positive clones in a size-selected (greater than 2 kilobases) lambda gt11 reticulocyte cDNA library. DNA analysis revealed a polymorphic EcoRI band and chromosome localization by flow sorting and in situ hybridization showed that the alpha subunit is on the short arm (band p11-p13) of chromosome 1.

Regional localization of the gene coding for sphingolipid activator protein SAP-1 on human chromosome 10

Sphingolipid activator protein SAP-1 is required for the enzymatic hydrolysis of GMI ganglioside and sulfatide. The gene coding for SAP-1 was previously mapped to human chromosome 10 using monospecific antibodies prepared against SAP-1 in synteny analysis of somatic cell hybrids. In this study, we used a cDNA probe for SAP-1 and in situ hybridization to regionally localize the SAP1 gene to the long arm of chromosome 10, region q21-22. Additional mapping data using cell hybrids containing partial chromosome 10 and skin fibroblasts with trisomy 10p are consistent with the in situ hybridization mapping results.

Confirmation of assignment of the human alpha 1-crystallin gene (CRYA1) to chromosome 21 with regional localization to q22.3

The crystallins are highly conserved structural proteins universally found in the eye lens of all vertebrate species. In mammals, three immunologically distinct classes are present, alpha-, beta-, and gamma-crystallins, and each class represents a multigene family. The alpha-crystallin gene family consists of alpha 1-crystallin (CRYA1) and alpha 2-crystallin (CRYA2) genes (previously designated alpha A- and alpha B-crystallin, respectively), which show extensive sequence homology. We constructed a synthetic oligonucleotide probe of 25 bases corresponding to a specific region of the human alpha 1-crystallin gene sequence. This 25-mer probe bears little sequence homology to human alpha 2-crystallin gene and does not cross-hybridize to alpha 2-crystallin sequences in Southern blot analysis. Using this unique synthetic probe, we have demonstrated the identity of the alpha 1-crystallin gene in human genomic DNA. In addition, we have also confirmed its chromosomal location on human chromosome 21. Finally, we have regionally localized the gene to q22.3 by using both Southern blot analysis of a panel of cell hybrids containing different parts of human chromosome 21, and in situ hybridization to metaphase chromosomes. The use of synthetic oligonucleotide probes specific for individual genes should be useful in identifying and mapping members of multigene families.

The progesterone receptor gene maps to human chromosome band 11q13, the site of the mammary oncogene int-2

Progesterone is involved in the development and progression of breast cancers, and progesterone receptors (PR) are important markers of hormone dependence and disease prognosis. We have used a human PR cDNA probe, genomic DNA blotting of a series of Chinese hamster-human cell hybrids, and in situ hybridization to map the human PR gene to chromosome 11, band q13. This band also contains the human homolog of the mouse mammary tumor virus integration site, int-2, which surrounds a protooncogene thought to be involved in the development of murine mammary cancers. That these two genes share the same chromosomal location raises important questions about their possible linkage and about the relationship between the mammary-specific oncogene and the steroid hormone in the development, growth, and hormone dependence of human breast cancers.

Identification of an amplified, highly expressed gene in a human glioma

A gene, termed gli, was identified that is amplified more than 50-fold in a malignant glioma. The gene is expressed at high levels in the original tumor and its derived cell line and is located at chromosome 12 position (q13 to q14.3). The gli gene is a member of a select group of cellular genes that are genetically altered in primary human tumors.

Primate evolution of a dispersed human repetitive DNA sequence

A dispersed middle repetitive DNA sequence isolated originally from human chromosome 12 did not show homology with rodent DNA under standard conditions of Southern DNA blot analysis. The evolutionary relationship of this human repetitive DNA to that of other primates was investigated using three hybridization methods: DNA dot blot, Southern DNA blot analysis, and chromosome in situ hybridization. Homology with the human repetitive DNA was found throughout the suborder Anthropoidea, in fourteen ape and New and Old World monkey species. In addition, the human pattern of hybridization to noncentromeric regions of all chromosomes was seen. No hybridization by any of the three techniques was found in five species of the suborder Prosimii. The phenomenon of marked differences in sequence homology and copy number of dispersed repetitive DNA from closely related species has been observed in protozoans (Plasmodia), Drosophila, sea urchins, mice and the great apes (Hominoidea). We report here a similar phenomenon that may have occurred at an early stage in primate evolution.

