Clinical pharmacology of exogenously administered alkaline phosphatase

PURPOSE

To evaluate the clinical pharmacology of exogenous alkaline phosphatase (AP).

METHODS

Randomized, double-blind, placebo-controlled sequential protocols of (1) ascending doses and infusion duration (volunteers) and (2) fixed dose and duration (patients) were conducted at clinical pharmacology and intensive care units. A total of 103 subjects (67 male volunteers and 36 patients with severe sepsis) were administered exogenous, 10-min IV infusions (three ascending doses) or 24-72 h continuous (132.5-200 U kg(-1) 24 h(-1)) IV infusion with/without preceding loading dose and experimental endotoxemia for evaluations of pharmacokinetics, pharmacodynamics, safety parameters, antigenicity, inflammatory markers, and outcomes.

RESULTS

Linearity and dose-proportionality were shown during 10-min infusions. The relatively short elimination half-life necessitated a loading dose to achieve stable enzyme levels. Pharmacokinetic parameters in volunteers and patients were similar. Innate immunity response was not significantly influenced by AP, while renal function significantly improved in sepsis patients.

CONCLUSIONS

The pharmacokinetics of exogenous AP is linear, dose-proportional, exhibit a short half-life, and are not influenced by renal impairment or dialysis.

[Deferred consent for inclusion of patients unable to give their consent in studies in the field of emergency medicine]

Respect for individual autonomy, expressed in the concept of informed consent, is a basic principle in research with humans. Many patients in intensive care are unable to give consent because of mental incapacity, and this can be further complicated in emergency research, in which the treatment or experiment needs to be initiated without delay. In those situations consent can be deferred. Randomization is done without prior consent, followed by patients' or relatives' consent at a later stage. Butwhat should one do with the data if the patient dies at an early stage after randomization before consent could be obtained? Should the data be used or not? Should the relatives be asked for consent for using the data? The Dutch Central Committee on Research involving Human Subjects (CCMO) states that asking for consent after the patient has died makes no sense, because with the death of the patient the research has ended. Relatives do not have the authority to give consent for the use of medical data after the patient has died. Data can be used anonymously in the final analysis of the trial. We propose a flowchart for this procedure.

Expression of two functionally distinct plant endo-beta-1,4-glucanases is essential for the compatible interaction between potato cyst nematode and its hosts

For the proliferation of their feeding sites (syncytia), the potato cyst nematode Globodera rostochiensis is thought to recruit plant endo-beta-1,4-glucanases (EGases, EC. 3.2.1.4). Reverse-transcription polymerase chain reaction experiments on tomato (Solanum lycopersicum) indicated that the expression of two out of the at least eight EGases, namely Sl-cel7 and Sl-cel9C1, is specifically upregulated during syncytium formation. In situ hybridization and immunodetection studies demonstrated that both EGases are specifically expressed inside and adjacent to proliferating syncytia. To assess the importance of Sl-cel7 and Sl-cel9C1 for nematode development, we decided to knock them out individually. Sl-cel9C1 probably is the only class C EGase in tomato, and we were unable to regenerate Sl-cel9C1-silenced plants. Potato (S. tuberosum), a close relative of tomato, harbors at least two class C EGases, and St-cel7-or St-cel9C1-silenced potato plants showed no obvious aberrant phenotype. Infection with potato cyst nematodes resulted in a severe reduction of the number of adult females (up to 60%) and a sharp increase in the fraction of females without eggs (up to 89%). Hence, the recruitment of CEL7, an enzyme that uses xyloglucan and noncrystalline cellulose as natural substrates, and CEL9C1, an enzyme that uses crystalline cellulose, is essential for growth and development of potato cyst nematodes.

Activational effects of estradiol and dihydrotestosterone on social recognition and the arginine-vasopressin immunoreactive system in male mice lacking a functional aromatase gene

In rodents, parts of the arginine-vasopressin (AVP) neuronal system are sexually dimorphic with males having more AVP-immunoreactive cells/fibers than females. This neuropeptide neuronal system is highly sensitive to steroids and has been proposed to play an important role in the processing of olfactory cues critical to the establishment of a social memory. We demonstrate here that gonadally intact male aromatase knockout (ArKO) mice, which cannot aromatize androgens into estrogens due to a targeted mutation in the aromatase gene, showed severe deficits in social recognition as well as a reduced AVP-immunoreactivity in several brain regions. To determine whether this reduction is due to a lack of organizational or activational effects of estrogens, we assessed social recognition abilities and AVP-immunoreactivity in male ArKO and wild-type (WT) mice when treated with estradiol benzoate (EB) in association with dihydrotestosterone propionate (DHTP) in adulthood. Adult treatment with EB and DHTP restored social recognition abilities in castrated ArKO males since they showed normal female-oriented ultrasonic vocalizations and were able to recognize an unfamiliar female using a habituation-dishabituation paradigm. Furthermore, adult treatment also restored AVP-immunoreactivity in the lateral septum of ArKO males to levels observed in intact WT males. These results suggest that social recognition in adulthood and stimulation of AVP expression in the adult mouse forebrain depend predominantly on the estrogenic metabolite of testosterone. Furthermore, our results are in line with the idea that the organization of the AVP system may depend on androgen or sex chromosomes rather than estrogens.

