A hypervariable repeated sequence on human chromosome 1p36.

When used to probe Southern blots of TaqI-digested DNAs from unrelated individuals, p1-79, a 900 bp subclone of a random human cosmid, revealed at least 50 fragments, many of which were polymorphic. Each of 27 unrelated individuals tested with p1-79 displayed a distinct band pattern. Similar variation was seen with several other enzymes, including HaeIII, MspI, PstI and PvuII, whereas other enzymes yielded primarily large fragments of greater than 40 kb. In situ hybridization of p1-79 showed that the loci of hybridization are clustered on human chromosome band 1p36; localization of all TaqI fragments to chromosome 1 was confirmed with a human-rodent somatic cell hybrid panel. DNA sequencing of p1-79 revealed several copies of a 39 bp repeat whose variation in copy number might be the basis of the observed length polymorphisms. Studies of 3-generation Utah families suggest that the numerous restriction fragments homologous to p1-79 are inherited as haplotypes, implying that recombination within this cluster of loci is rare and allowing the cluster to serve as a useful marker for human gene mapping.

Huntington disease-linked restriction fragment length polymorphism localized within band p16.1 of chromosome 4 by in situ hybridization.

A 5.5-kilobase (kb) single sequence DNA fragment (G8) reveals the DNA polymorphic locus D4S10 on Southern blot analysis. This locus is closely linked to Huntington disease and has been mapped to chromosome 4 short arm using human-mouse somatic cell hybrids, and specifically to chromosome 4 band p16 using DNA from individuals with deletions of chromosome 4 short arm who exhibit Wolf-Hirschhorn syndrome. With in situ hybridization techniques, we have confirmed the location of D4S10 on chromosome 4 and further localized it within band p16 utilizing five patients, four with overlapping chromosome 4 short-arm aberrations. The DNA segment G8 was hybridized to the mataphase chromosomes of the five patients. Two of them have different interstitial deletions of one of the chromosome 4 short arms (TA and BA), two have different chromosome 4 short-arm terminal deletions (RG and DQ), and one has a normal male karyotype. By noting the presence or absence of hybridization to the partially deleted chromosomes with known precise breakpoints, we were able to more accurately localize probe G8 to the distal half of band p16.1 of chromosome 4.

Oral cholestyramine and paregoric therapy for intractable diarrhea following surgical correction of catastrophic disease of the GI tract in neonates.

Ten surgical neonates with postoperative intractable diarrhea and secondary weight loss were treated with combination cholestyramine and paregoric therapy. Within 3-5 days all infants except two showed significant clinical improvement with a decreasing number of stools, an increase in the consistency of the stool, and gradual weight gain. The exact mechanism of action of cholestyramine is not clear. It may act by binding with bile salts and/or endotoxins in the bowel lumen or decreasing the motility of the bowel. Used in combination with paregoric, a known bowel motility depressant, the doses of each medication can be kept quite low thus avoiding undesirable side effects. Medium chain triglyceride formula is helpful in some of these infants to improve fat absorption further. Medication in all of these infants has been discontinued without any adverse effects.

Oxidation of ferrocytochrome c by mitochondrial cytochrome c oxidase.

Attempts to rationalize the kinetics of cytochrome c oxidation catalyzed by solubilized mitochondrial cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) have been based on assumptions of productive complex formation (Michaelis-Menten approach). However, the range of substrate concentrations used has not, in general, been sufficient to establish a general rate equation. Data adequate to derive such a rate expression are presented, as well as a method for estimation of constants which appear in the rate law deduced and reported herein. It is shown that either of two types of mechanisms, one assuming productive complex formation, as opposed to the other postulating dead-end complex formation, accurately predict the rate equation as deduced from experiment.