DNA microextraction from dried blood spots on filter paper blotters: potential applications to newborn screening

Microextraction of DNA from dried blood specimens would ease specimen transport to centralized laboratory facilities for recombinant DNA diagnosis in the same manner as use of dried blood spots allowed the broad application of screening tests to newborn populations. A method is described which reproducibly yields 0.5 microgram DNA from the dried equivalent of 50 microliters whole blood. Though DNA yields decreased with storage of dried specimens at room temperature, good-quality DNA was still obtained. Sufficient DNA was routinely obtained for Southern blot analysis using repetitive and unique sequences. This microextraction procedure will allow immediate application of molecular genetic technology to direct newborn screening follow-up of disorders amenable to DNA diagnosis, such as sickle cell anemia, and may eventually permit primary DNA screening for specific mutations.

Activity of DNA and RNA polymerases in resurfacing rabbit corneal epithelium

Activity of RNA polymerases I, II and III (distinguished using alpha-amanitin) and activity of DNA polymerases alpha and beta (distinguished using N-ethylmaleimide) were assayed for varying intervals and at varying substrate (UTP or dTTP) concentrations in the purified nuclear fraction from corneal epithelium of carbamylcholine-treated and control eyes of rabbits with resurfacing acid burn defects. Incorporation was linear with time for all enzymes up to 30 min. In 10 min assays at varying substrate concentrations, all polymerases from carbamylcholine-treated eyes had significantly elevated Vmax compared to corresponding control enzymes. The drug also increased apparent affinity of RNA polymerase II for UTP and apparent affinity of DNA polymerases alpha and beta for dTTP. Results are discussed in relation to potential mechanisms by which effects of carbamylcholine on polymerase activity may be mediated.

Application of molecular and somatic cell genetics to the study of chromosome 21

An extra copy of human chromosome 21 has been known for over twenty years to be the chromosomal abnormality in Down's syndrome; however, the biochemical and molecular basis governing expression of the phenotype is still poorly understood. Using the methods of somatic cell and molecular genetics, we have been studying genes and DNA sequences on chromosome 21 by constructing hamster/human hybrids containing a whole or partial chromosome 21 and assigning their locations on the chromosome. In particular, a family of repetitive sequences, some having only a few thousand copies in the human genome, have been used as cloned DNA markers to define deletions in these somatic cell hybrids. We have shown that this approach can significantly improve the resolution of fine chromosomal structures over the conventional cytogenetic analysis. The rationale behind this approach is the observation that a repetitive sequence probe often forms multiple bands after hybridizing to a Southern blot of digested hybrid DNA, and the band pattern appears to be unique for each human chromosome. Therefore, each band (sequence) can be assigned to a particular region of human chromosome 21 by comparing the band patterns from hybrids containing different portions of the chromosome. Results presented here showed that a 0.58-kb repetitive sequence probe can be used to identify deletions, translocations, and other more complicated rearrangements of chromosome 21 seen in patients with abnormalities of this chromosome. The advantage of using such a repetitive sequence probe over a unique sequence is that it can serve both as a repetitive sequence defining multiple sites (multiple bands on a Southern blot) in the genome and at the same time serve as a unique sequence defining a particular site (individual band). For the detection of deletions and other rearrangements, especially in small chromosomes such as 21, it is the former property that makes it very efficient in the initial assignment of a chromosome location.

The gene for the major intrinsic protein (MIP) of the ocular lens is assigned to human chromosome 12cen-q14

The gene for the human major intrinsic protein (MIP) of the ocular lens fiber membrane has been assigned to region cen-q14 of chromosome 12 through the use of somatic cell hybrids containing the whole chromosome and parts of human chromosome 12.

Chromosomal assignment of the human erythropoietin gene and its DNA polymorphism

Erythropoietin (EPO), a glycoprotein hormone, is the major physiological regulator of erythrocyte production in mammals. A cDNA clone containing the entire human EPO-coding region was used for Southern blot analysis of a series of human-Chinese hamster somatic cell hybrids containing different combinations of human chromosomes. Synteny analysis revealed 100% concordance between the EPO gene and human chromosome 7. Further localization to the region q11-q22 was accomplished by in situ hybridization of 3H-labeled human EPO cDNA to metaphase chromosomes prepared from both human lymphocytes and the cell hybrid 879-2a that contained human chromosomes 5, 7, 9, 12, and 21. In addition, restriction fragment length polymorphisms were detected at a frequency of approximately 20% in a Chinese population using restriction enzymes either HindIII or HinfI. These polymorphisms were inherited in a Mendelian fashion. Thus, the EPO marker is reasonably polymorphic and should be useful in linkage analysis with other genetic markers on chromosome 7, including the locus for cystic fibrosis.

