Estimation of glomerular filtration rate in conscious dogs following a bolus of creatinine. Comparison with simultaneously determined inulin clearance

The renal clearance of creatinine was measured following orogastric administration in conscious dogs. Values of creatinine clearance were compared with simultaneously determined values of inulin clearance, when urine volume, glomerular filtration rate and volume status were acutely altered by a variety of experimental manoeuvres. At urine volumes greater than 20 microliters X min-1 X kg-1, creatinine clearance was not significantly different from inulin clearance. At low urine volumes there was some evidence of creatinine reabsorption. It is concluded that the bolus creatinine technique provides reliable estimates of glomerular filtration rate and is particularly applicable to long-term studies in conscious dogs.

Amino nitrogen metabolism following administration of individual amino acids or meat in conscious dogs

Normal conscious dogs were given a meal of meat or doses of individual amino acids by stomach tube. The concentration of amino nitrogen in systemic arterial plasma and the rate of urea production both increased; the magnitude and time course of these increases varied with the individual amino acid administered. There was a relationship between the plasma amino nitrogen concentration and urea production following L-serine, L-alanine, L-proline. dicarboxylic acids and L-cystine similar to that obtained after meat ingestion. It is suggested that these amino acids were transaminated as rapidly as they were absorbed to produce an increase in a general pool of amino acids. Following L-threonine, L-valine, D-serine and immediately after glycine, a small increase in urea production was accompanied by a larger increase in plasma amino nitrogen concentration. It is suggested that these amino acids 'escaped' transamination in the gut wall and liver and that the increase in plasma amino nitrogen was due to a high concentration of the individual amino acid administered.

Glomerular filtration rate following administration of individual amino acids in conscious dogs

Normal conscious dogs were given 100 mmol glycine, L-serine, L-alanine, L-threonine, L-proline, L-glutamic acid (50 mmol), L-aspartic acid and L-valine by stomach tube. All these amino acids increased glomerular filtration rate (G.F.R.). There was no increase in G.F.R. following L-cystine or D-serine. The intravenous infusion of L-proline, but not glycine, caused increase in G.F.R. The results suggest that the increase in G.F.R. was not due to a high plasma concentration of the individual amino acids but was related to the metabolism of amino acids with production of urea. It is postulated that after meat and during the metabolism of amino acids a factor is released which reaches and acts on the kidney to cause the increase in G.F.R.

Urinary crystal growth: effect of inhibitor mixtures

1. The crystal growth inhibitory activity of mixtures of known inhibitors and of mixtures of known inhibitors with normal urine was determined in calcium oxalate monohydrate and hydroxyapatite seeded crystal growth systems. 2. The inhibitory activity of the mixtures was compared with the measured activity of the individual components of the mixtures. All mixtures had inhibitory activity equal to the sum of the activities of their components, with the exception of RNA/urine mixtures in the calcium oxalate monohydrate system. 3. RNA/urine mixtures had inhibitory activity toward calcium oxalate monohydrate crystal growth which was less than would be predicted from the activity of the RNA and of the urine which were added. This reduced inhibitory activity was shown to be due probably to hydrolysis of RNA by the ribonuclease activity normally present in urine. 4. The results of these experiments make it possible to determine quantitatively the contribution of various naturally occurring urinary crystal growth inhibitors to the total measured inhibition observed in urine.

Prenatal and postnatal development of the cervical portion of the spine in the short-finned pilot whale Globicephala macrorhyncha

Fusion of the cervical spine in Globicephala macrorhyncha is a prenatal rather than a postnatal phenomenon which encompasses all cervical vertebra. This results in a relatively short, nonarticulated, composite cervical spine in this particular species. Cervicothoracic spine segments removed from fetuses demonstrated complete fusion of all cervical vertebra commencing during early prenatal development. C1 and C2 initially developed as a composite central cartilaginous unit, although laterally there was some separation through rudimentary interzone formation. However, C3 through C7 formed individual cartilaginous centra which were divided from each other by thin, well-demarcated concomitantly evident dividing the thoracic, lumbar, and caudal vertebra, although this was a very rudimentary intervertebral region). The first primary ossification center appeared in C2. Subsequently, primary ossification occurred in C7, and finally in C2 through C6, with ossification centers then progressively coalesced in the midline, from C2 to C7, in a craniocaudal sequence. This entire chondroosseous fusion process was completed during early gestation (probably less than 2 to 3 months of prenatal development), so that a composite "single" cervical vertebra developed that characterizes this species at birth and throughout postnatal development. Postnatally, ossification spreads laterally within each centrum, and also progressively removes the vestiges of the intervertebral material. The cranial end of C7 and the remainder of the cervical vertebra do not form secondary centers. An extensive fibrocartilaginous/hyaline cartilage bridge remains between C1 and C2, even after closure of the vertebral physes. Undoubtedly, this allows continued growth in C1 and C2, which become the dominant portion of the cervical unitary vertebra. Eventually, even this synchondrosis will disappear to form a completely osseous cervical mass.

