The role of older age and obesity in minimally invasive and open pancreatic surgery: A systematic review and meta-analysis

BACKGROUND/OBJECTIVES

The aim of this study was to assess the impact of older age (≥70 years) and obesity (BMI ≥30) on surgical outcomes of minimally invasive pancreatic resections (MIPR). Subsequently, open pancreatic resections or MIPR were compared for elderly and/or obese patients.

METHODS

A systematic review was conducted as part of the 2019 Miami International Evidence-Based Guidelines on MIPR (IG-MIPR). Study quality assessment was according to The Scottish Intercollegiate Guidelines Network (SIGN). A meta-analysis was performed to assess the impact of MIPR or open pancreatic resections in elderly patients.

RESULTS

After screening 682 studies, 13 observational studies with 4629 patients were included. Elderly patients undergoing laparoscopic distal pancreatectomy (LDP) had less blood loss (117 mL, p < 0.001) and a shorter hospital stay (3.5 days p < 0.001) than elderly patients undergoing open distal pancreatectomy (ODP). Postoperative pancreatic fistula (POPF) B/C, major complication and reoperation rate were not significantly different in elderly patients undergoing either laparoscopic or open pancreatoduodenectomy (OPD). One study compared robot PD with OPD in obese patients, indicating that patients with robotic surgery had less blood loss (mean 250 ml vs 500 ml, p = 0.001), shorter operative time (mean 381 min vs 428 min, p = 0.003), and lower rate of POPF B/C (13% vs 28%, p = 0.039).

CONCLUSION

The current available limited evidence does not suggest that MIPR is contraindicated in elderly or obese patients. Additionally, outcomes in MIPR are equal or more beneficial compared to the open approach when applied in these patient groups.

Analysis of the Eurotransplant Kidney Allocation Algorithm: How Should We Balance Utility and Equity?

BACKGROUND

Since 2014, expected graft and recipient survival are matched by the U.S. kidney allocation system to improve organ utility. This mechanism is based on the kidney donor profile index (KDPI) and the estimated posttransplant survival score (EPTS). Here we analyzed 1. the transferability of these scores into the Eurotransplant (ET) region and 2. the extent to which the ET kidney allocation algorithm promotes utility.

METHODS

We studied data of 262 kidney transplantations performed at the University Hospital Kiel between 2000 and 2009 (median follow-up, 9.94 years).

RESULTS

Multivariable Cox regression analysis revealed that only the variables donor age of the KDPI and recipient's age of the EPTS have a significant value as predictors of posttransplant graft and recipient survival. The other variables showed no additional predictive value. Analyzing all kidneys allocated in the ET kidney allocation system and the European Senior Program, we found that donor and recipient's age and KDPI and EPTS were weakly correlated (r_age-age = 0.5, P < .001; r_KDPI-EPTS = 0.4, P < .01). If both programs were analyzed separately, no correlation between donor and recipient's age and between KDPI and EPTS was detected.

CONCLUSION

The ET kidney allocation algorithm poorly matched predicted graft and recipient survival at our center. A better age-matching may improve organ utility.

Hypothermia improves oral and gastric mucosal oxygenation during hypoxic challenges

BACKGROUND

Therapeutic hypothermia, used primarily for protective effects after hypoxia, improves oral and gastric mucosal microvascular oxygenation (μHbO₂) during additional haemorrhage. Therefore, we questioned whether hypothermia likewise improves μHbO₂ during hypoxic challenges. Since both hypothermia and hypoxia reduce cardiac output (e.g. by myofilament Ca(2+) desensitization), and modulate vasomotor tone via K(+) ATP channels, we hypothesized that the Ca(2+) sensitizer levosimendan and K(+) ATP channel blocker glibenclamide would support the cardiovascular system.