The human type II collagen gene (COL2A1) assigned to 12q14.3

A cosmid clone containing the entire human type II alpha 1 collagen gene (COL2A1) was used as probe in the Southern analysis of DNA from a panel of human/hamster somatic cell hybrids containing different portions of human chromosome 12. Two of the hybrids exhibited a similar terminal deletion q14.3----qter, but one was positive for the gene while the other was negative. Therefore, the gene must reside in the region q14.3.

Identification of 200,000-dalton human cell surface protein encoded by gene mapped to long arm of chromosome 11

Cell surface proteins and glycoproteins of human and Chinese hamster cells and their hybrid cell clones were analyzed by two-dimensional gel electrophoresis. The J1 clone of human-Chinese hamster hybrid cells contained chromosome 11 as its only human chromosome. The J1 cells expressed a glycoprotein of 200,000 daltons which was shared by human fibroblasts but not by the parental Chinese hamster ovary cells. The 200,000-dalton protein was identified as a cell surface protein by the method of lactoperoxidase-catalyzed iodination. The protein was electrophoretically purified from radioiodinated cultures of human fibroblasts and J1 cells and subjected to the analysis of tryptic peptides by thin-layer electrophoresis followed by chromatography. The protein from both sources gave rise to fingerprints which closely resembled to each other. The results are consistent with a hypothesis that the 200,000-dalton protein of the J1 clone is of human origin. Analysis of segregant clones of J1 cells, which have deletions on human chromosome 11, has further suggested that the gene for this glycoprotein maps to the long arm of chromosome 11. A gene coding for the 200,000-dalton protein has not been previously mapped to this chromosome.

Localization of a beta-crystallin gene, Hu beta A3/A1 (gene symbol: CRYB1), to the long arm of human chromosome 17

We have assigned a human beta-crystallin gene, Hu beta A3/A1 (gene symbol: CRYB1), to chromosome 17 using a panel of 19 human-hamster somatic cell hybrids and blot-hybridization analysis of cell hybrid DNA. Positive probe-hybridization signal was detected in a hybrid that had lost the short arm of human chromosome 17 but retained the long arm, translocated to a hamster chromosome. In addition, in situ hybridization analysis of metaphase chromosome spreads of this cell line suggested that the most probable location for CRYB1 is on the long arm of chromosome 17, in the region q21.

Cyclic nucleotides in muscarinic regulation of DNA and RNA polymerase activity in cultured corneal epithelial cells of the rabbit

DNA and RNA polymerase activities in the purified nuclear fraction from cultured rabbit corneal epithelial cells were assayed over a range of substrate (labeled dTTP or UTP) concentrations using calf thymus DNA as template. Effects of carbamylcholine on polymerase activities were evaluated over a range of drug concentrations including those saturating muscarinic receptors. Carbamylcholine significantly (p less than 0.001) enhanced activity of both polymerases, both in nuclei incubated with the drug during assay and in nuclei from carbamylcholine-treated cells. Drug effects were blocked by atropine. Regression analysis of Hill plots for variation of polymerase activity with carbamylcholine concentration indicated half-maximal activity of both polymerases at approximately 1 microM carbamylcholine. Mechanisms by which carbamylcholine may alter polymerase activities are discussed in relation to effects of the drug on nuclear enzymes of cyclic nucleotide metabolism and on cyclic nucleotide-dependent protein phosphorylation.

Regional mapping of the phenylalanine hydroxylase gene and the phenylketonuria locus in the human genome

Phenylketonuria (PKU) is an autosomal recessive disorder of amino acid metabolism caused by a deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH; phenylalanine 4-monooxygenase, EC 1.14.16.1). A cDNA clone for human PAH has previously been used to assign the corresponding gene to human chromosome 12. To define the regional map position of the disease locus and the PAH gene on human chromosome 12, DNA was isolated from human-hamster somatic cell hybrids with various deletions of human chromosome 12 and was analyzed by Southern blot analysis using the human cDNA PAH clone as a hybridization probe. From these results, together with detailed biochemical and cytogenetic characterization of the hybrid cells, the region on chromosome 12 containing the human PAH gene has been defined as 12q14.3----qter. The PAH map position on chromosome 12 was further localized by in situ hybridization of 125I-labeled human PAH cDNA to chromosomes prepared from a human lymphoblastoid cell line. Results of these experiments demonstrated that the region on chromosome 12 containing the PAH gene and the PKU locus in man is 12q22----12q24.1. These results not only provide a regionalized map position for a major human disease locus but also can serve as a reference point for linkage analysis with other DNA markers on human chromosome 12.

