Des-Leu angiotensin I: biosynthesis and drinking response

The crude rat and bovine synaptosomal lysate from brain can hydrolyze angiotensin I (AI) to des-Leu angiotensin I (AI-dL) and no further. This cytosolic enzyme has a specificity for angiotensin-related sequences, R-His-Pro-Phe-His-Leu and therefore named angiotensin-related carboxypeptidase (ARC). These studies led to the biosynthesis and purification of AI-dL in order to determine if it can provoke a drinking response. This nonapeptide is a potent dipsogen when injected into the cerebroventricles of rats. The drinking response probably requires a second hydrolysis to angiotensin II (AII) since both captopril and saralasin can inhibit this response.

Complexes of thrombin with secreted platelet proteins

A labeled 77-kDa complex formed when 125I-thrombin was added to platelet suspensions or to the supernatant solution of ionophore-activated platelets. Prostacyclin inhibited complex formation with whole platelets but not with the supernatant solution of ionophore-activated platelets. This is evidence that the complex formed with a factor secreted from activated platelets. Smaller complexes of 70 and 58 kDa formed between labeled thrombin and lysed platelets. The 77-kDa complex was necessary for the formation of a thrombin-thrombospondin complex.

Subcellular localization in rat brain of angiotensin-related carboxypeptidase activity distinct from converting enzyme

Whole brain synaptosomes contain both an isorenin activity and angiotensin-related carboxypeptidase activity. Further hydrolysis of des-Leu angiotensin I (AI-dL) occurs more slowly; hydrolysis of angiotensin II (AII) is negligible. Vasopressin and oxytocin but not vasotocin can inhibit angiotensin-related carboxypeptidase activity. Since AII has been shown to induce vasopressin secretion, this correlation suggests a feedback inhibition by vasopressin of this enzymatic cascade. Commercially available radioimmunoassays for AI and AII show a 3.4 and 6.0% crossreactivity, respectively. When the absolute concentration of AI-dL exceeded 500 ng/ml, both antibodies to AI and AII showed maximal displacement of radiolabel. This suggests that these antibodies may not distinguish between AI-dL from other peptides during immunocytochemistry.

Action-potential discharge in hippocampal CA1 pyramidal neurons: current source-density analysis

1. The site of origin of evoked action-potential discharge in hippocampal CA1 pyramidal neurons was investigated using the in vitro rat hippocampal slice preparation. 2. Action-potential discharge in pyramidal cells was evoked by stimulation of efferent pyramidal cell fibers in the alveus (antidromic) or afferent synaptic inputs in stratum oriens (SO) or stratum radiatum (SR). Laminar profiles of evoked extracellular field potentials were recorded at 25-micron intervals along the entire dendrosomatic axis of the pyramidal cell and a one-dimensional current source-density analysis was applied. 3. Suprathreshold stimulation of the alveus evoked an antidromic population spike response and current sink with the shortest peak latency in stratum pyramidale or proximal stratum oriens. A biphasic positive/negative potential associated with a current source/sink was recorded in dendritic regions, with both components increasing in peak latency with distance from the border of stratum pyramidale. 4. Suprathreshold stimulation of SO or SR evoked a population spike response superimposed upon the underlying synaptic depolarization at all levels of the dendrosomatic axis. The shortest latency population spike and current sink were recorded in stratum pyramidale or proximal stratum oriens. In dendritic regions, a biphasic positive/negative potential and current source/sink conducted with increasing latency from the border of stratum pyramidale. 5. A direct comparison of alvear- and SR-evoked responses revealed a basic similarity in population spike potentials and associated sink/source relationships at both the somatic and dendritic level and a similar shift in peak latency of spike components along the pyramidal cell axis. 6. It is concluded that the initial site for generation of a spike along the dendrosomatic axis of the pyramidal cell following antidromic or orthodromic stimulation is in the region of the cell body layer (soma or axon hillock). Action-potential discharge in dendritic regions then occurs as the result of a subsequent retrograde spike invasion of basal and apical dendritic arborizations.

