Cytosolic replication in epithelial cells fuels intestinal expansion and chronic fecal shedding of Salmonella Typhimurium

Persistent and intermittent fecal shedding, hallmarks of Salmonella infections, are important for fecal-oral transmission. In the intestine, Salmonella enterica serovar Typhimurium (STm) actively invades intestinal epithelial cells (IECs) and survives in the Salmonella-containing vacuole (SCV) and the cell cytosol. Cytosolic STm replicate rapidly, express invasion factors, and induce extrusion of infected epithelial cells into the intestinal lumen. Here, we engineered STm that self-destruct in the cytosol (STm^CytoKill), but replicates normally in the SCV, to examine the role of cytosolic STm in infection. Intestinal expansion and fecal shedding of STm^CytoKill are impaired in mouse models of infection. We propose a model whereby repeated rounds of invasion, cytosolic replication, and release of invasive STm from extruded IECs fuels the high luminal density required for fecal shedding.

Bacterial protein domains with a novel Ig-like fold target human CEACAM receptors

Streptococcus agalactiae, also known as group B Streptococcus (GBS), is the major cause of neonatal sepsis in humans. A critical step to infection is adhesion of bacteria to epithelial surfaces. GBS adhesins have been identified to bind extracellular matrix components and cellular receptors. However, several putative adhesins have no host binding partner characterised. We report here that surface‐expressed β protein of GBS binds to human CEACAM1 and CEACAM5 receptors. A crystal structure of the complex showed that an IgSF domain in β represents a novel Ig‐fold subtype called IgI3, in which unique features allow binding to CEACAM1. Bioinformatic assessment revealed that this newly identified IgI3 fold is not exclusively present in GBS but is predicted to be present in adhesins from other clinically important human pathogens. In agreement with this prediction, we found that CEACAM1 binds to an IgI3 domain found in an adhesin from a different streptococcal species. Overall, our results indicate that the IgI3 fold could provide a broadly applied mechanism for bacteria to target CEACAMs.

Foodborne infection of mice with Salmonella Typhimurium

The bacterial pathogen Salmonella enterica serovar Typhimurium is one of the most common causes of foodborne disease in humans and is also an important model system for bacterial pathogenesis. Oral inoculation of C57Bl/6 mice, which are genetically susceptible to Salmonella, results in systemic infection but the murine intestine is not efficiently colonized unless the intestinal microbiota is disrupted. Pretreatment of C57Bl/6 mice with streptomycin, followed by oral inoculation with Salmonella Typhimurium results in colitis resembling human intestinal Salmonellosis. The predominant method of delivery of bacteria is oral gavage, during which organisms are deposited directly into the stomach via a feeding needle. Although convenient, this method can be stressful for mice, and may lead to unwanted tracheal or systemic introduction of bacteria. Here, we developed a method for oral infection of mice by voluntary consumption of regular mouse chow inoculated with bacteria. Mice readily ate chow fragments containing up to 10⁸ CFU Salmonella, allowing for a wide range of infectious doses. In mice pretreated with streptomycin, infection with inoculated chow resulted in reproducible infections with doses as low as 10³ CFU. Mice not treated with streptomycin, as well as resistant Nramp1 reconstituted C57Bl/6J mice, were also readily infected using this method. In summary, voluntary consumption of chow inoculated with Salmonella represents a natural route of infection for foodborne salmonellosis and a viable alternative to oral gavage.

Thyroid hormones and the adrenergic nervous system

This paper reviews the various possible relationships between thyroid hormones and the adrenergic nervous system. These concern the sympathetic influence on thyroid hormone secretion, thyroid hormone - induced changes of sympathetic activity or adrenoceptor changes - the effects of catecholamines on thyroid hormone metabolism and, finally, the clinical benefits of beta-adrenoceptor blocking drugs on symptoms and signs of hyperthyroidism.

