The intraoral use of EMLA cream in children: a clinical investigation

The use of 5 percent EMLA (an eutectic mixture of local anesthetics comprised of a mixture of prilocaine and lidocaine) as an intraoral topical anesthetic in children has been assessed in a clinical investigation. In a split-mouth study in twenty children there was no difference in the efficacy of EMLA and 5 percent lidocaine ointment in alleviating the pain of maxillary buccal infiltration injections of local anesthetics. EMLA did not differ significantly from placebo in the changes in pulpal responses of maxillary primary teeth to electrical stimulation before and after application in a double-blind split-mouth study in twenty children.

Synergistic effects of interleukin-11 with other growth factors on the expansion of murine hematopoietic progenitors and maintenance of stem cells in liquid culture

The effect of interleukin-11 (IL-11), alone and in combination with other hematopoietic growth factors, was studied in liquid suspension cultures of murine bone marrow. Stem and progenitor cell contents of input bone marrow 2 days after 5-fluorouracil (5-FU) treatment (FU2dBM) and lineage-depleted, Sca-1-positive FU2dBM (Lin-Sca+Fu2dBM) were compared with output values obtained after 6 days in different growth factor combinations. Stem and progenitor cell recoveries were measured by long-term in vivo competitive repopulation, spleen colony-forming unit (CFU-S), and in vitro limiting dilution long-term bone marrow culture (cobblestone area-forming cell [CAFC]) assays. IL-11, IL-3, IL-6, and Steel factor (SF) were tested separately and in combinations of two, three, and four factors. IL-11 was incapable of maintaining the survival of stem or progenitor cells as a single agent but synergized with either IL-3 or SF to expand progenitor cell output in cultures of FU2dBM. IL-11 greatly enhanced progenitor cell expansion from FU2dBM when added to two- and three-factor combinations of SF, IL-3, and IL-6. The recovery of long-term repopulating ability was enhanced four-fold by incubation in SF plus IL-11 compared to SF alone. IL-11 in combination with SF, IL-3, and IL-6 stimulated a 24,000-fold expansion of progenitor cells from stem cell-enriched Lin-Sca+FU2dBM. Overall, the results indicate that IL-11 is a potent synergistic factor for stem cell proliferation and expansion of progenitors in liquid culture.

Differences in nigral neuron number and sensitivity to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in C57/bl and CD-1 mice

The present study demonstrates that the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes significantly greater reductions in striatal dopamine levels in C57/bl mice than in CD-1 mice, thus confirming a greater sensitivity of the C57/bl mice to MPTP. To determine the possible reasons for this difference in MPTP sensitivity between these two mouse strains, we have compared both the organization and the number of substantia nigra (SN) neurons, the primary target of MPTP, in C57/bl and in CD-1 mice using immunostaining for tyrosine hydroxylase (TH) and calbindin-D28k (calbindin). In saline-injected animals, there is a significantly lower number of SN TH-positive and calbindin-positive neurons in C57/bl than CD-1 mice; no significant differences in the numbers of these neurons are found in the ventral tegmental area between the two strains. In MPTP-injected animals, the reductions in SN TH-positive neurons are significantly greater in C57/bl than in CD-1 mice. In contrast, MPTP does not cause any significant changes in the numbers of SN calbindin-positive neurons in either strain. The present study shows that C57/bl mice which have fewer SN TH-positive neurons are more sensitive to MPTP-induced toxicity than CD-1 mice. This observation suggests a possible inverse relationship between SN TH-positive neuron number and MPTP sensitivity. If correct, this hypothesis may be of major importance for Parkinson's disease since it is suggested that individuals at risk of developing this neurodegenerative disorder may have lower numbers of SN TH-positive neurons to start with. The present study also shows that SN calbindin-positive neurons are spared following MPTP administration. However, the observed difference in SN calbindin-positive neuron numbers does not account for the differential sensitivity to MPTP between these two mouse strains.

