Plasma apolipoprotein pattern in fish-eye disease examined by high-resolution two-dimensional electrophoresis

We compared the plasma protein patterns of the two living patients suffering from fish-eye disease with those of appropriate controls, using high-resolution two-dimensional electrophoresis. Quantitative abnormalities were detected in plasma polypeptides corresponding to the isoforms of apolipoproteins A-I and A-II. The disease was characterized by normal concentrations of proapo A-I but dramatically subnormal concentrations of the other apo A-I isoforms and apo A-II. No significant difference was detected in the concentrations of other plasma proteins. These findings are discussed in relation to other apolipoprotein disorders.

Plasma apolipoprotein pattern in fish-eye disease examined by high-resolution two-dimensional electrophoresis

We compared the plasma protein patterns of the two living patients suffering from fish-eye disease with those of appropriate controls, using high-resolution two-dimensional electrophoresis. Quantitative abnormalities were detected in plasma polypeptides corresponding to the isoforms of apolipoproteins A-I and A-II. The disease was characterized by normal concentrations of proapo A-I but dramatically subnormal concentrations of the other apo A-I isoforms and apo A-II. No significant difference was detected in the concentrations of other plasma proteins. These findings are discussed in relation to other apolipoprotein disorders.

Crohn's disease in two married couples

Only two examples of married couples where both partners have developed Crohn's disease have been reported previously from the United Kingdom. We describe two further examples; one where the index patient had developed Crohn's disease before marriage, and the spouse subsequently developed Crohn's disease and a second example in which both spouses developed Crohn's disease after marriage.

Electrochemical detection of biogenic amines following acylation by N-hydroxysuccinimide esters

A general methodology for the selective derivatization of amines, to enable quantitation by high pressure liquid chromatography with electrochemical detection, is presented. N-Hydroxysuccinimide active esters present in large excess are suitably mild acylating agents to derivatize selectively trace quantities of amines for electrochemical detection. The 2 separate problems of extraction yield and detectability can be solved by this derivatization method. Due to its lipophilicity the resulting N-acylated amine, as demonstrated with serotonin, is extracted efficiently into organic solvents during sample preparation for chromatography. Moreover, the acyl group introduced can be designed to be electroactive, thus extending the procedure to amines not readily oxidized, e.g., histamine and phenylethylamine.

The diagnosis of flat foot in the child

The term flat foot is surrounded by confusion and there is little to help the clinician to identify cases which require treatment and to avoid treating many children unnecessarily. Research for 25 years has been aimed at elucidating this problem by identifying and evaluating a series of signs and tests. These tests allow the recognition of the abnormal foot as early as possible, when efficient treatment is likely to be most effective. The results indicate that evaluation of the flat foot should be based on a combination of signs, with most emphasis on the result of the great toe extension test.

Two-dimensional electrophoresis of proteins in human serum: improved resolution by use of narrow pH gradients and prolonged electrophoresis

The limited resolution of serum proteins achieved with a simplified technique of two-dimensional electrophoresis (Clin. Chim. Acta 103: 51-59, 1980) has been improved by using different ampholyte (Ampholine) mixtures in the first dimension, to obtain relatively shallow pH gradients, and prolonged electrophoresis time in the second dimension. The technique has been further simplified, without negative effect, by decreasing the concentration of non-ionic detergent (first dimension), omitting both sodium dodecyl sulfate equilibration and the use of a stacking gel (second dimension), and by using an improved silver-staining procedure. Reverse-polarity isoelectric focusing and non-equilibrium pH-gradient electrophoresis have been successfully used to resolve the basic polypeptides in serum after deleting sodium dodecyl sulfate from the sample preparation. These combined techniques reveal over 1100 polypeptides in human serum. After immunodeletion of albumin, additional serum polypeptides are seen. Immunodeletion of serum proteins from plasma reveals polypeptides that are relatively specific to plasma.

Two-dimensional electrophoresis of proteins in human serum: improved resolution by use of narrow pH gradients and prolonged electrophoresis

The limited resolution of serum proteins achieved with a simplified technique of two-dimensional electrophoresis (Clin. Chim. Acta 103: 51-59, 1980) has been improved by using different ampholyte (Ampholine) mixtures in the first dimension, to obtain relatively shallow pH gradients, and prolonged electrophoresis time in the second dimension. The technique has been further simplified, without negative effect, by decreasing the concentration of non-ionic detergent (first dimension), omitting both sodium dodecyl sulfate equilibration and the use of a stacking gel (second dimension), and by using an improved silver-staining procedure. Reverse-polarity isoelectric focusing and non-equilibrium pH-gradient electrophoresis have been successfully used to resolve the basic polypeptides in serum after deleting sodium dodecyl sulfate from the sample preparation. These combined techniques reveal over 1100 polypeptides in human serum. After immunodeletion of albumin, additional serum polypeptides are seen. Immunodeletion of serum proteins from plasma reveals polypeptides that are relatively specific to plasma.