Antihypertensive and metabolic effects of increasing doses of atenolol and labetalol. A comparative study in primary hypertension

Thirty-two patients with primary hypertension were studied in a double-blind cross-over comparison between the cardioselective beta 1-blocking agent atenolol and the combined alpha- and beta-blocking agent labetalol. The doses used were atenolol 50--150 mg twice daily and labetalol 200--600 mg twice daily. Both drugs effectively reduced blood pressure and heart rate. Dose increments every second week resulted in a higher proportion of patients with normal blood pressure (les than or equal to 150/90 mm Hg) with both drugs. Labetalol was somewhat more effective in lowering upright blood pressure while atenolol caused a more pronounced heart-rate reduction. Both agents decreased plasma renin activity and urinary aldosterone excretion. Scalp tingling on labetalol (2 patients) and cold fingers with atenolol (1 patient) caused withdrawal of the drugs. Cold fingers were reported in another four patients during treatment with atenolol and in one when on labetalol. Tiredness and postural symptoms were more common during intake of labetalol.

A comparison of 100 mg atenolol and 100 mg metoprolol once a day at rest and during exercise in hypertensives

The effects of once daily dosage of the two cardioselective beta-adrenoceptor blocking agents, atenolol and metoprolol, were studied in 26 patients with primary hypertension. The study was a randomized double-blind cross-over trial with placebo run-in and wash-out. Assessment of effect was performed about 1 and 25 hours after dosing. At rest, both atenolol and metoprolol lowered the blood pressure (BP) and heart rate (HR) compared to placebo. Atenolol induced a more effective BP reduction than metoprolol, especially 25 hours after drug intake. During exercise 1 hour after dosing both drugs reduced BP and HR to a similar extent, whereas 25 hours after dosing atenolol gave a more efficient BP and HR reduction than metoprolol. Our data show that both 100 mg atenolol and 100 mg metoprolol are effective antihypertensive beta-blockers at rest and during exercise, 1 hour after intake. Metoprolol was less effective than atenolol 25 hours after dosing probably due to its shorter plasma half-life, thus implying a twice daily regimen for metoprolol in standard preparation.

Non-selective and selective beta-1-adrenoceptor blocking agents in the treatment of hyperthyroidism

Treatment for one month with propranolol or atenolol, a selective beta-1-adrenoceptor blocking agent, was evaluated in 20 hyperthyroid patients. The patients improved to the same extent on either drug, as shown by a clinical diagnostic index. Basal metabolic rate decreased by 11% during both treatments, while it was unchanged in seven untreated hyperthyroid controls. Thyroxine concentration did not change during any treatment. During propranolol treatment T3 decreased from 4.6 to 3.9 nmol/l, while no changes were observed during atenolol treatment or in the control group. No significant changes were seen in free T4, free T3 or rT3 concentrations on any treatment, although free T3 was observed to decrease slightly during propranolol treatment. Thus, the improvement of the clinical symptoms of hyperthyroidism cannot be explained by diminished thyroid hormone concentrations in serum, since the reduction was small during propranolol and absent during atenolol treatment.

Long-term effects of captopril and atenolol in essential hypertension

Fifty patients with mild or moderate essential hypertension were randomized (double-blindly) to treatment with either captopril (n = 26) or atenolol (n = 24). Their mean supine diastolic blood pressure after placebo was 100-125 mmHg. The study included an initial dose finding phase (12 weeks) during which the dosages of captopril and atenolol were increased stepwise every second week in order to obtain normotension (supine diastolic blood pressure less than 95 mmHg). Hydrochlorothiazide was added when necessary. During the second phase of the study the patients were followed on active treatment for 2 years. After the initial 12 weeks of active treatment, recumbent and standing blood pressures had fallen significantly both in the captopril group (by 31/20 and 33/19 mmHg, p less than 0.001) and in the atenolol group (by 24/18 and 30/20 mmHg, p less than 0.01 (systolic), p less than 0.001 (diastolic)). The antihypertensive effect was maintained in both groups during long-term treatment. The antihypertensive effect of both agents was potentiated to the same extent by addition of hydrochlorothiazide. Side-effects were few and mild. It can be concluded that both captopril and atenolol are safe and effective antihypertensive drugs.