METHODS

The effects of mild hypothermia (34°C) on μHbO₂ during hypoxia [Formula: see text] were analysed in a cross-over study on five anaesthetized dogs and compared with normothermia (37.5°C) and hypoxia. During hypothermia, but before hypoxia, glibenclamide (0.2 mg kg(-1)) or levosimendan (20 µg kg(-1)+0.25 µg kg(-1) min(-1)) was administered. Systemic haemodynamic variables, gastric and oral mucosal microvascular oxygenation (reflectance spectrophotometry), and perfusion (laser Doppler flowmetry) were recorded continuously. Data are presented as mean (sem), P<0.05.

RESULTS

Hypoxia during normothermia reduced gastric μHbO₂ by 27 (3)% and oral μHbO₂ by 28 (3)% (absolute change). During hypothermia, this reduction was attenuated to 16 (3)% and 13 (1)% (absolute change). This effect was independent of microvascular flow that did not change during hypoxia and hypothermia. Additional administration of levosimendan during hypothermia restored reduced cardiac output but did not change flow or μHbO₂ compared with hypothermia alone. Glibenclamide did not exert any additional effects during hypothermia.

CONCLUSIONS

Hypothermia attenuates the decrease in μHbO₂ during additional hypoxic challenges independent of systemic or regional flow changes. A reduction in cardiac output during hypothermia is prevented by Ca(2+) sensitization with levosimendan but not by K(+) ATP channel blockade with glibenclamide.

Potential roles of ATP and local neurons in the monitoring of blood O2 content by rat aortic bodies

Aortic bodies are arterial chemoreceptors presumed to monitor blood O2 content by unknown mechanisms, in contrast to their well-studied carotid body counterparts, which monitor PO2 and /pH. We recently showed that rat aortic body chemoreceptors (type I cells), located at the left vagus-recurrent laryngeal nerve bifurcation, responded to PO2 and PCO2 /pH in a manner similar to carotid body type I cells. These aortic bodies are uniquely associated with a group of local neurons, which are also sensitive to these stimuli. Here, we hypothesized that these local neurons may contribute to monitoring blood O2 content. During perforated patch recordings, ATP, known to be released from (carotid body) type I cells and red blood cells during hypoxia, induced inward currents and excited ≈ 45% of local neurons (EC50 ≈ 1 μm), mainly via heteromeric P2X2/3 purinoceptors. While ATP also induced a rise in intracellular [Ca(2+)] in a subpopulation of these neurons, almost all of them responded to nicotinic cholinergic agonists. During paired recordings, several juxtaposed neurons showed strong bidirectional electrical coupling, suggesting a local co-ordination of electrical activity. Perfusion with Evans Blue dye resulted in labelling of aortic body paraganglia, suggesting they have ready access to circulatory factors, e.g. ATP released from red blood cells during hypoxia. When combined with confocal immunofluorescence, the dye-labelled regions coincided with areas containing tyrosine hydroxylase-positive type I cell clusters and P2X2-positive nerve endings. We propose a working model whereby local neurons, red blood cells, ATP signalling and low blood flow contribute to the unique ability of the aortic body to monitor blood O2 content.

Complications of a buried penis in an extremely obese patient

The buried penis syndrome in adults is a rare condition of different aetiologies. Today extreme obesity is considered as a major contributor. We present a case of a 30-year-old extremely obese patient (BMI 65 kg/m(2)) with purulent infection of the penile cavity, a phlegmon of the mons pubis and urinary retention due to a buried penis. Whereas acute complications of a buried penis in obese patients include local infection and urinary retention, chronic problems are undirected voiding, disturbed vaginal penetration and erectile dysfunction. Even though several surgical techniques are described, weight reduction should be primarily preferred.