Anticipation of distress after discontinuation of mechanical ventilation in the ICU at the end of life

BACKGROUND

A considerable number of patients admitted to the intensive care unit (ICU) die following withdrawal of mechanical ventilation. After discontinuation of ventilation without proper preparation, excessive respiratory secretion is common, resulting in a 'death rattle'. Post-extubation stridor can give rise to the relatives' perception that the patient is choking and suffering. Existing protocols lack adequate anticipatory preparation to respond to all distressing symptoms.

METHODS

We analyzed existing treatment strategies in distressing symptoms after discontinuation of mechanical ventilation.

CONCLUSION

The actual period of discontinuation of mechanical ventilation can be very short, but thoughtful anticipation of distressing symptoms takes time. There is an ethical responsibility to anticipate and treat (iatrogenic) symptoms such as pain, dyspnea-associated respiratory distress, anxiety, delirium, post-extubation stridor, and excessive broncho-pulmonary secretions. This makes withdrawal of mechanical ventilation in ICU patients a thoughtful process, taking palliative actions instead of fast terminal actions. We developed a flowchart covering all possible distressing symptoms that can occur after withdrawal of mechanical ventilation and extubation. We recommend a two-phase process. Six hours before extubation, enteral feeding should be stopped and parenteral fluids reduced, overhydrated patients should be dehydrated with furosemide, administration of sedatives (for distress) and opioids (for pain and/or dyspnea) should be continued or started and methylprednisolone should be given in anticipation of stridor after extubation. Thirty minutes before extubation, Butylscopolamine should be given and methylprednisolone repeated. After this the patient should be extubated to secure a dying process as natural as possible with the lowest burden due to distress.

Mining the secretome of the root-knot nematode Meloidogyne chitwoodi for candidate parasitism genes

Parasite proteins secreted at the interface of nematode and host are believed to play an essential role in parasitism. Here, we present an efficient pipeline of bio-informatic algorithms and laboratory experiments to identify candidate parasitism genes within nematode secretomes, i.e. the repertoire of secreted proteins in an organism. We performed our approach on 12 218 expressed sequence tags (ESTs) originating from three life stages of the plant parasitic nematode Meloidogyne chitwoodi--a molecularly unexplored root-knot nematode species. The ESTs from M. chitwoodi were assembled into 5880 contigs and open reading frames translated from the consensus sequences were searched for features of putative signal peptides for protein secretion and trans-membrane regions, resulting in the identification of 398 secretome members. The products of parasitism genes are secreted by a range of organs, including the oesophageal, amphidial and rectal glands, the intestine, and the hypodermis. To localize the site of expression in M. chitwoodi, we subjected the most abundant secretome members to in situ hybridization microscopy. We found hybridization of one tag in the dorsal oesophageal gland, seven in the two subventral oesophageal glands, two in the intestine and one tag hybridized to the tail tip in the proximity of the phasmids. Four sequences showed similarity to putative parasitism genes from other nematode species, whereas seven represented pioneering sequences. Our approach presents an efficient method to identify candidate parasitism genes, which does not require sophisticated cDNA isolation and selection protocols, and can therefore be used as a powerful starting point for the molecular investigation of parasites.

Efficacy of patient selection strategies for carotid endarterectomy by contrast-enhanced MRA on a 1 T machine and duplex ultrasound in a regional hospital

AIM

To investigate whether contrast-enhanced magnetic resonance angiography (CE-MRA) and duplex ultrasound (DUS) could replace digital subtraction angiography (DSA) for diagnosing internal carotid artery (ICA) stenosis in regional centres with less specialized technicians and equipment, such as a 1 Tesla MRI machine.

MATERIALS AND METHODS

Sixty-six consecutive, symptomatic patients with ICA stenosis, as evidenced using DSA, were included. In the first 34 patients DUS was validated and cut-off criteria were established. Data were analysed by receiver operating characteristic curve and logistic regression. Two observers analysed the DUS and CE-MRA results of 32 patients. Stenoses were categorized in accordance with North American Symptomatic Endarterectomy Trial (NASCET) measurement criteria.