Captopril, an orally active converting enzyme inhibitor, in the treatment of primary hypertension. A controlled long-term study with reference to initial plasma renin activity

Captopril (SQ 14 225), an orally active inhibitor of angiotensin converting enzyme, was evaluated in the treatment of primary (essential) hypertension in a placebo-controlled long-term study. In 24 patients allocated to captopril treatment, mean supine BP fell from 174 +/- 18/110 +/- 7 to 151 +/- 22/96 +/- 12 mmHg. Ten patients achieved a supine diastolic BP of less than or equally 90 mmHg with a mean BP fall of 28/22 mmHg after 4 weeks' captopril dose titration (75-450 mg daily). In 14 patients, BP fell 19/9 mmHg. When hydrochlorothiazide (50-100 mg daily) was subsequently added, a total supine BP reduction of 51/20 mmHg was noted. In the placebo control group (n = 16), BP changed +1/-2 mmHg from 171/110 mmHg while addition of hydrochlorothiazide caused a mean supine BP fall of 19/10 mmHg. During long-term follow-up (mean 11.8 months), no resistance to therapy developed. A weak correlation, (p less than 0.05) was seen between pretreatment plasma renin activity and initial captopril-induced BP reduction. However, in patients with clearly defined low renin hypertension, the hypotensive effect of captopril was much less than in patients with higher renin values. Captopril induced a significant decrease in urinary aldosterone excretion, which was partially reversed by addition of hydrochlorothiazide. Observed side-effects were proteinuria (1 case), rash (2 cases) and taste disturbances (3 cases). During long-term follow-up, seven patients have dropped out, four due to side-effects and three because of non-compliance.

Value of thyroid follow-up registers

In this study from a county in southern Sweden 269 of 271 patients (99.3%) treated with radioiodine for hyperthyroidism over a two-year period were followed up five years later. The routine procedures at hospital clinics and primary health care centres were studied. A high number of toxic multinodular goitre (n = 113; 42.0%) and toxic adenoma (n = 76; 28.3%) emerged, 80 patients (29.7%) had toxic diffuse goitre (Graves's disease). During the five-year follow-up the cumulative incidence of hypothyroidism in the various goitre groups was 10.7%, 23.9%, and 57.5% respectively. Altogether 76 patients (28.3%) were diagnosed hypothyroid. Nine patients were lost to regular follow-up; elevated TSH and low or normal T4-concentrations were found in two of them. We propose a register system to enable detection of thyroid dysfunction after radioiodine treatment and other thyroid patients in primary health care.

Early post-operative growth hormone levels predict the result of transsphenoidal tumour removal in acromegaly

Serum human growth hormone (hGH) measurements were performed during transsphenoidal microsurgery for acromegaly and in the early period afterwards. There were 14 patients of which 2 were operated on twice. In 11 patients (2 patients at reoperation) the serum hGH concentration was normalized to less than 5 micrograms/l within 3 h after completion of surgery. On five occasions only partial restoration of the hGH values was obtained and additional treatment was given in 2 patients by successful re-operation. The early post-operative hGH concentrations were consistent with the clinical evaluation of the patients and the hGH concentrations during follow-up for an average of 27 months. We conclude that early post-operative serum hGH measurement is of value for evaluation of the efficiency of the tumour removal and the need for further treatment.