The gene coding for a sphingolipid activator protein, SAP-1, is on human chromosome 10

SAP-1 is a sphingolipid activator protein found in human tissues required for the enzymatic hydrolysis of GM1 ganglioside and sulfatide. It appears to be missing in patients who have a genetic lipidosis resembling juvenile metachromatic leukodystrophy. Using rabbit antibodies against human SAP-1 it could be visualized in extracts from cultured human skin fibroblasts after sodium dodecylsulfate-polyacrylamide gel electrophoresis, followed by electroblotting to nitrocellulose membrane and immunochemical staining (Western blotting). A series of 23 human-Chinese hamster ovary cell hybrids containing different human chromosomes were examined. The parent Chinese hamster ovary cells did not have a reacting protein in the region of human SAP-1. Only in the eight hybrid clones containing human chromosome 10 was a reacting protein identified. Other chromosomes were excluded by this method. Therefore the gene for SAP-1 and the genetic mutation resulting in a fatal lipidosis are located on human chromosome 10.

Chromosome deletion mapping of interspersed low-copy repetitive DNA

A cloned 2.2 Eco RI segment of interspersed repetitive DNA was hybridized to genomic DNA from a mentally retarded patient with an interstitial deletion in the long arm of one chromosome 12 (12q-). Under hybridization conditions of high stringency, one prominent 2.2-kilobase (kb) Eco RI fragment demonstrated reduced autoradiographic intensity in the 12q- sample compared with several normal controls. These findings indicate that the genomic location for one of the highly or perfectly homologous 2.2-kb Eco RI fragments is in chromosome region 12q21q22, and suggest that a low-copy repetitive DNA probe as used here may have practical utility, as in detecting small deletions or other chromosome alterations.

Genetic mapping of the structural gene for antithrombin III to human chromosome 1

Using a purified cDNA probe of human antithrombin III (AT3) gene and a series of human/Chinese hamster cell hybrids, we established the chromosomal location of the structural gene for AT3 in human chromosome 1 by Southern blot analysis.

Regional localization of two human cellular Kirsten ras genes on chromosomes 6 and 12

Human cellular Kirsten ras1 and ras2 genes were localized to chromosomes 6p23 ----q12 and 12p12 .05----pter, respectively, using human-rodent cell hybrids. Thus, the short arms of human chromosomes 11 (encoding lactate dehydrogenase-A and the proto-oncogene c-Ha- ras1 ) and 12 (encoding lactate dehydrogenase B and c-Ki- ras2 ) share at least two pairs of genes that probably evolved from common ancestral genes.

Localization of the structural gene for human apolipoprotein A-I on the long arm of human chromosome 11

Apolipoprotein A-I (apo A-I), the major apolipoprotein in human high density lipoproteins, is involved in the disease atherosclerosis. Cloned apo A-I cDNA (pA1-3) was used as a probe in chromosome mapping studies to detect the human apo A-I structural gene sequence in human-Chinese hamster cell hybrids. Southern blot analysis of 13 hybrids localized the gene to human chromosome 11. Confirmation of the chromosomal assignment was obtained by analysis of a hybrid (J1) containing a single human chromosome, no. 11. Regional mapping was achieved by using deletion subclones of J1 that localized the human apo A-I structural gene to the region 11q13 leads to qter. Since the human apolipoprotein C-III (apo C-III) structural gene is closely linked to apo A-I, it can be assigned to the same region on the long arm of chromosome 11. By extension of methods previously described, it now appears possible to carry out fine-structure analysis of this and related gene regions on chromosome 11 and to study the biochemical concomitants of these genes and of genes on other chromosomes for analysis of their role in atherosclerosis.