Analysis of human sweat proteins by two-dimensional electrophoresis and ultrasensitive silver staining

The polypeptide components of human sweat have been detected with the methylamine-incorporating silver stain (T. Marshall, 1984, Anal. Biochem. 136, 340-346) following high resolution two-dimensional electrophoresis. This technique reveals over 400 polypeptide components in 65 microliters of unconcentrated human sweat.

Artifacts associated with 2-mercaptoethanol upon high resolution two-dimensional electrophoresis

The presence of 2-mercaptoethanol in the protein denaturing solution used to prepare samples for high resolution two-dimensional electrophoresis can result in artifacts when the two-dimensional patterns are detected by silver staining. These are (i) spots of discrete isoelectric point and electrophoretic mobility, (ii) horizontal bands of the same electrophoretic mobility as the spots (corresponding predominantly to molecular weights of 54,000 and 68,000), and (iii) vertical streaks of variable length and intensity. Although the nature and source of artifacts have not been positively identified the evidence suggests that they are probably not inherent in the 2-mercaptoethanol itself but rather released by the latter from some component common to both the first- and second-dimension constituents of the electrophoretic system.

Sodium dodecyl sulfate polyacrylamide gel electrophoresis of serum after protein denaturation in the presence or absence of 2-mercaptoethanol

Human serum proteins were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis after protein denaturation in the presence or absence of 2-mercaptoethanol. Both electrophoretic techniques give characteristic and reproducible banding patterns and achieve a high degree of resolution within the limits of a one-dimensional separation. The major protein bands have been identified, and the merits of the two techniques are compared. Protein denaturation in the absence of 2-mercaptoethanol gives more discrete bands for the purpose of protein identification by maintaining the disulfide-bridge-dependent polypeptide associations characteristic of many serum proteins. However, simultaneous use of both electrophoretic techniques enhances identification by exploiting the response of an individual protein to mercaptoethanol treatment. The clinical potential of this approach for detecting protein disorders is discussed.

Leukaemia and childhood cancer in twins

Data from the United Kingdom on childhood leukaemia and childhood cancer in twins and from the United States on leukaemia in twins are analysed by a new method. The method distinguishes determinants occurring before the stage of pregnancy corresponding with the cleavage of MZ pairs, from determinants occurring after this point. It derives estimates of the frequencies of each class of determinant. Different aetiological models are characterised by particular combinations of frequencies, and can thus be identified. The results of the analysis suggest that the major determinants of childhood leukaemia, and possibly of the solid cancers as well, operate before the time of cleavage. They operate either on the early zygote or its component germ cells. These early determinants are not, however, sufficient causes and require combination with postcleavage determinants, which subsequently occur in about a quarter of all children, before leukaemia can ensue.

Sodium dodecyl sulfate polyacrylamide gel electrophoresis of serum after protein denaturation in the presence or absence of 2-mercaptoethanol

Human serum proteins were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis after protein denaturation in the presence or absence of 2-mercaptoethanol. Both electrophoretic techniques give characteristic and reproducible banding patterns and achieve a high degree of resolution within the limits of a one-dimensional separation. The major protein bands have been identified, and the merits of the two techniques are compared. Protein denaturation in the absence of 2-mercaptoethanol gives more discrete bands for the purpose of protein identification by maintaining the disulfide-bridge-dependent polypeptide associations characteristic of many serum proteins. However, simultaneous use of both electrophoretic techniques enhances identification by exploiting the response of an individual protein to mercaptoethanol treatment. The clinical potential of this approach for detecting protein disorders is discussed.

Underwater life support based on immobilized oxygen carriers

One of the primary problems that hinders humans in their efforts to explore and develop the ocean realms is the lack of a ready supply of oxygen. Practical methods have not yet been devised for using the vast amount of oxygen dissolved in ocean waters for human life support in an undersea environment. Fish and other water-breathing animals have solved this problem by utilizing hemoglobin as a molecular oxygen pump. To achieve a similar oxygen extraction capability, we have explored various methods of oxygen extraction that are based on immobilized forms of hemoglobin. Improved methods for immobilizing hemoglobin or other oxygen carrying molecules and a method for extracting the available dissolved oxygen from natural waters and other fluids are described. The techniques that have been developed allow for immobilization of oxygen carriers at high concentration in a state where they are capable of reversible oxygen binding, and also allow for regeneration of the carrier in the event of oxidation of the oxygen-binding site.