RESULTS

Peak systolic velocity (PSV) in the ICA was defined as a better parameter for defining stenosis than end diastolic velocity and the PSV ICA:common carotid artery ratio. The optimal PSV threshold was 230cm/s. Four ICAs were not interpretable on DUS, and one on CE-MRA. Two patients did not undergo CE-MRA. The sensitivities and specificities were calculated: for DUS these were 100% and 68% respectively; for observer 1 on CE-MRA these were 93% and 89%, respectively; for observer 2 these were 92% and 87%, respectively. The sensitivity and specificity for combined DUS/CE-MRA were 100% and 85%, respectively. Seventy-eight percent of CE-MRA and DUS correlated. The weighted Kappa for CE-MRA and DSA were 0.8 and 0.9, respectively.

CONCLUSION

DUS and CE-MRA are effective non-invasive methods for selecting patients with ICA stenosis for carotid endarterectomy in non-specialized centres using a 1T machine. The present results suggest that no referrals to more specialized centres for non-invasive diagnostic work-up for carotid artery stenoses will be necessary.

The first demonstration of lactic acid in human blood in shock by Johann Joseph Scherer (1814-1869) in January 1843

Lactic acid was first found and described in sour milk by Karl Wilhelm Scheele (1742–1786) in 1780. The German physician–chemist Johann Joseph Scherer (1841–1869) demonstrated the occurrence of lactic acid in human blood under pathological conditions in 1843 and 1851. In this article we honour the forgotten observations by Scherer and describe the influence of Scherer's finding on further research on lactic acid at the end of the 19th century. We conclude that Scherer's 1843 case reports should be cited as the first description of lactic acid in human blood after death and also as the first demonstration of lactic acid as a pathological finding in septic and haemorrhagic shock. Carl Folwarczny was, in 1858, the first to demonstrate lactic acid in blood in a living patient.

Comparison of urinary odor-induced glomerular activation in the main olfactory bulb of aromatase knock-out and wild type female mice

Previously [D.W. Wesson, M. Keller, Q. Douhard, M.J. Baum, J. Bakker, Enhanced urinary odor discrimination in female aromatase knockout mice, Horm. Behav. 49 (2006) 580-586] female aromatase knock out mice successfully learned to discriminate in a food-motivated go/no-go task between urinary volatiles from ovariectomized female mice treated with estradiol as opposed to estradiol plus progesterone whereas wild type females failed to learn this odor discrimination. We asked whether this behavioral difference is reflected in the ability of these two types of urinary volatiles to differentially stimulate Fos expression in juxtaglomerular cells (an index of glomerular activation) of the main olfactory bulb (MOB) in wild type versus ArKO female mice. Statistically significant differences in the profiles of MOB glomerular activation were seen in ovariectomized, estrogen-treated ArKO as well as WT female subjects following exposure to urinary volatiles from ovariectomized females given estradiol alone as opposed to estradiol plus progesterone. Therefore, previously observed differences between females of the two genotypes in their behavioral responses to these odors must reflect differential processing in more central segments of the olfactory pathway instead of in the MOB.

Structural and functional characterization of a novel, host penetration-related pectate lyase from the potato cyst nematode Globodera rostochiensis

SUMMARY The cell wall, a strong extraprotoplasmic layer surrounding plant cells that mainly consists of a variety of polysaccharides, constitutes a major barrier for potential parasites. Plant-parasitic nematodes are well equipped to overcome this barrier as they produce and secrete cell-wall-degrading enzymes. Expression profiling of various life stages of the potato cyst nematode Globodera rostochiensis revealed a novel pectate lyase gene (Gr-pel2, 759 bp). The Gr-PEL2 protein showed highest similarity to pectate lyases from the facultative plant-parasitic nematodes Bursaphelenchus mucronatus and B. xylophilus and the soil-inhabiting saprophytic Streptomyces and Frankia species (i.e. 40-42% identity and 58-60% similarity), whereas only a remote relatedness to the previously identified Gr-PEL1 was observed (i.e. 28% identity and 43% similarity). Transient expression of Gr-pel2 in leaves of Nicotiana benthamiana resulted in severe malformations of the infiltrated tissues, not relating to maceration and soft rot symptoms. Ca(2+) is known to be essential for pectate lyase activity, and the most likely calcium-binding site was identified in the Gr-PEL2 protein by combining homology modelling of the three-dimensional structure, site-directed mutagenesis and transient expression in leaves. A highly charged cleft in Gr-PEL2, which is likely to be involved in substrate binding and which is also significantly more hydrophobic in Gr-PEL1, was shown to be essential for protein activity. Our results underline the broad spectrum of pectate lyases and cell-wall-degrading enzymes necessary for successful parasitism by cyst nematodes.