Long-term increases in dentate granule cell responsivity accompany operant conditioning

The efficacy of synaptic transmission from the perforant path (PP) to the granule cells in the dentate gyrus (DG) of freely moving rats was monitored electrophysiologically over the course of training in an appetitively motivated, discriminated operant paradigm. Every day, 22 hr after behavioral sessions, evoked potentials were recorded from the DG following stimulation of the PP over range of current intensities and the amplitudes of the population spikes were measured. Behavioral conditions involved training in an operant conditioning paradigm or a session of free-feeding. Significant increases in population spike amplitudes were observed over the 8 d of training, but not over the 8 d of free-feeding. This training-induced increase in granule cell responsivity persisted for at least 10 d following the cessation of behavioral trials and was in many ways comparable to long-term potentiation (LTP), subsequently observed in these same rats 24 hr after tetanic stimulation. These data confirm and extend previous reports of synaptic enhancements following conditioning and suggest that such increases in synaptic efficacy may encode some aspect of learning.

Interleukin-2 production by lymphocytes from blood of children with arthritis is less suppressed than in systemic lupus or cystic fibrosis

Interleukin-2 (IL-2) production by cells from children with various forms of arthritis, systemic lupus erythematosus, and cystic fibrosis was compared. In all cases more IL-2 was detectable at 24 than at 48 h and production was increased by addition of indomethacin. Cultures from children with either active lupus or the pneumonia of cystic fibrosis produced very little IL-2, but cultures from children with arthritis produced apparently normal amounts. We conclude that depressed production of IL-2 in juvenile arthritis may be a secondary epiphenomenon and not a primary immunologic deficit.

Psychosocial risk and resistance factors among children with chronic illness, healthy siblings, and healthy controls

Psychosocial risk and resistance factors within the domains of parental functioning, family stressors, and family resources were examined as predictors of psychological adjustment and physical problems in juvenile rheumatic disease patients (N = 93), their healthy siblings (N = 72), and demographically matched healthy controls (N = 93). Family socioeconomic status and background variables showed few consistent relationships with child functioning. However, a constellation of risk and resistance factors tended to show comparable associations with functioning for patients, siblings, and controls. Higher parental depression and medical symptoms and more family stressors, sibling problems, and burden of illness on the family predicted more problems among the patients. These relationships held when disease duration and severity were controlled. For the siblings, increased parental and patient dysfunction, more family stressors, and less family cohesion and expressiveness were associated with more problems. Although the associations were not as strong, mothers' depression and lack of family cohesion and expressiveness also were related to more adjustment problems among the control children. These findings imply that there may be a general association between certain risk and resistance factors and childhood adaptation.

Spontaneous secretion of a proteoglycan releasing factor by mononuclear cells in juvenile arthritis

Patients with juvenile arthritis (JA) spontaneously produced a substance which accelerated proteoglycan loss from cultured articular cartilage. Peripheral blood mononuclear cells (PBMC) from 15 patients with JA were cultured for varying days, and cell-free PBMC conditioned media were added to articular cartilage cultures. Release of proteoglycan and collagen from cartilage was quantified by analysis of chondroitin sulfate and hydroxyproline content, respectively, after 4 days of culture. Conditioned media from PBMC of patients with systemic onset JA (3/3) and 5/7 patients with polyarticular JA increased release of proteoglycan when added to cartilage cultures. Mitogen stimulation of the PBMC was unnecessary for activity and addition of mitogen did not alter proteoglycan release. The PBMC conditioned media from the other patients (2/7) with polyarticular JA, from patients (3/3) with systemic onset JA which had progressed to polyarticular JA, and from patients with pauciarticular JA, did not enhance proteoglycan release without mitogen stimulation. PBMC of normal children produced media which enhanced proteoglycan release after mitogen stimulation. No conditioned medium accelerated proteoglycan release if cartilage was freeze killed before culture and none tested reduced cartilage collagen content.