Synergistic interaction between interleukin-12 and steel factor in support of proliferation of murine lymphohematopoietic progenitors in culture

We have investigated the effects of interleukin (IL)-12 (natural killer cell stimulatory factor/cytotoxic lymphocyte maturation factor) on the proliferation of murine myeloid and lymphohematopoietic progenitors in methylcellulose culture. In the presence of erythropoietin (Ep), IL-12 alone failed to support colony formation by mononuclear and enriched marrow cells of normal mice. Steel factor (SF) alone supported primarily formation of granulocyte/macrophage (GM) colony formation. However, the combination of the two cytokines yielded a significant number of multilineage colonies. When tested on marrow cells from 5-fluorouracil (5-FU)-treated mice, the combination of IL-12 and SF, but not the single factors, was effective in support of formation of various types of colonies. Approximately 25% of these colonies yielded pre-B-cell colonies when replated in secondary culture containing SF and IL-7, indicating that IL-12 can interact with SF in supporting the development of primitive lymphohematopoietic progenitors. These results demonstrate that IL-12, a cytokine believed to be involved in the development of cell-mediated immune responses, has a wider range of activity, including committed myeloid and multipotent lymphohematopoietic progenitors.

Use of 5-fluorouracil to analyze the effect of macrophage inflammatory protein-1 alpha on long-term reconstituting stem cells in vivo

A macrophage-derived inhibitor of early hematopoietic progenitors (colony-forming unit-spleen, CFU-A) called stem cell inhibitor was found to be identical to macrophage inflammatory protein-1 alpha (MIP-1 alpha). We investigated the effect of MIP-1 alpha on the earliest stem cells that sustain long-term hematopoiesis in vivo in a competitive bone marrow repopulation assay. Because long-term reconstituting (LTR) stem cells are normally quiescent, an in vivo model was first developed in which they are triggered to cycle. A first 5-fluorouracil (5-FU) injection was used to eliminate later progenitors, causing the LTR stem cells, which are normally resistant to 5-FU, to enter the cell cycle and become sensitive to a second 5-FU injection administered 5 days later. Human MIP-1 alpha administered from day 0 to 7 was unable to prevent the depletion of the LTR stem cells by the second 5-FU treatment, as observed on day 7 in this model, suggesting that the LTR stem cells were not prevented from being triggered into cycle despite the MIP-1 alpha treatment. However, the MIP-1 alpha protocol used here did substantially decrease the number of more mature hematopoietic progenitors (granulocyte-macrophage colony-forming cells [CFC], burst-forming unit-erythroid, CFCmulti, and preCFCmulti) recovered in the bone marrow shortly after a single 5-FU injection. In vitro, MIP-1 alpha had no inhibitory effect on the ability of these progenitors to form colonies. This study confirms the in vivo inhibitory effect of MIP-1 alpha on subpopulations of hematopoietic progenitors that are activated in myelodepressed animals. However, MIP-1 alpha had no effect on the long-term reconstituting stem cells in vivo under conditions in which it effectively reduced all later progenitors.

Mutations in Cu/Zn superoxide dismutase gene are associated with familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a degenerative disorder of motor neurons in the cortex, brainstem and spinal cord. Its cause is unknown and it is uniformly fatal, typically within five years. About 10% of cases are inherited as an autosomal dominant trait, with high penetrance after the sixth decade. In most instances, sporadic and autosomal dominant familial ALS (FALS) are clinically similar. We have previously shown that in some but not all FALS pedigrees the disease is linked to a genetic defect on chromosome 21q (refs 8, 9). Here we report tight genetic linkage between FALS and a gene that encodes a cytosolic, Cu/Zn-binding superoxide dismutase (SOD1), a homodimeric metalloenzyme that catalyzes the dismutation of the toxic superoxide anion O2.- to O2 and H2O2 (ref. 10). Given this linkage and the potential role of free radical toxicity in other neurodenegerative disorders, we investigated SOD1 as a candidate gene in FALS. We identified 11 different SOD1 missense mutations in 13 different FALS families.

Physical mapping of chromosome 21

Chromosome 21, the smallest human chromosome, has been the subject of intense study because it is the chromosome which, when present in an extra copy, leads to Down Syndrome. Moreover, there are genes important for several human genetic disorders on this chromosome, and a significant number of individuals with aneuploidies of regions of the chromosome have been identified. A high fidelity, high resolution physical map of chromosome 21 will be of immense value in generating an accurate genotype/phenotype map of the chromosome and in identifying and isolating genes on the chromosome which may be responsible for various human genetic disorders. Here we describe the current status of our attempts to create such a map. This includes attempts to integrate various physical mapping approaches. Progress towards construction of a minimal set of yeast artificial chromosomes (YACs) spanning the chromosome is described.