Captopril, aldosterone and urinary kallikrein in primary hypertension

The effects on blood pressure, the renin-angiotensin-aldosterone and the kallikrein-kinin systems were investigated in 32 patients with primary hypertension WHO stage I-II treated with captopril. Hydrochlorothiazide was added if needed to achieve a supine diastolic blood pressure of less than or equal to 90 mmHg. A placebo control group (n=8) was treated similarly. Supine mean arterial pressure fell from 133 +/- 10 on placebo to 114 +/- 12 mmHg after 4 weeks on captopril. At the same time plasma aldosterone decreased from 263 +/- 188 to 164 +/- 101 pmol . 1(-1), 24 h urinary excretion of aldosterone from 18 +/- 12 to 12 +/- 10 nmol and kallikrein from 9.0 +/- 6.7 to 6.2 +/- 4.1 nkat. Plasma angiotensin II was significantly reduced after two weeks treatment from 23.2 +/- 8.6 to 17.0 +/- 6.7 pmol . 1(-1). Before, but not during captopril, 24 h urinary kallikrein excretion correlated with plasma aldosterone levels and 24 h urinary aldosterone excretion (r=0.44 p, less than 0.05 and r=0.53, p less than 0.01, respectively). Mean arterial pressure reduction on captopril correlated with pretreatment PRA (r=0.44, p less than 0.05) but not with other measured hormone levels or changes therein. The addition of hydrochlorothiazide caused a further fall in blood pressure, but increased plasma aldosterone and 24 h urinary kallikrein excretion. Hydrochlorothiazide alone increased only 24 h urinary aldosterone excretion significantly. These findings indicate that, besides aldosterone secretion and renal arterial pressure, further mechanisms regulating the release of and activity of the renal kallikrein-kinin system exist.

beta-Adrenoceptor-adenosine 3',5-monophosphate system in human leucocytes before and after treatment for hyperthyroidism

Modifications in characteristics of the beta-adrenoceptor-cAMP system were observed in leucocytes from 10 patients in the hyperthyroid state after antithyroid treatment. These include 1) an increased number of beta-adrenoceptors without a change in their affinity, 2) an increased magnitude of stimulation of adenylate cyclase by isoprenaline, without a change in the NaF-stimulated enzyme activity, 3) an increased cAMP-dependent protein kinase activity ratio, and 4) an increased activity of cAMP-phosphodiesterase. Moreover, the plasma cAMP levels were markedly elevated during the hyperthyroid state. It is suggested that the above changes may in part constitute the molecular basis for the reputed catecholamine supersensitivity in the hyperthyroid state.

Influence of hyperthyroidism on the kinetics of methimazole, propranolol, metoprolol and atenolol

The kinetic profiles of oral methimazole 40 mg, propranolol 80 mg, metoprolol 100 mg and atenolol 100 mg were compared in hyperthyroid patients both during the hyper- and euthyroid states. for methimazole, neither the peak concentration (Cmax), the time to reach peak concentration (tmax), the elimination half-life (t 1/2) nor the area under the curve (AUC) value was affected by the hyperthyroid state. For propranolol and metoprolol, which undergo extensive presystemic clearance, the AUC values were lower (p less than 0.02) when the patients were hyperthyroid than when they had become euthyroid, but the t 1/2's were not significantly altered. For atenolol, there were no significant kinetic differences between the hyperthyroid and euthyroid states. The findings are compatible with the assumption that hyperthyroidism does not affect the kinetics of methimazole or atenolol, but that it may enhance presystemic clearance of propranolol and metoprolol.

Long-term experience of captopril in the treatment of primary (essential) hypertension

1 Forty-one patients with primary (essential) hypertension were treated with captopril alone or in combination with hydrochlorothiazide for 12-36 months. 2 During an initial dose-titration period mean blood pressure fell from 174/111 mm Hg to 134/88 mm Hg supine and from 170/116 mm Hg to 126/93 mm Hg standing after 3 months' treatment. 3 During long-term treatment with unchanged or reduced doses of captopril or hydrochlorothiazide, or both, blood pressure remained substantially reduced. Mean supine blood pressure at 24 months was 136/90 mm Hg and at 36 months 138/90 mm Hg. 4 In 12 patients with clearly defined low renin (essential) hypertension initial blood pressure reduction was less than in patients with normal renin hypertension after 1 month's treatment (162/102 mm Hg v 143/92 mm Hg). After 24 months of treatment, however, the treatment results were similar in the two groups. 5 Except for one case of reversible proteinuria no serious side effects were seen during treatment periods of up to three years. 6 Captopril alone or in combination with hydrochlorothiazide seems to be an effective and safe drug in the long-term treatment of primary hypertension.

