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Biomedical subjects

M Janes

Publications and source records attributed to M Janes.

12 recordsLinked to original sources
PubMed2004

Inactivation of pathogenic bacteria by cucumber volatiles (E,Z)-2,6-nonadienal and (E)-2-nonenal.

The effects of (E,Z)-2,6-nonadienal (NDE) and (E)-2-nonenal (NE) on Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium were investigated. A suspension of each organism of 6 to 9 log CFU/ml was incubated for 1 h at 37 degrees C in brain heart infusion solution that contained 0 to 500 or 1,000 ppm of NDE or NE. Depending on concentration, exposure to either NDE or NE caused a reduction in CFU of each organism. Treatment with 250 and 500 ppm NDE completely eliminated viable B. cereus and Salmonella Typhimurium cells, respectively. L. monocytogenes was the most resistant to NDE, showing only about a 2-log reduction from exposure to 500 ppm for 1 h. Conversely, this concentration of NDE caused a 5.8-log reduction in E. coli O157:H7 cells. NE was also effective in inactivating organisms listed above. A higher concentration of NE, 1,000 ppm, was required to kill E. coli O157:H7, L. monocytogenes, or Salmonella Typhimurium compared with NDE. In conclusion, both NDE and NE demonstrated an apparent bactericidal activity against these pathogens.

Aldehydes↗
PubMed2001

Viral levels in newborn African infants undergoing primary HIV-1 infection.

We examined weekly changes in viral levels in seven untreated infants infected with HIV at birth. Viral levels spiked immediately but reverted quickly to plateau levels typical of infant HIV infection within 2 weeks of first detected viraemia. We speculated that the depletion of naive, susceptible cells is responsible for the rapid decrease in spike levels and that the rapid replacement of lymphocytes in infants causes the high plateau viral levels (10(5) copies/ml) to be sustained.

HIV Infections↗
PubMed2000

A randomized trial comparing peripherally inserted central venous catheters and peripheral intravenous catheters in infants with very low birth weight.

BACKGROUND/PURPOSE: To determine whether percutaneously inserted central venous catheters (PICC) and peripheral intravenous catheters (PIV) in infants with very low birth weight (VLBW) differ with respect to (1) incidence of sepsis, (2) number of insertion attempts and catheters required for total intravenous therapy, (3) courses of antibiotics, and (4) total duration of intravenous (IV) use. METHODS: A randomized comparative trial was conducted involving 63 VLBW infants (<1,251 g) who required IV therapy. Infants were assigned randomly at 1 week of age to either a PIV or a PICC catheter and followed up prospectively until an IV was no longer required or the infant was transferred out of the neonatal intensive care unit. RESULTS: Data were analyzed on an intention-to-treat basis. There was no difference in the incidence of sepsis (P = .64), number of courses of antibiotics (P = .16), or total duration of IV use (P= .34) between the 2 groups. The number of insertion attempts required for total IV therapy was significantly lower in the PICC group than in the PIV group (P = .008). There also was a significantly lower number of total catheters utilized in the PICC group (P = .002). When data were controlled for birth weight strata the results were similar. CONCLUSION: PICC lines reduced the number of painful IV procedures in VLBW infants without additional morbidity.

Catheterization, Central Venous↗
PubMed1999

Virus levels in untreated African infants infected with human immunodeficiency virus type 1.

In developed areas, human immunodeficiency virus (HIV)-infected infants have high virus levels and rapidly progress to death. HIV levels were assessed in 1994-1997 in untreated infants in Malawi by analysis of dried blood spots tested by nucleic acid silica-bound amplification. Of 24 umbilical cord blood (CB)-positive samples, 83% had >10,000 copies/mL. The median virus level was 78,000 copies/mL. First positive sample median levels were 355,000 copies/mL among 52 perinatally infected infants and 130,000 copies/mL among 43 infants infected by breast-feeding. Virus levels were stable, and initial levels predicted levels 1 year after infection (P=.005), at which time levels did not significantly differ among in utero, perinatally, or postnatally infected infants. Thus, neither age at infection nor route of infection significantly influenced HIV levels measured 1 year after infection. Most (87%) CB-positive infants were infected before labor onset, since virus levels greatly exceeded those expected in their mothers.

Adult↗
PubMed1995

High-level expression of endogenous acid phosphatase inhibits growth and vectorial secretion in Saccharomyces cerevisiae.

The secretion pathway of Saccharomyces cerevisiae was challenged by constitutively overexpressing plasmid-encoded acid phosphatase, a secreted endogenous glycoprotein. A 2-microns-based multicopy plasmid carrying the coding sequence of acid phosphatase under the control of a truncated variant of the strong constitutive glyceraldehyde-3-phosphate dehydrogenase promoter was used for expression. Selection for the promoterless dLEU2 marker leads to a growth arrest. This is not per se due to leucine starvation, but due to intracellular accumulation of highly glycosylated enzymatically active acid phosphatase. Immunofluorescence and cytological analysis indicate that intracellular accumulation of acid phosphatase occurs in a subpopulation of cells. By Ludox-AM density centrifugation, these cells can be enriched on the basis of their higher density. The dense accumulating cells have a higher average plasmid copy number and produce more acid phosphatase than non-accumulating cells of low density. These cells are defective in directed secretion and bud formation, therefore can no longer grow and show dramatic changes in cell morphology. We suggest that the secretion pathway in these cells is overloaded with the high level of acid phosphatase leading to a shutdown in vectorial secretion, subsequently to a standstill in growth and to the intracellular accumulation of further expressed acid phosphatase. We have indications that accumulation of acid phosphatase occurs in the late Golgi, suggesting a limitation of the overall secretion at this stage.

