Have whales returned to a historical hotspot of industrial whaling? The pattern of southern right whale Eubalaena australis recovery at South Georgia

Around 176500 whales were killed in the sub-Antarctic waters off South Georgia (South Atlantic) between 1904 and 1965. In recent decades, whales have once again become summer visitors, with the southern right whale (SRW) the most commonly reported species until 2011. Here, we assess the distribution, temporal pattern, health status and likely prey of SRWs in these waters, combining observations from a summertime vessel-based expedition to South Georgia, stable isotope data collected from SRWs and putative prey and sightings reports collated by the South Georgia Museum. The expedition used directional acoustics and visual surveys to localise whales and collected skin biopsies and photo-IDs. During 76 h of visual observation effort over 19 expedition days, SRWs were encountered 15 times (~31 individuals). Photo-IDs, combined with publicly contributed images from commercial vessels, were reconciled and quality-controlled to form a catalogue of 6 fully (i.e. both sides) identified SRWs and 26 SRWs identified by either left or right sides. No photo-ID matches were found with lower-latitude calving grounds, but 3 whales had gull lesions supporting a direct link with Península Valdés, Argentina. The isotopic position of SRWs in the South Georgia food web suggests feeding on a combination of copepod and krill species. Opportunistic reports of SRW sightings and associated group sizes remain steady over time, while humpback whales provide a strong contrast, with increased sighting rates and group sizes seen since 2013. These data suggest a plateau in SRWs and an increasing humpback whale presence in South Georgia waters following the cessation of whaling.

Value of allohaemagglutinins in the diagnosis of a polysaccharide antibody deficiency

Polysaccharide antibody deficiency is characterized by a poor or absent antibody response after vaccination with an unconjugated pneumococcal polysaccharide vaccine. Allohaemagglutinins (AHA) are antibodies to A or B polysaccharide antigens on the red blood cells, and are often used as an additional or alternative measure to assess the polysaccharide antibody response. However, few studies have been conducted to establish the clinical significance of AHA. To investigate the value of AHA to diagnose a polysaccharide antibody deficiency, pneumococcal polysaccharide antibody titres and AHA were studied retrospectively in 180 subjects in whom both tests had been performed. Receiver operating characteristic curves for AHA versus the pneumococcal vaccine response as a marker for the anti-polysaccharide immune response revealed an area under the curve between 0·5 and 0·573. Sensitivity and specificity of AHA to detect a polysaccharide antibody deficiency, as diagnosed by vaccination response, were low (calculated for cut-off 1/4-1/32). In subjects with only low pneumococcal antibody response, the prevalence of bronchiectasis was significantly higher than in subjects with only low AHA (45·5 and 1·3%, respectively) or normal pneumococcal antibody response and AHA (2·4%). A logistic regression model showed that low pneumococcal antibody response but not AHA was associated with bronchiectasis (odds ratio 46·2). The results of this study do not support the routine use of AHA to assess the polysaccharide antibody response in patients with suspected immunodeficiency, but more studies are warranted to clarify the subject further.

Azole resistance in Aspergillus: an emerging problem?

Reports of Aspergillus' azole resistance are emerging, and resistance is now recognised as a cause of treatment failure. The scope of this article is to describe the problem of resistance in Aspergillus: the epidemiology, clinical impact and the underlying molecular mechanisms. In patients with acute invasive aspergillosis, the probability that the patient harbours a resistant strain depends on the emergence of resistant strains in the environment (acquired resistance due to CYP51A mutations and/or natural resistant Aspergillus species). As environmental pan-azole resistance of Aspergillus fumigatus is reported in increasing numbers in the Netherlands, surveillance is warranted. Voriconazole currently remains the first line therapeutic agent for invasive aspergillosis in Belgium. In chronic (and chronically treated) Aspergillus infections,"in-patient" resistance development is possible, especially in the setting of aspergilloma. Culturing an isolate during therapy should therefore be a trigger to test susceptibility.

Azole-resistant Aspergillus fumigatus due to TR46/Y121F/T289A mutation emerging in Belgium, July 2012

A new azole resistance mechanism in Aspergillus fumigatus consisting of a TR46/Y121F/T289A alteration in the cyp51A gene was recently described in the Netherlands. Strains containing these mutations are associated with invasive infection and therapy failure. This communication describes the first case of fatal invasive aspergillosis caused by TR46/Y121F/T289A outside the Netherlands, in the neighboring country of Belgium, suggesting geographical spread. TR46/Y121F/T289A leads to a recognisable phenotypic susceptibility pattern which should trigger cyp51A genotyping to monitor further spread.