Cell division age dependency of meiosis in an apomictic variant of Saccharomyces cerevisiae

The cell division age dependency of sporulation was investigated in a diploid strain of Saccharomyces cerevisiae (19el) which undergoes a single equational nuclear division during sporulation with consequent formation of asci containing two uninucleate diploid spores (apomictic dyads). Under modified nutritional conditions which partially restore meiosis and hence normal tetrad formation, newly formed (age 0) daughter cells were observed to be capable of formation of apomictic dyads but not of meiotic tetrads. Even under conditions in which only apomictic dyads developed, approximately 20% of the asci resulted from differentiation of newborn 'inexperienced' cells. Thus, the data indicated production of at least one bud to be a prerequisite for meiosis but not for apomixis; however, occurrence of at least one complete mitotic cell division cycle was evidently insufficient for the morphogenetic switch from diploid to haploid spore formation, since older cells bearing several bud scars often underwent apomictic dyad development, and some produced no spores.

Distribution of Calbindin-D28K 1 (CaBP) in the cerebral cortex and hippocampus of the epileptic (El) mouse

The distribution of Calbindin-D28K (CaBP), a calcium-binding protein that binds Ca2+ with high affinity, was measured by radioimmunoassay in various cortical regions of the epileptic strain of mice El. The El strain, in which seizures are induced by repeated vestibular stimulation, had significantly lower levels of CaBP in the hippocampus and dorsal occipital cortical areas than the control CF-1 strain. Following induction of seizures in the El strain, a further decrease in CaBP levels was observed in the hippocampal formation and ventral temporal cortical regions, areas where paroxysmal activity is generated in this strain. Considering the role of CaBP as an intraneuronal calcium buffer, the present findings indicate that neuronal calcium regulation is genetically altered in the El strain and is further disturbed during the events that lead to induction of seizures.

Psychosocial adaptation in juvenile rheumatic disease: A controlled evaluation

Juvenile rheumatic diseases are serious chronic illnesses potentially capable of disrupting a child's development and functioning. This study examined the psychosocial functioning of 43 children with severe rheumatic disease as compared to that of 52 children with a milder or inactive form of rheumatic disease. Both patient groups also were compared to 93 healthy children from demographically matched families. Data were obtained from parent reports, from physician evaluation, and, for children who were old enough, from self-reports. The severe patient group showed more parent-reported psychological and physical problems than both the mild patient group and the healthy controls. Compared to the mild group, the severe group also missed more days of school due to illness. Older children in the severe group were more likely to miss school due to illness and to participate in fewer social activities with their families and friends than the controls; however, the older children reported comparable mood and functioning in other areas. An expanded model is proposed to examine risk and resistance factors predictive of psychological and social dysfunction among children with severe chronic disease.

Different patterns of C3 and C4 activation in the varied types of juvenile arthritis

Quantitative assays for C3 and C4 activation were carried out simultaneously on blood from children with varied types of juvenile arthritis. Factor VIII-related antigen was also measured as an indicator of vascular damage. In active systemic juvenile arthritis, the C4d/C4 ratio was frequently elevated and was usually associated with elevated C3d/C3 ratios and elevated concentrations of factor VIII-related antigen. Children with chronic polyarticular arthritis, no matter which forms of onset they had had, also had increased levels of the C4d/C4 ratio, C3d/C3 ratio, and factor VIII-related antigen, but these were less consistent and were not associated with each other. In contrast, in pauciarticular arthritis there was a uniquely isolated increase in the C3d/C3 ratio. This work implies that there are different mechanisms responsible for complement activation in the different types and at different stages of juvenile arthritis.

Psychosocial functioning of siblings of children with rheumatic disease

The potential impact of an ill child on other siblings in the family was examined by comparing 72 siblings of children with rheumatic disease with 60 siblings of healthy children from demographically matched families. Psychosomatic, behavioral, emotional, and social problems, as reported by both the parents and the siblings, were investigated. Although siblings of patients with rheumatic disease generally were functioning as well as siblings of healthy children, they reported having more allergies and asthma. A set of vulnerability and protective factors was tested as predictors of sibling functioning. Cohesive and expressive family environments in which mothers and patients with rheumatic disease were functioning adequately promoted better adaptation among the siblings.