Purification and biochemical characterisation of human and murine stem cell inhibitors (SCI)

We have recently characterised an inhibitor of haemopoietic stem cell proliferation (SCI/MIP-1 alpha) and report here on its purification and initial biological and biochemical characterisation. The activity can be detected by direct addition to the CFU-A stem cell assay and this simple test for inhibitory activity has greatly facilitated the purification of the molecule. The purification involves a combination of Mono Q ion exchange chromatography, heparin-sepharose affinity chromatography and Blue Sepharose affinity chromatography. The purified stem cell inhibitor is an 8 kD peptide which is identical to the previously described peptide macrophage inflammatory protein 1 alpha. The peptide has a natural tendency to form large self-aggregates and appears, in physiological buffers, to have a native molecular weight of around 90 kD. SCI is a heat stable, protease sensitive protein which is half maximally active at between 10 and 25 pM in the CFU-A assay. The self-aggregates can be disrupted by dilute solutions of acetic acid and it appears that disruption increases the specific activity of SCI preparations. We also report the characterisation of the human homologue of the stem cell inhibitor (human SCI/MIP-1 alpha) which is 74% identical to murine MIP-1 alpha and which shares all the above features of the murine inhibitor.

Hyperglycemia suppresses c-fos mRNA expression following transient cerebral ischemia in gerbils

The c-fos proto-oncogene is activated by transient cerebral ischemia. This activation may signify a specific genetic response to ischemia affecting tolerance to ischemia and ultimate cell survival. Hyperglycemia, which enhances brain injury from transient ischemia, was studied for its effects on this gene system in gerbils by measuring c-fos mRNA 2 h after 20 min of bilateral carotid artery occlusion. Brain c-fos mRNA was increased by ischemia (11.7 +/- 5.0, p less than or equal to 0.05, fold increase) compared to nonischemic controls (1.0 +/- 1.3). Pretreatment with 1 g/kg of glucose partially reduced postischemic c-fos mRNA (6.3 +/- 1.6, p less than or equal to 0.05) while 4 g/kg of glucose completely suppressed postischemic c-fos expression (0.7 +/- 0.3, p less than or equal to 0.05). These data indicate that hyperglycemia suppresses normal postischemic gene expression and suggest the possibility that such suppression is a predictor or even a contributor to hyperglycemia-enhanced ischemic brain damage.

The cost of rural health services in Papua New Guinea

In 1988 a countrywide study was conducted on the costs of rural health services in Papua New Guinea. 16% of all health centres and subcentres were surveyed. Information was collected on physical facilities, recurrent costs, staff time allocation, service outputs and quality of services. Wide variation was found in the costs of rural health facilities overall, and significant differences were found between the costs and outputs of health centres and subcentres. Average levels of service output were found to be similar at church and government facilities but average levels of utilization by the population were higher at church facilities. Despite government policy on extension of preventive health care, a strong emphasis was found on curative care. Many facilities were found to have significant excess bed capacity. Recurrent financing for transportation and maintenance was found to be inadequate.

Relationships between requests for psychiatric consultations and psychiatric diagnoses in long-term-care facilities

OBJECTIVE

The authors' objective was to investigate reasons for referral of elderly nursing home residents for psychiatric consultation and the relationship of these reasons for referral to psychiatric diagnoses.

METHOD

They examined 197 nursing home residents consecutively referred to a consulting team in a university-affiliated mental health center. These patients represented all patients evaluated by the consulting team at six nursing homes over a 2-year period (Sept. 1, 1984, through Aug. 30, 1986).

RESULTS

Reasons for referral were diverse but fell into seven broad clusters: behavioral problems; mood-related problems; consultations requested by involuntary treatment services, patients, physicians, or other referring agencies; psychotic features; physical signs; impaired activities of daily living; and other. Behavioral problems were most commonly cited and tended to be associated with dementia diagnoses. Mood-related reasons for referral were most strongly associated with diagnoses of affective disorders, and diagnoses of schizophrenia and adjustment disorder were each associated with two or more reasons for referral. However, reasons for referral were distributed widely across diagnostic groups and were relatively weak predictors of diagnoses.

CONCLUSIONS

The results illustrate the variety of problems for which nursing home staff are willing to seek psychiatric consultation but emphasize the need for professional psychiatric evaluation to establish a diagnostic base on which treatment interventions can be built.