TEM foil preparation of sub-micrometre sized individual grains by focused ion beam technique

Analysis of presolar silicate grains provides new knowledge on interstellar and circumstellar environments and can be used to test models of the Galactic chemical evolution. However, structural information of these grains is rare because sample preparation for transmission electron microscopy is very difficult due to the small dimensions of these grains (<0.5 mum). With the use of the focused ion beam technique thin foils from these grains for transmission electron microscopy analysis can be prepared. Nevertheless, reaching the required precision of some tens of nanometres for the preparation of the transmission electron microscopy foil in the place of interest is not trivial. Furthermore, in the current samples, the grain of interest can only be identified by its different isotopic composition; i.e. there is no contrast difference in scanning electron microscopy or transmission electron microscopy images which allow the identification of the grain. Therefore, the grain has to be marked in some way before preparing the transmission electron microscopy foil. In the present paper, a method for transmission electron microscopy foil preparation of grains about 200 to 400 nm in diameter is presented. The method utilizes marking of the grain by Pt deposition and milling of holes to aid in the exact orientation of the transmission electron microscopy foil with respect to the grain. The proposed method will be explained in detail by using an example grain.

Expression of P2X2 and P2X3 receptor subunits in rat carotid body afferent neurones: role in chemosensory signalling

1. Hypoxic chemotransmission in the rat carotid body (CB) is mediated in part by ATP acting on suramin-sensitive P2X purinoceptors. Here, we use RT-PCR, cloning and sequencing techniques to show P2X2 and P2X3 receptor expression in petrosal neurones, some of which develop functional chemosensory units with CB receptor clusters in co-culture. 2. Single-cell RT-PCR revealed that hypoxia-responsive neurones, identified electrophysiologically in co-culture, expressed both P2X2 and P2X3 mRNA. 3. Isohydric hypercapnia (10 % CO(2); pH 7.4) caused excitation of chemosensory units in co-culture. This excitation depended on chemical transmission, with ATP acting as a co-transmitter, since it was inhibited by reduction of the extracellular Ca(2+):Mg(2+) ratio and by the purinoceptor blocker suramin (50-100 microM). 4. Hypoxia and isohydric hypercapnia could separately excite the same chemosensory unit, and together the two stimuli interacted synergistically. 5. Using confocal immunofluorescence, co-localization of P2X2 and P2X3 protein was demonstrated in many petrosal somas and CB afferent terminals in situ. Taken together, these data indicate that ATP and P2X2-P2X3 purinoceptors play important roles in the peripheral control of respiration by carotid body chemoreceptors.

Dimensional overlap between arrows as cueing stimuli and responses? Evidence from contra-ipsilateral differences in EEG potentials

In the S1-S2 interval, 400 ms after an arrow as S1, an EEG-potential difference occurs between scalp sites contralateral and ipsilateral to arrow direction. Eimer [J. Exp. Psychol. Hum. Percept. Perform. 21 (1995) 837-854] interpreted this difference as a sign of automatic activation of the manual response, due to dimensional overlap of arrows and responses. However, according to Kornblum et al.'s [Psychol. Rev. 97 (1990) 253-270] notion of dimensional overlap, responses can only be automatically primed if they are included in the response set. Therefore, participants of the present study had to respond to S2 in separate blocks either by key-press, as in Eimer [J. Exp. Psychol. Hum. Percept. Perform. 21 (1995) 837-854], or by making saccades. In addition, contra-ipsilateral differences were recorded not only from central positions, overlying the hand-motor area, but across the whole scalp. Contralateral negativity at 400 ms after S1 was indeed found over the hand-motor area in the 'hand blocks'. However, this 'L-400' (=lateralization at 400 ms) was generally as large in the 'eye' blocks as in the 'hand' blocks. Therefore, L-400 does not reflect automatic activation of manual responses in the sense of Kornblum et al. [Psychol. Rev. 97 (1990) 253-270]. Further, its topographical maximum was more anterior than the hand-motor-related negativity that preceded the manual response ('LRP') with its maximum at central sites. Therefore, L-400 probably does not originate in the hand-motor cortex. Rather, it may be related to activity of the lateral premotor cortex found in fMRI studies of spatial orienting. The present EEG study extends these studies by delimiting the time period of this activity, suggesting that it reflects encoding of the spatial properties of the arrow for action.