Angiotensin II generated by a human renal carboxypeptidase

Angiotensin II, the potent hypertensive octapeptide, can be generated by a sequential cleavage of the carboxyl-terminal leucine and histidine from angiotensin I by a human renal extract. This extract does not hydrolyze further the resulting octapeptide. The more widely recognized biosynthetic pathway is by the extracellular dipeptide cleavage of angiotensin I by an enzyme which also degrades bradykinin, i.e., angiotensin converting enzyme. The presence of a carboxypeptidase activity capable of generating but not further hydrolyzing angiotensin II was observed in an ammonium sulfate fraction of a human renal extract. This novel enzymatic activity is distinct from angiotensin converting enzyme activity in that it is not dependent upon calcium and is not inhibited by known angiotensin converting enzyme inhibitors.

Comparison of plasma glucose, serum insulin, and C-peptide responses to three isocaloric breakfasts in non-insulin-dependent diabetic subjects

While differences in glucose and insulin responses to specific carbohydrate foods have been reported, few data are available for mixed meals incorporating such foods. This study compared the plasma glucose (PG), serum insulin (SI), and C-peptide (CP) responses to three different isocaloric test breakfasts given in random order to eight insulin-treated non-insulin-dependent diabetes mellitus (NIDDM) patients. The test meals were selected from a hospital food exchange list and contained similar quantities of carbohydrate, protein, fat, and dietary fiber. The postprandial PG, SI, and CP responses to two of the test breakfasts (meal A: eggs, toasted wholemeal bread, orange juice, margarine, and milk; meal B: wheatflake biscuits, toasted wholemeal bread, milk, and margarine) were similar (meal A: 104.3 +/- 23.0 mg X h X dl-1, 5996 +/- 1108 microU X min X ml-1, and 89.8 +/- 25.4 pmol X min X ml-1, respectively; meal B: 104.9 +/- 21.6 mg X h X dl-1, 6268 +/- 1161 microU X min X ml-1, and 99.8 +/- 26.4 pmol X min X ml-1, respectively). Meal C, consisting of toasted muesli and skim milk, produced smaller glycemic and insulin responses (46.8 +/- 8.8 mg X h X dl-1; P less than .02, and 4369 +/- 700 microU X min X ml-1; P less than .05, respectively) than meals A and B and less endogenous insulin secretion (CP response 62.8 +/- 19.9 pmol X min X ml-1; P less than .05 compared with meal A, NS compared with meal B).(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibody profiles in juvenile arthritis

Serologic and correlational testing was performed in a series of 65 patients diagnosed as having juvenile arthritis (JA) and in 21 age matched controls to detect the presence of antinuclear antibodies (ANA), antibodies to ssDNA, IgM and IgG rheumatoid factor (RF), immune complexes (IC) and antibodies to bovine type I and human type II collagen. ANA were found in 51% of the JA patients; the highest incidence (75%) was noted in the pauciarticular onset disease group. Low levels of anti-ssDNA antibodies were detected in 22% of the patients, all of whom had active disease. IgM RF was detected in 35% of the JA patients but only 6% of patients had IgG RF. Similarly, about one fourth of the JA patients had IC detected by the Clq assay. Antibodies to bovine type I and human type II collagen were noted in about 12% of the JA patients.

Collateral specific long term potentiation of the output of field CA3 of the hippocampus of the rat

Long term potentiation (LTP) in response to brief high frequency trains has been reported for many pathways in the hippocampus. The mechanisms involved are still unclear. The present experiments set out to confirm reports in the literature that LTP of output from CA3 neurons can be specific to particular collaterals. Single pulses delivered to area CA3 produced field responses nearly simultaneously in area CA1 and in the lateral septum (LS). High frequency stimulation of CA3 produced long term potentiation of CA1 but not LS responses. The CA1 response to stimulation of the contralateral hippocampus did not potentiate when the CA1 response to CA3 stimulation showed long term potentiation. The CA1 and LS responses to CA3 stimulation showed similar strength-duration, strength-amplitude and frequency following characteristics. Their latencies were comparable to the latencies of antidromic activation of CA3 cells from CA1 and LS. Movement of stimulating electrodes to the region of the Schaffer collaterals increased the latency of the LS response and decreased the latency of the CA1 response but left the sum of these latencies unchanged. It was concluded that the CA3 and Schaffer stimulation were activating LS and CA1 collaterals of the same CA3 neurons. CA1 and LS responses to CA3 stimulation showed somewhat different paired pulse and frequency potentiation characteristics. These data confirm reports in the literature that long term potentiation is both input-specific and collateral-specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Unusual catheter tip placement from attempted central venous catheterization