Azole-resistant Aspergillus fumigatus due to TR46/Y121F/T289A mutation emerging in Belgium, July 2012

A new azole resistance mechanism in Aspergillus fumigatus consisting of a TR46/Y121F/T289A alteration in the cyp51A gene was recently described in the Netherlands. Strains containing these mutations are associated with invasive infection and therapy failure. This communication describes the first case of fatal invasive aspergillosis caused by TR46/Y121F/T289A outside the Netherlands, in the neighboring country of Belgium, suggesting geographical spread. TR46/Y121F/T289A leads to a recognisable phenotypic susceptibility pattern which should trigger cyp51A genotyping to monitor further spread.

Hepcidin as a biomarker for the diagnosis of iron metabolism disorders: a review

INTRODUCTION

Hepcidin plays a key role in the regulation of plasma iron levels through inhibition of iron export from enterocytes and macrophages. Hepcidin is considered a promising marker in the investigation of iron status, especially in patients that still pose a diagnostic challenge, such as infants and patients with chronic (kidney) disease.

OBJECTIVE

To critically review the current evidence for the diagnostic utility of hepcidin, including the (pre) analytical aspects in hepcidin determination.

SUMMARY

(Pre)analytical aspects--Since it is doubtful that the prohormone prohepcidin is a relevant biomarker, only the mature peptide hepcidin should be measured. Determinations of serum hepcidin are preferable, as the value of urine concentrations is still unclear. Method harmonization is needed since hepcidin values vary widely between methods. Several (pre-) analytical issues remain unanswered. These barriers hamper the investigation into the diagnostic value of hepcidin. Diagnostic utility--Hepcidin is an acute-phase reactant. The diagnostic potential of hepcidin is controversial in the different settings of iron deficiency as evidence is contradictory (anaemia of chronic disease) or limited (infants). In the setting of haemochromatosis, it has been suggested that hepcidin could be useful to stratify molecular testing, or to optimize the frequency of phlebotomies, but this remains to be investigated.

A trial of consent procedures for future research with clinically derived biological samples

Background:

The aims of this study were to determine which consent procedure patients prefer for use of stored tissue for research purposes and what the effects of consent procedures on actual consenting behaviour are.

Methods:

We offered 264 cancer patients three different consent procedures: ‘one-time general consent’ (asked written informed consent), ‘opt-out plus’ (had the opportunity to opt out by a form), or the standard hospital procedure (control group). The two intervention groups received a specific leaflet about research with residual tissue and verbal information. The control group only received a general hospital leaflet including opt-out information, which is the procedure currently in use. Subsequently, all patients received a questionnaire to examine their preferences for consent procedures.

Results:

In all, 99% of patients consented to research with their residual tissue. In the ‘one-time consent’ group 85% sent back their consent form. Patients preferred ‘opt-out plus’ (43%) above ‘one-time consent’ (34%) or ‘opt-out’ (16%), whereas 8% indicated that they did not need to receive information about research with residual tissues or be given the opportunity to make a choice.

Conclusions:

The ‘opt-out plus’ procedure, which places fewer demands on administrative resources than ‘one-time consent’, can also address the information needs of patients.

Opt-out plus, the patients' choice: preferences of cancer patients concerning information and consent regimen for future research with biological samples archived in the context of treatment

AIMS

The aims of this study were to determine: (1) which consent procedures patients prefer for future medical research with tissue stored following surgery; (2) the percentage of patients who choose not to provide consent for research with their stored tissue; (3) the reasons given for denying such tissue use.

METHODS

Patients (n = 103) from the Vrije Universiteit Medical Centre, an academic hospital in The Netherlands, who had recently undergone surgery for breast or colorectal cancer were mailed a questionnaire about preferences for consent regimens.

RESULTS

Seventy-six patients (74%) completed the questionnaire. Only two patients (3%) chose not to provide consent for research with their stored tissue. The majority of patients (60%) preferred an "opt-out plus" procedure that included receiving active, verbal information to "one-time general consent" (11%) or to an "opt-out" procedure without verbal notification (5%). Only 3% indicated a wish to be asked for consent for each new research project and 21% did not know what they preferred or had no preference. There were no significant associations observed between preference for the various consent regimens and age, sex, educational level or personal sense of ownership of the stored tissue.

CONCLUSION

Patients prefer an opt-out plus procedure that includes the provision of explicit, verbal and written information. Less than 5% of patients decline to consent to the use of their stored tissue for research purposes.