Detection of protein in polyacrylamide gels using an improved silver stain

A much improved silver staining procedure for the detection of protein in polyacrylamide gels of 0.8-3.0 mm thickness is described. It achieves very high sensitivity (detecting less than 0.01 ng bovine serum albumin/mm2) by overstaining and subsequently removing nonspecific background stain using a modified, reliable destaining procedure. Maximum sensitivity follows prediamine equilibration in 0.1% (w/v) formaldehyde solution. With two-dimensional electrophoresis the improved staining procedure reveals greater than 200 polypeptides in unconcentrated human urine and greater than 150 polypeptides in a single human fingerprint.

Urgent cholecystectomy

A retrospective review of cholecystectomy at the Naval Regional Medical Center, Portsmouth, Virginia revealed 92 patients (22%) who had urgent or early operation for acute cholecystitis. There were no infections or deaths in this group and the complication rate was similar to that of patients who had elective cholecystectomy. We advocate liberal use of intraoperative cholangiography in these patients. Interestingly, a high number of positive common duct explorations were found in those patients with a bilirubin level of over 4.0 mg/dl.

Polyoma virus transformation and two-dimensional electrophoresis patterns of baby hamster kidney cell native proteins

The protein extracts of baby hamster kidney cells (BHK 21/C13) before and after malignant transformation by polyoma virus were resolved by isoelectric focusing in the first dimension and electrophoresis on concave 4-24% (w/v) polyacrylamide gradient gels in the second dimension. The resulting two-dimensional patterns were visualised by ultrasensitive silver staining. Major differences were observed in the protein distribution patterns of the two cell lines. Brief trypsinisation of the cells, prior to extraction of cell protein, had little effect upon the protein patterns of BHK cells. Similar treatment of the transformed cells markedly reduced the staining intensity of a string of spots which were present in far greater abundance than in the original BHK cells. The findings suggest that these proteins are located on the surface of the transformed cells and probably under the surface prior to transformation.

Behavioral and physiological effects of ethanol in high-risk and control children: a pilot study

Blood and breath acetaldehyde levels were measured following ethanol ingestion (0.5 ml/kg) in 11 boys familially at risk for alcoholism and 11 age-matched controls. No significant differences were found between groups for acetaldehyde, objective, or subjective measures of intoxication. Previous reports of acetaldehyde as a marker of risk for alcoholism were not confirmed. Baseline behavioral state predicted response to alcohol. Children tended to have a subjective response in a direction opposite from the baseline mood state.

Treatment of cryptorchidism with pulsatile luteinizing hormone-releasing hormone (LH-RH)

This preliminary report describes a new method of treating bilateral cryptorchidism that may modify the need for surgical intervention. Four of five boys (3 1/2, 3 1/2, 7, 11 and 12 1/2 years of age) given hourly subcutaneous pulses of luteinizing hormone-releasing hormone (LH-RH, 10 to 100 micrograms/day, given in a 3-min pulse every hour) showed evidence of testicular descent after 3 to 19 weeks. The battery-operated, programmable syringe driver was well tolerated by the boys, and the daily insertion of the scalp-vein needles was managed at home by their parents.

Relationships between mortality, visual acuity and microfilarial load in the area of the Onchocerciasis Control Programme

The relationships between onchocercal infection, visual acuity and mortality have been examined using epidemiological data gathered by the Onchocerciasis Control Programme from 66 villages in West Africa. All of these villages were surveyed at least twice. 18,778 persons were registered at the first surveys which were conducted around the time when control activities started. The second surveys were conducted two to five years later. 14,961 persons (79.7%) were alive and registered again, 786 (4.2%) had died, 2776 (14.8%) had moved and 255 (1.4%) could not be traced. The prevalence of blindness and of visual damage other than blindness both increased markedly with age, and the degree of visual damage was strongly associated with level of microfilarial infection. Among adults, the prevalence of blindness was higher for males than for females at all ages. The prevalence and intensity of microfilarial infection were also higher among males but this was not sufficient to explain their excess blindness. Logistic regression analysis showed that males were 1.5 times more likely to be blind than females of the same age and same level of microfilarial infection. The presence of visual damage at the first survey considerably increased the risk of mortality between the first and second surveys for both males and females. Mortality rates were three to four times higher among the blind and about 1.5 times higher among those with visual damage other than blindness compared with those with no visual damage. There was some evidence, for males but not for females, that mortality was also directly related to microfilarial load.(ABSTRACT TRUNCATED AT 250 WORDS)