Radioimmunoassay of extracted glucagon compared with three non-extraction assays

Radioimmunoassay of glucagon was performed with three different antisera, i.e. E7, 30K and 4305, all directed against the carboxyl-terminal region of glucagon and thus avoiding co-determination of glucagon-like polypeptides from the gut. Plasma samples from five healthy people subjected to various A-cell stimulation and suppression tests were used and immunoreactive glucagon assessed with the three antisera. Aliquots from all plasma samples were also extracted with acetone and glucagon re-assessed with antiserum E7. Even though all four baseline glucagon concentrations obtained were different, the glucagon profiles were comparable after superimposing the baselines. The differences in baseline concentrations of immunoreactive glucagon seem due to the interference of "big plasma glucagon", a still unidentified factor in the E7 and 30K assays that can be precipitated by acetone. Since acetone extraction yielded the lowest baselines without altering the glucagon profiles, it is suggested that the baseline glucagon concentrations of acetone-extracted plasma reflect the physiological level of the biologically active hormone. Using antiserum E7, our own antiserum, the normal range of glucagon values in acetone-extracted plasma samples from 22 healthy, fasting people of both sexes was 42 +/- 16 ng/l (mean +/- 2 S.D.). These values agree well with those obtained by other assay techniques.

Timolol and hydrochlorothiazide-amiloride in primary hypertension

Fifty-five patients with primary hypertension, World Health Organization (WHO) stages I and II, were randomly allocated to a 9-mo multicenter, controlled, double-blind, crossover study with timolol, a nonselective beta adrenoceptor blocker, and hydrochlorothiazide combined with the potassium-sparing drug amiloride (AHCT). In 54% of the patients the blood pressure responded to timolol, in 87% to AHCT, and in 91% to a combination of the two. The diurectic was more effective than the beta blocker in patients with low-renin hypertension, who all responded to AHCT. Overall, there was no correlation between pretreatment plasma renin activity (PRA) and hypothensive effect of either drug. Timolol reduced PRA by 58% and plasma aldosterone (PA) by 23% while AHCT increased these levels threefold. Combination therapy increased PA while PRA returned towards baseline, suggesting greater aldosterone stimulation by the diuretic component. Serum triglycerides rose during timolol treatment alone and in combination. Both timolol and AHCT are effective antihypertensives. In combination they normalize blood pressure in most patients with primary hypertension (WHO stages I and II). Determination of PRA is useful as a guide to the choice of the first treatment in searching out low-renin hypertensive patients, who are best treated with diuretics.

Effects and plasma levels of propranolol and metoprolol in hyperthyroid patients

The effects and plasma concentrations of different doses of propranolol and metoprolol were studied in 34 hyperthyroid patients. The initial daily doses were propranolol 160 mg or metoprolol 200 mg. If the resting heart rate remained above 75 beats per min after treatment for 4-7 days, the dose was increased and the patient re-examined after a further 4-7 days. Propranolol (n = 17) caused a reduced heart rate, a decrease in serum 3,3',5-triiodothyronine (T3) and an increase in serum 3,3',5'-triiodothyronine (reverse T3, rT3). In 10 patients, there was no change in T3 or rT3 until the daily dose of propranolol had been increased to 240 or 320 mg. The plasma level of propranolol was significantly correlated with the decrease in T3 and the increase in rT3. Metoprolol (n = 17) caused a reduction in heart rate similar to that following propranolol. However, serum T3 was only slightly reduced even after an increase in dose to 300 or 400 mg, and serum rT3 was not altered. Metoprolol concentrations were not significantly correlated with the fall in T3. It appears that the influence of beta-blockers on T4 conversion is of little importance for the clinical improvement in hyperthyroid patients, and rather it is a consequence of beta 1-adrenergic blockade interfering with the effect of T3. In addition, the findings support the assumption that therapeutic failure with beta-blockers in hyperthyroidism may be due to suboptimal treatment, and that individualized dosage is necessary.