CRT screens may give rise to biased estimates of interhemispheric transmission time in the Poffenberger paradigm

It has been shown that computer video-display units do not emit luminance uniformly over the entire screen, but emit more light on the right hand side than on the left hand side. The present study investigates whether this luminance asymmetry has implications for the manual and vocal estimates of interhemispheric transmission time (IHTT) in the Poffenberger paradigm. In particular, it is shown that previous reports of right visual-field advantages for vocal responses are an artifact of the luminance asymmetry of computer screens and that this asymmetry also has implications for estimates of differences in transmission time from the right to the left hemisphere in manual responses. In addition, we examined the impact of stimulus intensity and dark adaptation to the IHTT estimates and found that neither had an effect. This is in line with previous evidence that interhemispheric transfer in the Poffenberger paradigm does not depend on the transfer of visual information.

Immune reactivity to mite allergens in nonatopic subjects: immune deviation or immune ignorance

Most subjects without IgE to Dermatophagoides pteronyssinus do not have IgG to Der p 1 or Der p 2 (as measured by RIA). However, by immunoblot or ELISA, IgG reactivity (mostly IgG1) to mite components is easily detectable. This discrepancy is caused largely by immune reactivity to mite components with a high molecular weight under native conditions (possibly mite gut flora cross-reactive with human gut flora) and partially by the presence of IgG with low affinity for fluid-phase antigen. We conclude that the pattern of IgG antibody in subjects without IgE to mites does not support the notion of immune deviation, but rather indicates a lack of a mite-induced high-affinity immune response.

Patients unaware of their HIV status present to inner city accident and emergency department with respiratory complications

OBJECTIVE

To examine the clinical presentations and management of patients presenting to an accident and emergency (A&E) department with an AIDS defining illness (ADI).

METHODS

Presentations of patients in the A&E department with ADI were reviewed retrospectively. The age, sex, ethnic origin, risk factor for HIV infection, route of referral to hospital, presenting complaint, triage category, referral from A&E, admission under medical specialists, diagnosis, and survival from ADI were noted for each patient.

RESULTS

133 patients were registered at St Mary's Hospital in London with ADI during 1994. A significant minority of these patients (25/133) presented to the hospital without prior knowledge of their HIV positive status. Thirty two patients presented to the A&E department with their ADI. Of these, 13/32 (41%) were unaware of the HIV serostatus. All 13 patients had an acute respiratory disease (Pneumocystis carinii pneumonia or pulmonary tuberculosis). In contrast, patients aware of their HIV positive status (19/32) presented to the A&E department with a wide range of non-pulmonary ADI.

CONCLUSIONS

The study emphasises the importance of respiratory complications in patients who present with a ADI to emergency departments but are unaware of their HIV positivity. These patients presented solely with Pneumocystis carinii pneumonia or pulmonary tuberculosis, conditions in which early diagnosis and treatment significantly reduce morbidity and mortality.

Effects of capsaicinoids on oxidative metabolism of caffeine in isolated rat hepatocytes

The metabolism of caffeine was studied in isolated rat hepatocytes, in the absence and presence of capsaicinoids. Caffeine and four primary metabolite fractions were identified by high performance liquid chromatography: 1,7-dimethylxanthine, 3,7-dimethylxanthine, 1,3-dimethylxanthine and 1,3,7-trimethyluric acid. The incubation with the lowest concentrations (0.1 and 1 microM) of capsaicinoids (natural extract, capsaicin, dihydrocapsaicin) showed a stimulatory effect on caffeine metabolism, which was further enhanced with capsaicin. At 10 microM, capsaicin stimulated the two pathways of metabolism of caffeine (N-demethylation and C-8 oxidation). In contrast, dihydrocapsaicin and the natural extract seem to inhibit the N-demethylation pathways without affecting the C-8 oxidation route. The inhibitory activity on the N-demethylation pathways and especially the N-7 demethylation pathway was pronounced at the first 30 min of incubation. These results suggest that the two pathways (N-demethylation and C-8 oxidation) are mediated by different isozymes of cytochromes P-450. This is in agreement with recent findings.