Isoenzymes of alkaline phosphatase in epileptic patients receiving carbamazepine monotherapy

The effects of carbamazepine monotherapy were investigated in 20 female and 21 male epileptic patients to determine whether treatment would induce an increase in serum alkaline phosphatase (ALP) activity, a known effect of many anticonvulsant drugs. Serum total ALP activity was increased in nine out of the 41 patients (22%), serum bone ALP activity was increased in 10 (24%), and serum non-bone ALP activity was increased in three (7%). There was no significant difference when the mean of the patients' serum total ALP was compared with that of the controls. Twenty per cent of the patients with increased serum bone ALP had normal serum total ALP, indicating that increased serum bone isoenzyme activity may precede an increase in the total enzyme activity. This should be considered when interpreting results of increased total ALP in epileptic patients.

Nitrous oxide

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Focal cerebral infarction in cats in the presence of hyperglycemia and increased insulin

Although it has been well established that hyperglycemia increases cerebral damage following transient cerebral ischemia, its effect on permanent focal ischemia is controversial. We hypothesized that other factors associated with hyperglycemia, such as plasma insulin, may alter the brain's response to hyperglycemia. The objective of this study was to determine if hyperglycemia changes infarction size following 8 hr of middle cerebral artery occlusion in the anesthetized cat and to examine if changes in plasma insulin levels alter hyperglycemia's effects. Infarct size in hyperglycemic cats with increased plasma insulin (38.3 +/- 8.4, mean +/- SE) or in hyperglycemic cats without increased plasma insulin (30.5 +/- 7.6%) was not significantly different from that of ischemic controls (33.8 +/- 2.8%). However, the variability in infarct size tended to be greater (P = 0.0647) among all hyperglycemic cats compared to control animals. The source of the variability is unknown, but this observation is dependent on the exact nature of the focal ischemic insult (i.e., degree of collateral blood supply) and that this effect may vary greatly from individual to individual within a population.

Relationship between plasma glucose, brain lactate, and intracellular pH during cerebral ischemia in gerbils

The dose-response relation between plasma glucose and brain lactate and the relation of these parameters to intracellular pH during severe cerebral ischemia have not been well characterized over a wide range of plasma glucose levels. Experiments to delineate these relations in the gerbil model of global ischemia were performed by using phosphorus-31 nuclear magnetic resonance spectroscopy to measure intracellular pH and a new method to measure brain lactate. Ischemia increased final brain lactate linearly 4 mumol/g for every 100 mg/dl increase in plasma glucose up to 650 mg/dl (p = 0.0001, r2 = 0.9); beyond 650 mg/dl, saturation of the glucose transport-glycolysis system occurred. Plasma glucose correlated better with ischemic intracellular pH than did brain lactate. However, when brain lactate levels are compared with intracellular pH during ischemia, the relation may be threshold rather than linear. A narrow transition zone, during which ischemic intracellular pH decreased precipitously with increasing brain lactate, was observed between 17 and 22 mumol/g; below 17 mumol/g, intracellular pH remained stable at 6.8-6.9, whereas above 22 mumol/g, intracellular pH decreased maximally to about 6.2. The marked decrease in intracellular pH that occurs when brain lactate surpasses 17 mumol/g suggests that this sudden drop in intracellular pH may account for the "lactate threshold" for increased cerebral ischemic damage.

Identification and characterization of an inhibitor of haemopoietic stem cell proliferation

The haemopoietic system has three main compartments: multi-potential stem cells, intermediate stage progenitor cells and mature cells. The availability of simple reproducible culture systems has made possible the characterization and purification of regulators of the progenitor cells, including colony-stimulating factors and interleukins. In contrast, our knowledge of the regulators involved in the control of stem cell proliferation is limited. The steady-state quiescent status of the haemopoietic stem cell compartment is thought to be controlled by locally acting regulatory elements present in the stromal microenvironment, but their purification has been hampered by the lack of suitable culture systems. We have recently developed a novel in vitro colony assay that detects a primitive cell (CFU-A) which has similar proliferative characteristics, in normal and regenerating bone marrow, to the CFU-S (haemopoietic stem cells, as defined by the spleen colony assay) and which responds to CFU-S-specific proliferation regulators. We have now used this assay to purify to homogeneity a macrophage-derived reversible inhibitor of haemopoietic stem cell proliferation (stem cell inhibitor, SCI). Antibody inhibition and sequence data indicate that SCI is identical to a previously described cytokine, macrophage inflammatory protein-1 alpha (MIP-1 alpha), and that SCI/MIP-1 alpha is functionally and antigenically identical to the CFU-S inhibitory activity obtained from primary cultures of normal bone marrow cells. The biological activities of SCI/MIP-1 alpha suggest that it is a primary negative regulator of stem cell proliferation and that it has important therapeutic applications in protecting haemopoietic stem cells from damage during cytotoxic therapies for cancer.