Cortisol, growth hormone and prolactin responses to insulin-induced hypoglycaemia in hyperthyroid patients before and during beta-adrenoceptor blockade

Two beta-adrenoceptor blocking agents, metoprolol (beta-1-selective) and propranolol (non-selective), were used in the treatment of hyperthyroid patients. The response of pituitary stress hormones to insulin-induced hypoglycaemia was investigated before and during beta-adrenoceptor blockage. Treatment with metoprolol (n=10) or propranolol (n=10) produced no changes in the cortisol or prolactin responses to hypoglycaemia. Moreover the growth hormone response remained unaltered during treatment with metoprolol. A small, but statistically significant, augmentation of growth hormone response was obtained during treatment with propranolol. When twelve subjects, euthyroid after final conventional treatment (surger), radioiodine or thyrostatic drugs), were re-examined, the cortisol and prolactin responses were unchanged, although growth hormone concentrations reached a slightly higher maximum value (P less than 0.01). It was concluded that treatment with beta-blocking agents in hyperthyroid subjects has no clinically important influence on the release of pituitary stress hormones during hypoglycaemia.

Effects of propranolol and atenolol on plasma and urinary cyclic adenosine 3',5'-monophosphate in hyperthyroid patients

Supine and upright plasma concentrations and the urinary excretion of cyclic adenosine 3′,5′-monophosphate (cAMP) were studied in 26hyperthyr oid patients before and during treatment for 3–6 days and one month with a non-selective (propranolol, n = 13) or a selective β-l-adrenergic antagonist (atenolol, n = 13). Before treatment supine and upright plasma concentrations of cAMP were elevated compared to healthy controls and compared to a re-investigation in the euthyroid state. Propranolol and atenolol both reduced supine and upright plasma cAMP and the reduction persisted during one month of treatment. In five untreated hyperthyroid patients no changes in plasma cAMP were observed between two different investigations. Turning to an upright posture was associated with an increase in plasma cAMP levels in 22 out of the 31 hyperthyroid patients (P < 0.05), while all 11 patients re-examined in the euthyroid state showed a rise in plasma cAMP in the upright position (P < 0.001). The 24 h urinary excretion of cAMP was unaltered during treatment with β-adrenergic antagonists.

The data support earlier findings of stimulation of adrenergic receptor activity by thyroid hormone excess. In hyperthyroidism β-adrenergic antagonists decrease but do not normalize the activity of the adenylate cyclase system. This reducing effect may be of importance for the alleviation of hyperthyroid symptoms and signs during treatment with β-adrenergic antagonists.

Insulin release and carbohydrate tolerance in hyperthyroid patients during non-selective or selective beta-1-adrenoceptor blockade

The insulin release and the glucose disappearance rate (K-value) during an iv glucose tolerance test were evaluated in 20 hyperthyroid patients before and during treatment with either a non-selective (propranolol, n = 10) or a selective (metoprolol, n = 10) beta-1-adrenoceptor blocking agent. Mean daily doses were 240 mg of propranolol and 280 mg of metoprolol, administered four times daily for 10 to 14 days. The insulin increase after glucose injection remained unchanged during treatment with each drug. Fasting blood glucose concentrations and the K-values were not altered during treatment. Sixteen patients were re-investigated 10 to 36 weeks later when euthyroid due to treatment by surgery, thyrostatic drugs or radioiodine. In the euthyroid state mean serum insulin concentrations after the glucose load were not significantly different from the values found when the patients were hyperthyroid. However, mean fasting blood glucose concentrations decreased from 5.5 mmol/l to 5.0 (P less than 0.01) and the mean K-value increased from 1.5 to 2.0 (P less than 0.05) when the patients were euthyroid. It is concluded that short-term treatment of hyperthyroid patients with non-selective or selective beta-1-adrenoceptor blocking agents does not impair the glucose stimulated insulin secretion or the carbohydrate tolerance.