Immunocytochemical identification of DNA adducts, O6-methylguanine and 7-methylguanine, in respiratory and other tissues of rat, mouse and Syrian hamster exposed to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone

The present paper reports about an immunocytochemical inventory of the cell types involved in the metabolic activation of the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) to a DNA methylating metabolite. The formation and distribution of the methylated DNA bases O6-methylguanine (O6-meGua) and 7-methylguanine (7-MeGua) were studied in respiratory tissues, oesophagus, liver, kidneys, pancreas, small intestine, colon and prostate of rat, mouse and hamster 6 h after treatment with a single dose of 30 mg NNK/kg. The tissue- and cell-specific distribution of O6-meGua- and 7-meGua-specific nuclear staining showed the same patterns and were remarkably similar in rat, mouse and hamster in spite of the diverging spectra of NNK-induced tumours in these species. In nasal tissue, a target for NNK-induced tumourigenesis in rat and hamster, but not in mouse, adduct-specific nuclear staining was observed in all three species in sustentacular cells, Bowman glands, respiratory epithelial cells and serous glands. Both methylated DNA bases were also observed in basal cells of the olfactory epithelium of rat and (occasionally) hamster, but not in those of the mouse. In the trachea, a target for NNK-induced tumourigenesis in hamster only, substantial adduct-specific nuclear staining was found in basal epithelial and glandular cells of the hamster; in the same cells of rat and mouse only a weak nuclear staining was found. In the lung, a common target for NNK-induced tumourigenesis, the formation of O6-meGua and 7-meGua was restricted predominantly to bronchial and proximal bronchiolar epithelium. Nuclear staining in the rat was occasionally found in alveolar cells and was also observed in hepatocytes. In the three species investigated, O6-meGua- and 7-MeGua-specific nuclear staining was found in target and non-target tissues. Apparently, and in analogy with results obtained in other studies, the species-specific organotropy for tumour formation of NNK is not exclusively determined by DNA methylation. Expanding methylation data with literature data on factors considered to be involved in tumour formation, namely proliferation, toxicity and DNA repair among others, still did not lead to a satisfactory explanation for the species-specific organotropy observed. Additional factors (yet to be identified), need to be taken into account in order to explain (and predict) tumourigenic effects induced by monofunctional methylating agents.

Accumulation of O6- and 7-methylguanine in DNA of N-nitroso-N-methylbenzylamine-treated rats is restricted to non-target organs for N-nitroso-N-methylbenzylamine-induced carcinogenesis

The distribution and accumulation of O6-methylguanine (O6-meGua) and 7-methylguanine (7-meGua) was investigated immunocytochemically in target and non-target tissues of rats injected twice weekly with 0.5 mg N-nitroso-N-methylbenzylamine (NMBzA)/kg for 16.5 weeks. Seventy two hours after every two or three doses, two NMBzA-treated rats and one control rat were killed. Tissue-specific cell proliferation was investigated after two injections of bromodeoxyuridine (BrdU) to rats unexposed to NMBzA. Neither O6-meGua- nor 7-meGua-specific immunostaining could be observed in the target tissues for tumor induction, i.e. esophagus, tongue and forestomach. Accumulation of both O6-meGua and 7-meGua was found, however, in nasal, tracheal and bronchiolar epithelia and glands--tissues for which tumor induction by NMBzA has not been reported. An explanation for this phenomenon might be the relatively low levels of cellular proliferation we observed in the latter epithelia. The present results support the hypothesis that the tumorigenic organotropism of NMBzA is determined both by the level of DNA methylation and the proliferative capacity of the methylated cells.

Immunocytochemical localization of DNA adducts induced by a single dose of N-nitroso-N-methylbenzylamine in target and non-target tissues of tumor formation in the rat

The formation and short-term persistence of O6-methylguanine (O6-meGua) and 7-methylguanine (7-meGua) in individual cells of various target and non-target tissues for tumor induction in rats were examined after a single dose of N-nitroso-N-methylbenzylamine (NMBzA). In the principal target organ, the esophagus, both adducts were observed at 6 h after 0.5, 1.0 and 2.5 mg NMBzA/kg in a dose-dependent manner in nuclei of epithelial cells only. Nuclear staining in this organ had apparently declined by 72 h and modified nuclei were found in the more differentiated cells located closer to the lumen. In epithelial cells of the tongue, another target organ of NMBzA, methylation at 6 h was also dose dependent. At 72 h nuclear staining was lower and again largely located in differentiated cells. In the liver, a non-target organ, O6-meGua was not detectable and 7-meGua-specific staining was weak, being only observed at 6 h after the highest dose. Dose-dependent DNA methylation was seen, both at 6 and 72 h, in other non-target organs such as lung (bronchiolar epithelial cells), trachea (epithelial and glandular cells) and nasal cavity (respiratory epithelial cells, ductal cells of the respiratory lamina propria and cells of Bowman glands of the olfactory lamina propria); the nuclei of the glandular cells were highly methylated. Visual inspection of lung, trachea and nasal cavity indicated no or only minor losses of O6-meGua and 7-meGua between 6 and 72 h. Microdensitometric determination of the nuclear staining at 6 and 72 h indicated that the promutagenic O6-meGua was partially lost from cells of the tongue epithelium but did persist in esophageal epithelial cells; 7-meGua was lost to a substantial extent from both tongue and esophagus. The present results imply that the organotropism of NMBzA is not uniquely determined either by the initial level or the short-term persistence of DNA methylation.