Co-release of ATP and ACh mediates hypoxic signalling at rat carotid body chemoreceptors

Using functional co-cultures of rat carotid body (CB) O2 chemoreceptors and 'juxtaposed' petrosal neurones (JPNs), we tested whether ATP and ACh acted as co-transmitters. Perforated-patch recordings from JPNs often revealed spontaneous and hypoxia-evoked (PO2 approximately 5 mmHg) excitatory postsynaptic responses. The P2X purinoceptor blocker, suramin (50 microM) or a nicotinic ACh receptor (nAChR) blocker (hexamethonium, 100 microM; mecamylamine, 1 microM) only partially inhibited these responses, but together, blocked almost all activity. Under voltage clamp (-60 mV), fast perfusion of 100 microM ATP over hypoxia-responsive JPNs induced suramin-sensitive (IC50 = 73 microM), slowly-desensitizing, inward currents (IATP) with time constant of activation tauon = 30.6 +/- 4. 8 ms (n = 7). IATP reversed at 0.33 +/- 3.7 mV (n = 4), and the dose-response curve was fitted by the Hill equation (EC50 = 2.7 microM; Hill coefficient approximately 0.9). These purinoceptors contained immunoreactive P2X2 subunits, but their activation by alpha,beta-methylene ATP (alpha,beta-meATP; EC50 = 2.1 microM) suggests they are P2X2/P2X3 heteromultimers. Suramin and nAChR blockers inhibited the extracellular chemosensory discharge in the intact rat carotid body-sinus nerve preparation in vitro. Further, P2X2 immunoreactivity was widespread in rat petrosal ganglia in situ, and co-localized in neurones expressing the CB chemo-afferent marker, tyrosine hydroxylase (TH). P2X2 labelling in the CB co-localized with nerve-terminal markers, and was intimately associated with TH-positive type 1 cells. Thus ATP and ACh are co-transmitters during chemotransduction in the rat carotid body.

Role of ET-1 in hypoxia-induced mitosis of cultured rat carotid body chemoreceptors

The mammalian carotid body (CB) contains O2-chemoreceptors, i.e. glomus cells, which display increased mitoses and endothelin-1 (ET-1) expression during chronic hypoxia. To investigate whether endogenous ET-1 might mediate these mitogenic effects, we quantified bromodeoxyuridine (BrdU) uptake by tyrosine hydroxylase (TH)-positive glomus cells in rat CB cultures using double-label immunofluorescence. In normoxia (20% O2), 2-day exposure to ET-1 (10-1000 nM) caused a dose-dependent increase in BrdU uptake which peaked (approximately 55% of TH+ cells) at around 500 nM ET-1. In chronic hypoxia (5% O2) alone, BrdU uptake was stimulated (approximately 46% of TH+ cells) relative to normoxia (approximately 30%), but the effect was abolished in the presence of specific (BQ 123) or non-specific (PD 142893) ETA receptor antagonists (10(-5) M). Thus paracrine/autocrine release of ET-1 in the hypoxic carotid body may promote glomus cell mitosis via ET(A) receptors.

Role of basic FGF and oxygen in control of proliferation, survival, and neuronal differentiation in carotid body chromaffin cells

Crest-derived glomus cells of the carotid body (CB) are O(2)-sensitive chemoreceptors, which resemble sympathoadrenal (SA) chromaffin cells. In this study, we tested whether perinatal rat glomus cells are sensitive to basic fibroblast growth factor (bFGF) in vitro and whether their sensitivity is regulated by oxygen. In chemically defined medium, bFGF (1-100 ng/ml) caused a significant, dose-dependent increase in the number of surviving tyrosine hydroxylase-positive (TH+) glomus cells in embryonic (E17-E19) CB cultures, following a 48-hr exposure. Though basic FGF (10 ng/ml) appeared mitogenic for these cells, based on stimulation of bromodeoxyuridine (BrdU) uptake, it supported survival of only approximately 60% of the initial TH+ population, suggesting that significant cell death was occurring. This apparent cell loss in E17 cultures could be largely prevented by combined treatment with bFGF and low oxygen (6% O(2)). In contrast, in early postnatal (P1) cultures, glomus cell number was relatively unchanged over 48 hr under control conditions or in presence of mitogenic activity from either bFGF or low oxygen. However, combined treatment with both bFGF and low oxygen stimulated proliferation of P1 glomus cells such that by 48 hr the TH+ population had increased to approximately 1.5x the initial density. Basic FGF (10 ng/ ml) also stimulated neurite outgrowth and neurofilament expression in E18-E19, but not P1-P3, glomus cells. In contrast to bFGF, treatment with nerve growth factor was ineffective. Taken together, these results suggest that bFGF and low oxygen are mitogens for perinatal CB chromaffin cells and interact cooperatively as survival factors. It is plausible that these mechanisms may operate to regulate chemoreceptor cell density, during the animal's transition from in utero (hypoxic) to ex utero (normoxic)life.