Assignment of the alpha 1-antitrypsin gene and a sequence-related gene to human chromosome 14 by molecular hybridization

alpha 1-Antitrypsin is a major plasma protease inhibitor synthesized in the liver. Genetic deficiency of this protein predisposes the affected individuals to development of infantile liver cirrhosis or chronic obstructive pulmonary emphysema. The human chromosomal alpha 1-antitrypsin gene has been cloned and shown to contain three introns in the peptide-coding region. When the cloned alpha 1-antitrypsin gene was used as a hybridization probe to analyze Eco RI-digested genomic DNA from different individuals, two distinct bands of 9.6 kilobases (kb) and 8.5 kb in length were observed in every case. Further analysis using only labeled intronic DNA as the hybridization probe has indicated that the authentic alpha 1-antitrypsin gene resides within the 9.6-kb fragment. Thus the 8.5-kb fragment must contain another gene that is closely related in sequence to the alpha 1-antitrypsin gene. Using a series of human-Chinese hamster somatic cell hybrids containing unique combinations of human chromosomes, the alpha 1-antitrypsin gene as well as the sequence-related gene have been assigned to human chromosome 14 by Southern hybridization and synteny analysis.

Human immune interferon gene is located on chromosome 12

A cDNA clone for human immune interferon (IFN-gamma) gene sequences, plasmid p69, was used to chromosomally map the IFN-gamma gene by detecting human IFN-gamma gene sequences in DNA isolated from human-rodent somatic cell hybrids. We were able to map the IFN-gamma gene by correlating the human chromosomes present in these hybrids with the human specific 8.8 and 2.0 kilobase pair fragments produced by EcoRI digestion of genomic DNA. Southern blot analysis of 37 hybrid cell lines indicated that the gene for IFN-gamma was on human chromosome 12. A hybrid containing a portion of chromosome 12 localized the IFN-gamma gene to the p1205 leads to qter region.

Isolation of a human repetitive sequence and its application to regional chromosome mapping

Recombinant lambda phage Charon 4A with repetitive human DNA inserts have been constructed by using cellular DNA from a human-Chinese hamster ovary cell hybrid retaining the complete hamster genome and a single human chromosome 12. One recombinant phage, 12-11, contains several repetitive sequences, each with a different repetition pattern in the human genome. A 2.2-kilobase (kb) EcoRI fragment of this phage was subcloned in pBR325. This sequence has fewer than 5,000 copies in the human genome and does not cross-hybridize with Chinese hamster DNA. When the labeled 2.2-kb probe was hybridized to human chromosome 12 DNA digested with EcoRI, there was an intense band at the 2.2-kb position and a series of other discrete bands. The band pattern at positions other than 2.2 kb appears to be distinct for each human chromosome. The 2.2-kb fragment is composed of at least three subregions. The ends of the fragment are repeated more frequently in the genome than is the middle portion. Hybridization of chromosome 12 DNA with probes made to these subregions yielded simpler band patterns. By using a series of cell hybrids containing various deletions of human chromosome 12, five sequences related to the 2.2-kb fragment have been assigned regionally to a specific portion of the short arm of chromosome 12. These results demonstrate that certain repetitive sequences in the human genome can be used as genetic markers and may permit detailed regional mapping of human chromosomes.

Isolation and chromosomal localization of unique DNA sequences from a human genomic library

Recombinant bacteriophage lambda from a human genomic library were screened to indentify human DNA inserts having only unique sequences. Unique human inserts were found in about 1% of the phage screened. One recombinant phage, P3-2, was studied in detail. It contains a human insert of 14.7 kilobases with four internal EcoRI cleavage sites. A restriction map was constructed for EcoRI and BamHI sites. Hybridization of the 32P-labeled P3-2 probe to a Southern blot of EcoRI-digested total human DNA yielded distinct bands at positions corresponding to the human insert fragments contained in P3-2. By using a series of human-Chinese hamster somatic cell hybrids containing unique combinations of human chromosomes, the human DNA segment in phage P3-2 was assigned to human chromosome 22 by blot hybridization and synteny analysis. In addition, another human DNA segment, 11.4 kilobases, in phage P3-10 was assigned to human chromosome 10 by similar procedures. With this approach, more unique DNA sequences can be isolated, assigned to specific human chromosomes, and used as genetic markers for gene mapping and linkage, polymorphism, and other genetic studies in the human genome.