Acid Phosphatase↗
PubMed1993

A comparative study of heel-stick devices for infant blood collection.

OBJECTIVE: To evaluate two heel-stick devices by comparing the volume of blood collected, blood sampling time, amount of hemolysis, pain inflicted during the procedure, and extent of bruising. DESIGN: Randomized trial. SETTING: Primary care center in a tertiary-level perinatal hospital. PARTICIPANTS: Forty healthy, full-term newborns with a postnatal age of greater than 24 hours. Newborns were fed no more than 1 1/2 hours before blood sample collection and fulfilled the requirement for routine phenylketonuria and thyroid screening. INTERVENTIONS: Newborns were allocated to a single stab with either an automated incision or a lancet puncture device. MEASUREMENTS/MAIN RESULTS: The total volume of blood and blood sampling time were significantly better with the automated incision device (P < .001). Hemolysis was also reduced with the automated incision device (P < .03). Plasma hemoglobin levels were below 1.0 g/L in all samples obtained with the automated incision device and in 71% of samples obtained with the lancet device. There were no differences in the extent of bruising or in pain symptoms manifested by mean increases in heart rate and percentage of time crying during the procedure. CONCLUSIONS: The larger volume of blood obtained within a shorter period for blood collection and reduced hemolysis with the automated incision device make it a preferred instrument for neonatal blood collection.

Birth Weight↗
PubMed1990

The influence of GAP promoter variants on hirudin production, average plasmid copy number and cell growth in Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae has been engineered to synthesize and secrete desulfato-hirudin (hirudin), a thrombin inhibitor from the leech Hirudo medicinalis. The synthetic gene coding for hirudin was expressed constitutively under the control of four size-variants of the yeast glyceraldehyde-3-phosphate dehydrogenase promoter (GAP) and cloned into a 2 mu based multicopy yeast vector. The constitutive action of the four promoter variants was confirmed by demonstrating that the expression and secretion of hirudin is growth-related. The different efficiencies of the promoter variants not only affected hirudin expression but also led to changes in several cellular parameters, such as cell growth, average plasmid copy number and plasmid stability. The observed changes show that yeast cells establish a specific equilibrium for each promoter variant. We conclude, that the adjustment of cellular parameters in response to the expression levels of a heterologous protein is regulated by two counteracting selective forces: (1) the need for complementation of the auxotrophic host marker by the plasmid-encoded selection gene which, in the case of dLEU2, requires several plasmid copies; and (2) a selective advantage of cells with a lower copy number enabling them to escape the burden of heterologous protein production.

Base Sequence↗
PubMed1986

Fc gamma-receptor-mediated changes in the plasma membrane potential induce prostaglandin release from human fibroblasts.

Binding of aggregated human immunoglobulin G (IgG) on diploid human fibroblasts leads to a rapid depolarization of the cells within 1-2 min. We resolved this membrane potential change into its plasma membrane and mitochondrial membrane components by measuring the transmembrane distribution of the lipophilic tritium-labelled cation tetraphenylphosphonium, [3H]Ph4P+. The responsibility of the plasma membrane for the membrane potential change, induced by binding of IgGs, is demonstrated. The IgG-induced membrane depolarization leads to the induction of prostaglandin E2 synthesis. Aggregated immunoglobulins (IgG) are specifically bound via the Fc portion because only binding of Fc fragments, in contrast to (Fab')2 fragments, leads to a stimulation of prostaglandin E2 synthesis comparable to that mediated by IgGs. Depolarization of the plasma membrane by short incubation of the fibroblasts in high-K+ buffer (5 min) results in a stimulation of prostaglandin E2 synthesis comparable to that mediated by either aggregated human IgGs or Fc fragments. Our previous results on Fc gamma-receptor-mediated antigen-IgG-antibody complex internalization showed that a maximum uptake of these complexes could be detected 60-90 min after binding. Therefore, we conclude that not internalisation but binding of aggregated IgGs to the Fc gamma receptors on human fibroblasts is the stimulus for plasma membrane depolarization leading to an enhanced prostaglandin E2 release.

Antigen-Antibody Complex↗
PubMed1982

Biosynthesis of mitochondrial porin and insertion into the outer mitochondrial membrane of Neurospora crassa.

Mitochondrial porin, the major protein of the outer mitochondrial membrane is synthesized by free cytoplasmic polysomes. The apparent molecular weight of the porin synthesized in homologous or heterologous cell-free systems is the same as that of the mature porin. Transfer in vitro of mitochondrial porin from the cytosolic fraction into the outer membrane of mitochondria could be demonstrated. Before membrane insertion, mitochondrial porin is highly sensitive to added proteinase; afterwards it is strongly protected. Binding of the precursor form to mitochondria occurs at 4 degrees C and appears to precede insertion into the membrane. Unlike transfer of many precursor proteins into or across the inner mitochondrial membrane, assembly of the porin is not dependent on an electrical potential across the inner membrane.

Chemical Phenomena↗