Albumin Redhill (-1 Arg, 320 Ala----Thr): a glycoprotein variant of human serum albumin whose precursor has an aberrant signal peptidase cleavage site

Albumin Redhill is an electrophoretically slow genetic variant of human serum albumin that does not bind 63Ni2+ and has a molecular mass 2.5 kDa higher than normal albumin. Its inability to bind Ni2+ was explained by the finding of an additional residue of Arg at position -1. This did not explain the molecular basis of the genetic variation (since proalbumin contains adjacent Arg residues at -1 and -2) or the increase in apparent molecular mass. Fractionation of tryptic digests on concanavalin A-Sepharose followed by peptide mapping of the bound and unbound fractions and sequence analysis of the glycopeptides identified a mutation of 320 Ala----Thr. This introduces an Asn-Tyr-Thr oligosaccharide attachment sequence centered on Asn-318 and explains the increase in molecular mass. This, however, did not satisfactorily explain the presence of the additional Arg residue at position -1. DNA sequencing of polymerase chain reaction-amplified genomic DNA encoding the prepro sequence of albumin indicated an additional mutation of -2 Arg----Cys. This introduces a prepro sequence, Met-Lys-Trp-Val-Thr-Phe-Ile-Ser-Leu-Leu-Phe-Leu-Phe-Ser-Ser-Ala-Tyr- Ser-Arg-Gly-Val-Phe-Cys-Arg (cf.-Tyr-Ser-Arg-Gly-Val-Phe-Arg-Arg- in normal human pre-proalbumin). We propose that the new Phe-Cys-Arg sequence in the propeptide is an aberrant signal peptidase cleavage site and that the signal peptidase cleaves the propeptide of albumin Redhill in the lumen of the endoplasmic reticulum before it reaches the Golgi vesicles, the site of the diarginyl-specific proalbumin convertase.

The mechanisms of nitrous oxide scavenging devices

A recent publication discussing the concern with nitrous oxide pollution in dental offices and the methods available to reduce this risk aroused interest in scavenging systems. This is the first in a series of three articles and will explain the mechanisms of the nitrous oxide systems available. The second describes the testing of these systems under ideal conditions and the third will assess their efficiency in various dental offices and the factors which were found to detract from that efficiency.

The efficiency of nitrous oxide scavenging devices in dental offices

Five scavenging systems were installed in 10 dental office and the levels of nitrous oxide were closely monitored for each. While the readings were higher than the previous non-clinical study, all appeared to be reasonably efficient. The various factors which caused increases in background levels were also recorded in the investigation.

A comparison of the effectiveness of nitrous oxide scavenging devices

Four nitrous oxide scavenging systems were tested for their efficiency under ideal standardized conditions. The volunteers received 35% nitrous oxide for 20 minutes and the levels of nitrous oxide recorded and averaged every five minutes. No density was carried out. All four systems achieved levels below 30 parts per million. With the recommended limit for nitrous oxide levels in dental operatory being 50 parts per million (ppm) rather than the several thousand ppm reached without scavenging, it is necessary to ensure that the scavenging devices available are capable of achieving this level. To do so under normal dental operating conditions provides many variables, such as the type of procedure carried out, movement by the patient, ventilation efficiency of the operatory, type of mouth pack utilized etc. This investigation was therefore designed to eliminate all operator and procedure variabilities. Each system was evaluated under ideal identical conditions and with no actual treatment being carried out.

The combined effect of nitrous oxide and oxygen and electrical stimulation during restorative dental treatment

A total of 124 adult patients were treated with nitrous oxide (N2O) and oxygen (O2), an electrical analgesic, or a combination of N2O/O2 and an electrical analgesic during restorative dental procedures. The use of electrical analgesic or N2O/O2 without local anesthetics resulted in a high failure rate and poor patient acceptance. However, combining N2O/O2 sedation with electrically induced analgesia resulted in a statistically significant improvement over either technique used alone, and provided an overall 81% success rate when used during restorative dentistry.