Excreta disposal facilities and intestinal parasitism in urban Africa: preliminary studies in Botswana, Ghana and Zambia

The relationships between intestinal parasitism and excreta disposal technologies in Gaborone (Botswana), Ndola (Zambia) and Kumasi (Ghana) were investigated. Parasitic prevalence and intensity rates amongst groups of urban residents having similar socio-economic status and housing, but different excreta disposal technologies, were compared. In Gaborone, there was no evidence of a difference in intestinal parasitism between those using aqua privies and having access to public taps and those in identical houses enjoying flush toilets, in-house water connections and showers. In Ndola, the group with sewered aqua privies had larger houses, cleaner toilets, better water supplies, longer residence and more people in paid employment than the groups using pit latrines or communal flush toilets. Despite this, the sewered aqua privy users were not found to be different from the other groups with regard to hookworm and protozoal infection but had significantly higher Ascaris infection rates. In Kumasi, despite the differences in toilet type--from squalid communal aqua privies, through often fouled bucket latrines to well-maintained flush toilet systems--and despite also the differences in water provision, no evidence was obtained of any differences in intestinal parasitism between the groups studied. These findings suggest that the provision of superior water and sanitation facilities to a small cluster of houses, or to houses scattered through an area, may not protect those families from infection if the over-all level of faecal contamination of the environment is high. The sample sizes and response rates achieved in this study were low and follow-up studies, employing the same methodology but with larger samples, are recommended.

Variations in the prevalence and intensity of microfilarial infections by age, sex, place and time in the area of the Onchocerciasis Control Programme

Epidemiological data gathered by the Onchocerciasis Control Programme from 66 villages in West Africa have been analysed. All of these villages were surveyed twice and 10 a third time. The first surveys were conducted around the time when control activities started and provide baseline data against which to assess the effectiveness of control. The second and third surveys were conducted two to five years later. 18,778 persons were registered in the first surveys and 15,783 (84.1%) were examined for microfilariae. The prevalence of microfilarial infection was higher among males, increased rapidly with age in both sexes until about 25 years and levelled off at about 90% in males and 85% in females. The age-sex adjusted prevalence rates in different villages varied from 5% to 93% but were above 60% in three quarters of the villages. After two to five years of control there was an over-all fall in the prevalence of infection of about 4 to 5% a year. Among children born since control started, only seven of 1871 examined were found to be infected with microfilariae compared to an expected number of 79, had there been no change in prevalence rates.

Variations in responses to non-steroidal anti-inflammatory drugs

1 This paper assesses the variability in the response of patients with rheumatoid disease to a group of non-steroidal anti-inflammatory drugs (NSAID). 2 Thirty six patients were divided into three groups and each group received a set of four NSAID. The different drugs were each given three times daily for a week and the treatment order was randomised. 3 The study demonstrated marked variability and unpredictability in patient responses and cast doubt on the value of comparative trials of different NSAID.

Secular change in birthweight of Asian babies born in Birmingham

We have studied changes in the birthweight of Asian babies born alive at this hospital between 1968 and 1978. In 1978 Pakistani babies were 139 g heavier but Indian babies only 25 g heavier than 10 years earlier. Contributing to these changes were significantly fewer short mothers and primiparae among Pakistanis, and non-significant increases in gestational age and intrauterine growth (that is, weight centile after allowing for gestational age, parity, and maternal height). Among Indians there were significant increases in maternal height and gestational age, but parity was reduced and intrauterine growth did not increase. In both groups there were fewer teenage mothers, but whereas among Pakinstanis birth intervals of less than one year were less common, there was no such reduction among Indian mothers. The secular change suggests that genetic factors are unlikely to be the major reason why Pakistani babies born in Birmingham are lighter than European babies, and that environmental factors play an important role. Efforts to increase birthweight need to consider both the mothers' physical environment during pregnancy and prepregnancy factors influencing growth in childhood, age at first pregnancy, and birth interval. The study shows a need to describe an 'Asian' population with details of their sub-ethnic structure. The sub-ethnic and secular differences further suggest that a single 'Asian' standard for birthweight and intrauterine growth may be inappropriate; the use of international reference data with which all infants may be compared is preferable.