Percutaneous catheterization of the subclavian and internal jugular veins is rapid and has overall complication rates from 0% to 11.2%. Noncentral placement of catheter tips has been reported in 1% to 16% of all cases. Two previously unreported locations for noncentral placement of catheter tips are described.

Complement activation products and factors influencing phagocyte migration in synovial fluids from children with chronic arthritis

Synovial fluids from children with chronic arthritis were examined simultaneously for the presence of complement activation products and factors affecting phagocyte migration. The concentrations of C3a and C5a, but not C4a, were found to be elevated relative to normal plasma. However, the C3a and C5a concentrations in synovial fluid did not correlate with C1q binding values or with degree of migration inhibition or chemoattraction caused by that fluid. Although this data implies complement activation occurs in inflamed joints in juvenile arthritis, the specific role of immune complexes remains unproven.

The neostriatal mosaic: compartmental distribution of calcium-binding protein and parvalbumin in the basal ganglia of the rat and monkey

Calcium-binding protein (CaBP) and parvalbumin are two proteins that are expressed in brain and bind calcium in the micromolar range. The immunohistochemical distribution of these two proteins was examined in the basal ganglia of rats and rhesus monkeys. In the striatum, CaBP immunoreactivity is localized to a subset of striatonigral projection neurons; CaBP-positive neurons are distributed in areas containing somatostatin-immunoreactive fibers and not in the complementary areas containing dense mu opiate-receptor binding. These biochemical labels mark, respectively, the matrix and patch compartments of the striatum. Previous studies have shown that striatal matrix neurons project to the substantia nigra pars reticulata, whereas striatal patch neurons project to the substantia nigra pars compacta. Consistent with the restricted localization of CaBP in the matrix projection neurons is the confinement of CaBP-immunoreactive afferent fibers to the pars reticulata. CaBP is also localized to a portion of dopaminergic and a few nondopaminergic neurons in the substantia nigra pars compacta and in most dopaminergic neurons in the ventral tegmental area. Parvalbumin immunoreactivity is localized to a subset of substantia nigra pars reticulata neurons and their axons. In the lateral striatum, some medium-sized aspiny interneurons are also parvalbumin immunoreactive. The distinct distributions of CaBP and parvalbumin in the basal ganglia are discussed in terms of their possible roles as intracellular calcium buffer systems related to the physiologic response properties of the neurons in which they are contained.

Reduction of rat hippocampal calcium-binding protein following commissural, amygdala, septal, perforant path, and olfactory bulb kindling

The calcium-binding protein (CaBP) content of the hippocampal formation was determined by radioimmunoassay in control and kindled rats. Kindling of a number of different sites resulted in a reduction in the CaBP content of the hippocampal formation, which was shown immunohistochemically to be restricted to the dentate granule cells and their processes. The maximum decline in CaBP varied with the different kindling sites: perforant path, 33%; commissural path, 32%; septum, 30%; amygdala, 18%; and olfactory bulbs, 15%. There were no changes in the CaBP content of the stimulated areas themselves. In cases where the kindling stimulus was delivered unilaterally (perforant path and amygdala), the maximum decrease in hippocampal CaBP was observed ipsilateral to the site of stimulation when the criterion for full kindling was established (six consecutive stage 5 motor seizures). Further kindling trials were required to produce a similar magnitude decrease in the CaBP content of the contralateral hippocampus. These observations are discussed both in relation to the possible role of CaBP in the establishment of a seizure response to kindling and also as a potential compensatory mechanism that may serve to overcome the epileptogenic effects of kindling.