Regional mapping of the gene coding for enolase-2 on human chromosome 12

Enolase-2 (ENO2), previously termed 14-3-2 protein, is an isozyme of enolase that is enriched in neuronal tissue. The gene coding for ENO2 was previously assigned to human chromosome 12. The present study presents data for a regional mapping of gene ENO2 using cell hybrids containing various deletions of human chromosome 12. These deletions were produced by treatment with chromosome-breaking agents. Cytogenetic analysis has allowed assignment of ENO2 to the short arm of chromosome 12, in the region of pter-p1205. This assignment is consistent with the segregation pattern of the 93 hybrid clones analysed. The segregation pattern has also established the linear order of 6 genes on chromosome 12:pter-TPI-GAPD-LDHB-ENO2-centromere-SHMT-PEPB-qter. Estimation of the relative distances between the 6 genes on chromosome 12 has been made by a statistical mapping analysis of the segregation data of the hybrid clones. A set of deletion hybrids containing various combinations of these 6 markers has been established for a rapid regional mapping of genes in one of these regions on chromosome 12.

Assignment of the structural gene coding for albumin to human chromosome 4

Albumin is a developmentally regulated serum protein synthesized in the liver mainly during adulthood. Family studies using variant forms of albumin established autosomal linkage between albumin and group-specific component protein (GS). Since GC has been assigned to human chromosome 4, albumin can be indirectly assigned to the same chromosome; however no direct assignment has been made. Recently, the human albumin cDNA probe has been isolated and characterized. It thus permits a direct chromosomal assignment of the albumin gene in the human genome. When the cDNA probe was hybridized to the HindIII digested total human DNA, an intense band at 6.8 kb was present. When the probe was hybridized to the HindIII digested Chinese hamster CHO-K1 DNA, a less intense band at 3.5 kb was found, plus three other faint bands. When the probe was hybridized to a series of human/CHO-K1 cell hybrids retaining a complete hamster genome and various combinations of human chromosomes, it was evident that hybrids containing human albumin gene sequences could be readily distinguished from hybrids containing no human albumin gene. Analysis of 22 primary cell hybrids for the presence or absence of human albumin sequences has assigned the albumin gene to human chromosome 4. Similar results were obtained using another restriction endonuclease EcoR1. Thus, by direct assay of the genomic albumin gene sequences in the cell hybrids, we provide evidence for a direct assignment of the structural gene for human albumin to chromosome 4.

Regional assignment of human genes TPI1, GAPDH, LDHB, SHMT, and PEPB on chromosome 12

Karyological analysis was performed on a series of human-Chinese hamster cell hybrids containing deletions of human chromosome 12. Chromosome breakage was produced by treatment of the cells with either X-rays or 5-bromodeoxyuridine and near-visible light. The hybrid clones were analyzed for the presence or absence of the following five human gene markers known to be located on chromosome 12: triosephosphate isomerase-1 (TPI1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), lactate dehydrogenase-B (LDHB), serine hydroxymethyltransferase (SHMT), and peptidase-B (PEPB). Based on the correlation between the isozyme markers and karyological analysis of these clones, a regional map of the five human genes on chromosome 12 was established. The linear order for these genes is: pter-TPI1-GAPDH-LDHB-centromere-SHMT-PEPB-qter. The locations of these genes are: TPI1, GAPDH, LDHB: pter leads to p12; SHMT: q12 leads to q14; PEPB: q14 leads to qter. Statistical analysis similar to that of Goss and Harris (1975, 1977a, b) has been performed on the segregation data in the hybrid clones. The statistical map, in general, agrees with the cytogenetic map and further localizes PEPB to 12q21.

Induced segregation of human syntenic genes by 5-bromodeozyuridine + near-visible light

Chromosome-breaking agents have been used in two different procedures for promoting segregation of syntenic genes on human chromosome 12. In method A, a human-Chinese hamster cell hybrid containing the single human chromosome 12 was treated either with 5-bromodeoxyuridine BrdU + near-visible light or with X-rays. In method B, normal human fibroblasts were treated with BrdU + near-visible light followed by their fusion with a Chinese hamster glycine-requiring cell mutant CHO-K1/gly-A. Since the human complementing gene for serine hydroxymethyltransferase, an enzyme deficient in gly-A, lies on human chromosome 12, only those hybrids retaining that chromosome can survive the glycine-free medium. Clones isolated from both procedures were analyzed for the loss or retention of four other syntenic genes on chromosome 12, TPI, GAPD, LDH B, and PepB. The results demonstrate that method B is much more effective in generating clones with extensive marker losses. In addition, the segregation pattern and frequency obtained in this study provided information on the linear order of TPI and GAPD on chromosome 12.