Determination of debrisoquine and metabolites in human urine by gas chromatography-mass spectrometry

A gas chromatographic-mass spectrometric analysis has been developed for the determination of debrisoquine and its metabolites in the urine of healthy individuals (controls) and patients with chronic renal failure. The sensitive and specific assay comprises selected-ion monitoring of the drug and the metabolites 4-hydroxydebrisoquine and 8-hydroxydebrisoquine using guanoxan as the internal standard. The limit of detection is ca. 0.2 microgram/ml. The clinical study shows that the healthy individuals and patients with chronic renal failure can be divided in two groups of extensive metabolizers and poor metabolizers, respectively. The extensive metabolizers excreted large amounts of 4-hydroxydebrisoquine and minor amounts of 8-hydroxydebrisoquine. The poor metabolizers excreted small amounts of 4-hydroxy metabolite, and no 8-hydroxydebrisoquine was detected in the urine.

Activation of c-K-ras is frequent in pancreatic carcinomas of Syrian hamsters, but is absent in pancreatic tumors of rats

We have investigated the presence of mutations in ras genes at codons 12, 13 and 61 in chemically induced pancreatic tumors of rats and Syrian hamsters. Mutations were detected by means of allele-specific oligonucleotide hybridization to ras sequences amplified in vitro by the polymerase chain reaction. No mutations were observed in the c-K-ras gene or the c-H-ras gene of nine azaserine-induced adenomas and 15 carcinomas of the rat pancreas. This indicates that activated ras genes are not commonly involved in rat pancreatic cancer evolving from acinar cells. However, in 19 out of 20 ductular adenocarcinomas of hamster pancreas (95%), either codon 12 or 13 of the c-K-ras gene was mutated. This indicates that the activation of c-K-ras is a frequent event in the multistep process of pancreatic carcinogenesis induced by the alkylating carcinogen N-nitrosobis(2-oxopropyl)amine (BOP). The mutations of both codons were G----A transitions of the second base which is consistent with the type of mutation to be expected from DNA alkylation. Activation of the c-K-ras gene, therefore, may not only be a frequent but also an early event in hamster pancreas carcinogenesis. The frequent activation of the c-K-ras gene in both human and hamster pancreatic cancer emphasizes the relevance of BOP-induced pancreatic adenocarcinomas in Syrian hamsters as an experimental model system for studying human pancreatic cancer.

Pharmacokinetics of melatonin in man after intravenous infusion and bolus injection

The pharmacokinetics of melatonin during the day-time has been studied in 4 healthy subjects after a bolus i.v. injection of 5 or 10 micrograms/person and after a 5 h infusion of 20 micrograms per person in 6 healthy subjects. In addition, a pinealomectomized patient whose nocturnal plasma melatonin had been abolished was investigated after the i.v. infusion--once during the night and once during the day. The clearance of melatonin from blood showed a biexponential decay. The pharmacokinetic parameters in the two studies were similar, except for the disappearance rate constant beta and the apparent volume of distribution at steady-state (Vss). Supplementary peaks or troughs were superimposed on the plateau and the falling part of the profile. They were not due to stimulation of endogenous secretion, because they were also seen in the pinealomectomized patient. During the melatonin infusion, the plasma hormone level reached a steady-state after 60 and 120 min, and when it was equal to the nocturnal level. The infusion regime may be valuable in replacing blunted hormonal secretion in disease states.