Clinical limitations of the estimation of glomerular filtration rate from height/plasma creatinine ratio: a comparison with simultaneous 51Cr edetic acid slope clearance

A retrospective comparison of single determinations of glomerular filtration rate measured by 51chromium-edetic acid slope clearance (CEDTA) and height/plasma creatinine ratio (Ht/PC) was undertaken in 199 children aged between 3 and 16 years. Analysis of the data indicated that only if Ht/PC less than or equal to 1.2 cm/mumol per 1 was the relationship between Ht/PC and CEDTA linear. Over this range where renal function is significantly impaired the confidence limits for individual prediction of glomerular filtration rate were so wide that a definitive measurement of renal function would be necessary in clinical practice. Where Ht/PC greater than or equal to 1.2 the relationship was non-linear and the predictive confidence limits very wide. To apply the technique as a screening test for normal renal function (CEDTA greater than or equal to 80 ml/min per 1.73 m2) the Ht/PC would need to exceed 2.16. In our study this would have detected 57 out of 131 patients who had normal glomerular filtration rates and erroneously included 2 out of 68 with subnormal renal function.

The selection and training of volunteers for a rural, home-based hospice program

Volunteers are essential to smaller hospice care programs. These volunteers must be selected and trained to provide these services. The training program has several goals: content acquisition, experimental learning, mutual screening and selection, team building, and public relations. Selection processes avoid persons who have rigid beliefs, unresolved grief, or negative personalities as well as those who talk too much. The training uses many teaching methods to emphasize hospice philosophy, team building, communication skills, death awareness, empathy skills, basic nursing skills, impact of death on family, cancer information, pain control, and physician-care factors. Concrete examples of how each of these themes is accomplished are included in the paper. This program has worked well in preparing a group of volunteers for a rural, home-based hospice program in northern Michigan and represents one example of an effective approach.

Beta-thromboglobulin in antecubital vein blood in relation to history of a stroke

The levels of beta-thromboglobulin (BTG) have been measured in the blood of 22 male and 22 female elderly patients who gave a past history of stroke, and in 31 males and 88 females of comparable age who gave no such history. Comparisons were made within and between the groups. In the stroke patients the relationship between BTG and age was not significant for either sex, nor was there a difference between the sexes. In the BTG/time from stroke relationship the females showed significantly higher levels the longer the time that had elapsed since the stroke, and this could not be explained solely by the factor of ageing. For males, on the other hand, there was a non-significant fall in BTG with days from stroke. In 'normal' subjects the BTG/age relationship was significant in females but not in males. No significant differences were demonstrated between the BTG/age relationships between the stroke and control groups and this was true for both sexes. The potential value of estimations of BTG in the elderly is discussed.

The influence of racial mix on comparisons of perinatal mortality rate between Area Health Authorities

The proportion of births to women of New Commonwealth origin in different Area Health Authorities (AHAs) varies widely. The influence of this varying proportion in contributing to differences in perinatal mortality rate (PNMR) between authorities is examined. Firstly, it is shown that the two main 'immigrant' groups have adverse PNMRs compared with Europeans, and that there is a positive correlation between the proportion of immigrant births in an Area and the PNMR. Secondly it is shown that immigrants have PNMRs (standardised for birth weight distribution) better than those of Europeans, and that there is a negative correlation between the proportion of immigrant births in an Area and the standardised PNMR of the whole Area. Thirdly, based on data from Birmingham a correction factor is developed and applied to the standardised PNMR to examine the effect of adjusting for racial mix. Factors other than birthweight contributint to variation between races in their PNMRs are discussed. It is concluded that the effect of race in contributing independently of birthweight to variation between Areas in respect of PNMRs is insufficient to invalidate inter-Area comparisons.

A simplified technique of high resolution two-dimensional electrophoresis: serum immunoglobulins

A relatively simple, inexpensive technique is described for high resolution two-dimensional electrophoresis of human serum proteins. The technique clearly resolves the heavy chains of IgG, IgA and IgM, the positions of which have now been established. The technique is highly reproducible for normal serum. Distinct changes were observed upon examination of the sera of patients with IgG OF IgA myelomatosis or Waldenström's macroglobulinaemia. The technique should prove valuable in both the study of immunoglobulin disorders and studies into the fine structure of highly purified immunoglobulins.