Exposure to oestrogen prenatally does not interfere with the normal female-typical development of odour preferences

The neural mechanisms controlling mate recognition and heterosexual partner preference are sexually differentiated by perinatal actions of sex steroid hormones. We previously showed that the most important action of oestrogen during prenatal development is to defeminise and, to some extent, masculinise brain and behaviour in mice. Female mice deficient in alpha-foetoprotein (AFP) due to a targeted mutation in the Afp gene (AFP-KO) do not show any female sexual behaviour when paired with an active male because they lack the protective action of AFP against maternal oestrogens. In the present study, we investigated whether odour preferences, another sexually differentiated trait in mice, are also defeminised and/or masculinised in AFP-KO females due to their prenatal exposure to oestrogens. AFP-KO females of two background strains (CD1 and C57Bl/6j) preferred to investigate male over female odours when given the choice between these two odour stimuli in a Y-maze, and thus remained very female-like in this regard. Thus, the absence of lordosis behaviour in these females cannot be explained by a reduced motivation of AFP-KO females to investigate male-derived odours. Furthermore, the presence of a strong male-directed odour preference in AFP-KO females suggests a postnatal contribution of oestrogens to the development of preferences to investigate opposite-sex odours.

Use of serological assays for diagnosis of hepatitis E virus genotype 1 and 3 infections in a setting of low endemicity

Because of the occurrence of genotype 3 hepatitis E virus (HEV) in regions of low endemicity, it is important to validate the currently used serological assays for diagnosing infections with viruses belonging to this lineage, since these assays only use antigens derived from genotype 1 and 2 viruses. We evaluated the Genelabs enzyme-linked immunosorbent assay (ELISA) and the RecomBlot from Mikrogen for the detection of HEV-specific immunoglobulin M (IgM) and IgG under conditions of low endemicity. We compared test results of 16 patients with locally acquired genotype 3 HEV, 8 genotype 1 patients, 167 healthy controls from the general population, and 101 cases with hepatitis due to other viral causes. The measured specificities of the ELISA (98%) and the RecomBlot (97%) were comparable to those given by the manufacturer for IgM but were significantly lower for IgG (93% by ELISA and 66% by immunoblotting, versus reported values of 98% for ELISA and 95% for blotting). Antibody levels detected following infections with genotype 3 were lower than those following genotype 1 infections except for those measured in the IgM ELISA. Reactivity to the four antigens used in the immunoblot assay were analyzed and showed differences in the IgM immunoblot reactions between genotype 1 patients and genotype 3 patients. The ORF3 antigen was the most specific antigen. The specificity could be improved by a combined testing regimen with confirmation by immunoblotting of all positive ELISA results and by raising the cutoff of the IgG immunoblot assay without loss of sensitivity. We conclude that a combination of ELISA and immunoblotting is needed for acceptable specificity and sensitivity of HEV assays under conditions of low endemicity.

Swine-like hepatitis E viruses are a cause of unexplained hepatitis in the Netherlands

Hepatitis E virus (HEV) infections in developed countries are recognized as an imported disease related to travel to endemic regions. However, increasing evidence suggests that HEV infection may also occur in the developed countries and that swine may act as a possible reservoir. To investigate the indigenous transmission of HEV in the Netherlands, sera from 50 blood donors and 1027 sera from patients with acute hepatitis were screened with an ELISA for HEV-specific IgG and IgM. Because the Netherlands is considered a nonendemic region, all positive ELISA results were confirmed by immunoblot to exclude false-positive results. Evidence of recent HEV infection was detected in 0% of the blood donors and 4.4% of the cases, based on combined positive IgM and IgG responses. The serodiagnosis was confirmed by a positive polymerase chain reaction (PCR) in 24 patients with hepatitis (2.3% overall, 51% of confirmed IgM+/IgG+ cases). IgG antibodies alone were detected in 4.2% of patients. We found related sequences to virus strains detected in Dutch pigs (genotype 3, 91-97% homology) in 89% of PCR-confirmed HEV patients. The detection of unique swine-like HEV sequences in 16 indigenous hepatitis patients without a recent travel history suggests that HEV is endemic in the Netherlands. We recommend including HEV tests in unexplained acute hepatitis patients, despite their travel history.