Immunocytochemical analysis of O6-alkylguanine shows tissue specific formation in and removal from esophageal and liver DNA in rats treated with methylbenzylnitrosamine, dimethylnitrosamine, diethylnitrosamine and ethylnitrosourea

The formation and repair of carcinogen-DNA adducts in esophagus and liver of rats treated with a single i.p. dose of methylbenzylnitrosamine (MBN), dimethylnitrosamine (DMN), diethylnitrosamine (DEN) or ethylnitrosourea (ENU) has been studied using peroxidase immunocytochemistry to visualize O6-alkylguanine in DNA of individual cells. After MBN O6-methylguanine (O6-MeG) specific nuclear staining was only present in the target tissue for tumor induction, the esophageal epithelium. Part of the adducts persisted for at least 72 h. No O6-MeG could be detected in liver. DEN, a carcinogen in liver and esophagus, led to DNA modification of esophageal epithelial cells, and liver parenchymal and non-parenchymal (Kupffer and sinusoidal) cells of the centrilobular area. O6-EtG was removed within 72 h from both liver cell populations. A similar distribution of adduct (O6-MeG) formation was observed in liver after the hepatocarcinogen DMN, but this nitrosamine did not detectably modify esophageal cells. O6-MeG persisted in Kupffer and especially sinusoidal lining cells of liver, consistent with the induction of sarcomas by DMN. The relatively unspecific, directly alkylating carcinogen ENU modified DNA of all cell types to a similar extent. A qualitative correlation was obtained between the tissue specific ability to induce tumors and the formation of O6-alkylguanine (O6-alkylG). Our experiments support the hypothesis that DNA modification is necessary for the initiation of carcinogenesis by chemical carcinogens, and that a low capacity to repair promutagenic lesions, like O6-alkylG, potentiates this process.

Nocturnal continuous infusion of growth hormone (GH)-releasing hormone results in a dose-dependent accentuation of episodic GH secretion in normal men

Fluctuations in plasma GH levels have been found in patients with acromegaly who have continuously elevated levels of ectopically produced GH-releasing hormone (GHRH). Likewise, plasma GH fluctuations have been found in normal subjects receiving continuous GHRH infusions. We report the effects of two doses of GHRH, administered by constant infusion, on nocturnal GH secretion in six normal young men. Each received, in random order, 2.5 ng/kg X min GHRH, 15 ng/kg X min GHRH, and 0.15 M NaCl. During both GHRH doses, a highly significant increase in total nocturnal GH secretion was found (P less than 0.001) as well as an increase in GH secretion during different periods of the night. Nocturnal GH secretion was episodic during the GHRH infusions, with an increase in the number and magnitude of the peaks compared to those during the NaCl infusion. Plasma immunoreactive GHRH concentrations plateaued at 1 h during the high dose and at 3 h during the low dose GHRH infusion. Sleep parameters, including total sleep time, sleep latency, and duration and timing of the different sleep stages, were not affected by GHRH infusions. We conclude that GHRH, continuously infused, increases nocturnal GH secretion according to the dose, while the episodic pattern of GH secretion is maintained.

Pituitary stimulation by combined administration of four hypothalamic releasing hormones in normal men and patients

Ten normal young men (22-28 yr of age), within 10% of their ideal body weight, were given the four releasing hormones (TRH, 200 micrograms; GnRH, 100 micrograms; ovine corticotropin-releasing hormone, 50 micrograms; GH-releasing hormone, 80 micrograms) iv on separate days and then in combination on the same day. Plasma TSH, PRL, FSH, LH, cortisol, ACTH, and GH were measured by RIA in samples collected from 20 min before to 120 min after injection. There were no significant differences in responses to the separate and combined tests for FSH, LH, cortisol, ACTH, and GH. The plasma TSH (0.001 less than P less than 0.01) and PRL (P less than 0.001) responses were significantly higher after the combined test. The tolerance was identical to that of TRH alone. In eight patients studied after pituitary surgery, combined administration provided results comparable to those obtained after separate administration of TRH, GnRH, and insulin.

The assessment and significance of habituation to a repeated stimulus by the human fetus

Habituation is the progressive decrease in response by an organism when it is stimulated repeatedly. This process is a basic form of learning and a normal pattern may be one indication of intact central nervous system function. This study assessed habituation of a behavioral response by the human fetus to repeated vibrotactile stimuli. Of the 40 normal fetuses studied 37 habituated after 10 to 50 stimuli. The gestational age at which the fetus first responded to the stimulus ranged from 22 to 30 weeks. Female fetuses responded 2 weeks earlier than males. The possible value of this assessment in obstetrical practice is presented.

Fetal habituation in high-risk pregnancies

Habituation is a basic form of learning and probably requires an intact central nervous system. Habituation in the behavioural response to vibration in 40 normal human fetuses was compared with that in a group of high-risk pregnancies with an increased risk of fetal neurological damage. Highly significant differences in habituation patterns between the high-risk groups and normal control subjects were found. This test may offer a method of assessing the integrity of the fetal central nervous system.