Disease concordance and sex similarity in twins

Disease patterns in twins may show the presence of genetic or of environmental causes. Two arguments of inference have been used. Discordances between monozygotic twins have been taken to indicate the presence of environmental determinants; and high levels of concordance in monozygotic (MZ) pairs compared with dizygotic (DZ) pairs have been taken to indicate the presence of genetic causes. Neither argument is rigorous and, at this level, neither is quantitative.

An investigator cannot always establish the zygosity of individual twin pairs, and many have therefore used indirect arguments, based upon Weinberg's differential method.¹ Thus, the number of MZ pairs in a randomly selected sample of twin pairs may be estimated by subtracting the number of unlike-sexed (U) from the number of like-sexed pairs (L). The proportion of MZ pairs is then (L - U)/(L + U), and of DZ pairs 2U/(L + U). Cannings² showed that in twins which are randomly selected, and when the proportion of males is 0·5, these formulae are maximum-likelihood estimators; also that their validity is unaffected by differential prenatal viability of MZ and DZ twins.

However, in the context of investigating aetiologies we need to ask whether these relationships remain true in twins which are not selected randomly, but because a particular disease occurred in one or both of the pair. This distinction has not always been clearly made in the past. It turns out to be crucial.

Smith,³ for example, was led to an erroneous conclusion with respect to the aetiology of Down's disease. This he later recognised,⁴ and showed that the formulation of a correct method for estimating the proportions of the MZ and DZ twins depended upon the prior choice of a model of pathogenesis. It was necessary to decide in advance whether the disease-determining events occurred before or after the point of MZ cleavage. Distortions of the Weinberg rule also occur in sex-linked recessive transmission where the U:L ratio among DZ pairs is other than 1:1; it is this ratio upon which the validity of the Weinberg method chiefly depends. For the investigator examining diseases the causes of which are not known, the necessity to make assumptions about the aetiology of the disease before he even begins his analysis introduces a disturbing circularity. These considerations provide the background to this paper.

beta-thromboglobulin in antecubital vein blood--the influence of age, sex and blood group

Samples of blood for estimation of beta-thromboglobulin (B.T.G.) in normal subjects have been obtained both from blood donors at the end of their donation and from other volunteers by standard venepuncture. The former was a satisfactory method in males only. By standard venepuncture females have on average lower values than males and in the pre-menopausal age groups the difference is statistically significant. Mean values vary little up to 59 years after which they rise slowly but steadily. There is no significant difference in the mean B.T.G. values between the ABO blood groups.

Genetic analysis of the mutation female-lethal in Drosophila melanogaster

A genetic analysis was made of theFemale-lethal(Fl) locus ofDrosophila melanogaster. This is anX-linked mutation which causes lethality only in females. Other alleles do not complementFland are either lethal or sterile when homozygous in females. Complementation studies onFlalleles demonstrate that there is no simple ranking of these alleles in terms of severity of phenotypic effect. Dosage manipulation ofFlalleles indicates that the sex-specificity is not a consequence of gene dosage effects. Viability studies on males carryingFlalleles show thatFlalleles have no effect on viability regardless of the presence or absence of aYchromosome. TheFllocus is therefore sex-specific. The hypothesis thatFl+ is involved in the establishment of imaginal phenotypic sex cannot be substantiated on the basis of experiments utilizing sex-change mutations.

The isolation and characterization of the high-molecular-weight glycoprotein from pig colonic mucus

1. A high-molecular-weight glycoprotein constitutes over 80% by weight of the total glycoprotein from water-soluble pig colonic mucus. 2. It was isolated from from nucleic acid and non-covalently bound protein by nuclease digestion followed by equilibrium centrifugation in a CsCl gradient. 3. The glycoprotein has the following composition by weight: fucose 10.4%; glucosamine 23.9%; galactosamine 8.3%; sialic acid 9.9%; galactose 20.8%; sulphate 3.0%; protein 13.3%; moisture about 10%. 4. The native glycoprotein has the high mol.wt. of 15 X 10(6). 5. Reduction of the native glycoprotein with 2-mercaptoethanol results in a glycoprotein of mol.wt. 6 X 10(6). 6. Pronase digestion removes 29% of the protein (3% of the glycoprotein) but none of the carbohydrate. 7. The molecular weight of the Pronase-digested glycoprotein is 1.5 X 10(6), which is halved to 0.76 X 10(6) on reduction with 2-mercaptoethanol. 8. The contribution of non-covalent interactions, disulphide bridges and the non-glycosylated peptide core to the quaternary structure of the glycoprotein are discussed and compared with the known structure of pig gastric glycoportein.