Earthworms (Annelida : Oligochaeta) of Vanua Tu (New Hebrides Islands)

Twenty-one species of earthworms, one including two subspecies, are recorded from Vanua Tu (New Hebrides). They comprise 18 species of the 'Pheretima' group of genera, including Amynthas (five spp.), Metapheretima (eight spp.), Polypheretima (one sp.), Pheretima (two spp.) and Pithemera (two spp., one with two subspecies), and three common pantropical species, Dichogaster bolaui, Ocnerodrilus occidentalis and Pontoscolex corethrurus. Seven new species are described. The systematics of the earthworms of Vanua Tu are reviewed, and species in the 'Pheretima' group are classified according to the revisions of Sims and Easton (1972) and Easton (1979). A key is provided for identification of all species. Vanua Tu earthworms show little evidence of niche separation or local speciation and it is concluded that most, if not all, the species have been introduced to the archipelago by pre-European and European man. Relationships between Vanua Tu earthworms and those of other Pacific islands are discussed, and it is shown that a large proportion of the species belong to a widely distributed 'Pacific basin' group. The affinities of this group are with south-east Asian and Indo-Malayan forms, and they are considered to be a group analogous to the small group of European lumbricid species that have been spread by man through much of the temperate regions of the earth.

Uptake and binding of 1-methyl-1-nitrosourea (MNU) and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) by the isolated guinea pig pancreas

1-Methyl-1-nitrosourea (MNU) and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) are carcinogens which methylate nucleic acids and proteins and covalently modify proteins by carbamoylation (MNU) or guanidination (MNNG). Using MNU and MNNG labeled with carbon-14 in the individual carbon positions, the above reactions were quantitated in the isolated guinea pig pancreas, an organ susceptible to tumorigenesis by MNU. Freshly prepared pancreatic lobules were incubated with the labeled drugs (0.03, 0.3 and 1.0 mM) for one hour at 37 degrees C. Alkylated purines from hydrolyzed DNA were separated on Sephadex G10 and acid-soluble nuclear proteins were extracted and separated on polyacrylamide gels. Total uptake of all four labels into lobules was linear with concentration. Acid insoluble radioactivity also increased linearly except for MNNG methylation which plateaued between 0.3 and 1.0 mM. 7-Methylguanine formation by both compounds was approximately ten fold greater than 06-methylation. However, DNA modification by MNU exceeded that by MNNG, especially at the higher drug concentrations. No carbamoylation or guanidination of DNA was detected. Total binding (methylation plus carbamoylation/guanidination) to acid-extractable chromatin proteins was equivalent to DNA modification on a molar basis (approximately 0.35 and 0.08 pmol/microg for exposure to 1.0 mM MNU and MNNG, respectively). All histones were labeled by all drug preparations, with H2A being the principal site of methylation and H2B, H3 and H1 being the major targets of carbamoylation and guanidination. H4 was the least modified histone. Drug binding to cytoplasmic organelles also occurred. These results show a broad spectrum of nuclear and cytoplasmic modification of pancreatic cells by MNU and, to a smaller extent, MNNG.

Immune deficiency, thrombocytopenia and osteomyelitis in pediatric patients

Surgical decompression of osteomyelitis in pediatric patients should be an essential part of therapy in most cases. The initial deferral of prompt decompression in two patients because of underlying chronic, hemorrhagic (thrombocytopenic) disorders-one with Wiskott-Aldrich syndrome and one with Gaucher's disease-resulted in more serious and prolonged courses of the infectious processes. The complications might have been ameliorated by earlier drainage in each case. Based upon the experience gained from these two patients, we recommend early drainage, with appropriate treatment of the hemorrhagic disorder, to prevent more widespread dissemination or prolongation of osseous infection in similarly affected children.

The inhibition of calcium oxalate crystal growth by multidentate organic phosphonates

The effect of a number of structurally related multidentate organic phosphonates on the rate of crystal growth of calcium oxalate was studied as a function of pH. Rate constants were obtained at various concentrations for the phosphonates ethane-1-hydroxy-1,1-diphosphonate (EHDP), nitrilotri(methylenephosphonic acid) (NTMP), N,N,N',N'-ethylene-diaminetetra(methylenephosphonic acid) (ENTNP), and N,N,N',N'-hexamethylenediaminetetra(methylenephosphonic acid (HMTMP), at pH 5.00, 6.00, and 7.00. The effect of pH on the inhibitory activity of each of the phosphonates was considerable with effective concentrations of inhibitor decreasing two orders of magnitude, in some cases, as the pH was increased. At a given pH the potentially hexadentate ligands, ENTMP and HMTMP, were generally the most effective inhibitors. The results suggested that EHDP, at currently administered doses, provides only a moderate increase in the capacity of human urine to inhibit calcium oxalate crystal growth.

Indirect blood pressure measurements in the rabbit: correlations with direct aortic and ear pressures

Blood pressures in the central artery of the ear were determined in rabbits by the use of a modified Grant-Rothschild pressure capsule using two end-points defined as the complete cessation (occlusion) or restoration (opening) of the arterial blood flow. In normal rabbits, the opening values measured by the capsule were closely related to diastolic pressures measured directly in the aorta or in the central artery of the ear, whereas the values obtained during arterial occlusion were higher, by a reproducible amount, than the direct systolic recordings in both the ear and the aorta. In rabbits rendered chronically hypertensive, systolic and diastolic blood pressures measured directly in the aorta and the ear were less (in a predictable manner) than their correspondent occlusion and opening values recorded with the capsule. The amount of this difference increased proportionally as blood pressure increased. Differences between direct and capsular recordings were less consistent in rabbits made acutely hypertensive with infusions of angiotensin. Through regression analysis, systolic and diastolic pressures in the aorta and in the central artery of the ear can be reliably predicted from capsular reading.