Immunocytochemical localization on O2-sensing protein (NADPH oxidase) in chemoreceptor cells

A potential candidate for an oxygen-sensing protein in chemoreceptor cells is a heme-linked multicomponent NADPH oxidase, originally described in neutrophils. The postulated function for the oxidase in chemoreceptor cells is to signal changes in oxygen levels (either in the blood or in the airway lumen) via changes in oxygen metabolite production. An alteration in either superoxide (or dismuted hydrogen peroxide) production may affect the gating properties of the O2-sensitive K+ channels. We have previously reported immunohistochemical localization of gp91 glycoprotein component of the oxidase to the plasma membrane of pulmonary neuroepithelial body (NEB) cells. In this study we have investigated the immunocytochemical localization of the other polypeptide components of the oxidase in NEB cells and in the glomus cells of the carotid body. Cultures of dissociated fetal rabbit NEB cells and newborn rat glomus cells were immunostained with specific antibodies recognizing the various polypeptide subunits of the oxidase using indirect immunofluorescence methods. Immunostaining with the anti-oxidase antibodies reveal strong positive reaction in both NEB and glomus cell clusters while other cells were unstained. The positive reaction product was localized to the plasma membrane and/or cytoplasm and no nuclear staining was observed. Live cell labelling studies with anti-p22 antibody showed positive immunofluorescence on the surface of NEB cells, suggesting that this component of the oxidase is also associated with the plasma membrane. In glomus cells, similar strongly positive immunofluorescence signal was observed for p22 and gp91 in paraformaldehyde-fixed cultures, regardless whether they were permeabilized or not. Taken together, our findings of cell surface localization of gp91 and p22 components of the oxidase in chemoreceptive cells suggests that the heme-linked cytochrome b558 component is associated with the plasma membrane. This association allows for direct interaction with the O2-sensitive K+ channel thus forming the molecular complex of membrane bound O2 sensor.

Intratumoral rIL2-based immunotherapy in B16 melanoma

Limiting factors in systemic recombinant interleukin-2 (rIL2) therapy may be overcome by intratumoral (IT) administration. A series of experiments was conducted to assess the efficacy of IT rIL2 alone and in combination with LAK cells and IFN-gamma. C57BL/6 mice bearing B16-F10 subcutaneous tumors were randomly assigned to treatment groups including: noninjected controls, IT placebo (NaCl, D5W), IT bovine serum albumin (BSA), IT rIL2 (centrally and peripherally), IT rIL2/LAK, IT rIL2/IFN-gamma, and intraperitoneal (IP) rIL2. A tumor size-dependent dose of cytokine was injected daily and LAK cells were given weekly. Systemic immune response was assessed by splenocyte mitogenesis and T-cell subset distribution using thymidine radioassay and flow cytometry, respectively. In terms of survival and tumor growth rate, IT rIL2 was superior to noninjected control, IT placebo, IT BSA, and IP rIL2 (P less than 0.05). The addition of IT LAK cells conferred no therapeutic advantage. The combination of rIL2 and gamma IFN-gamma had a slight survival benefit over rIL2 alone (30.8 days vs 20.4 days). Histologic analysis demonstrated an increase presence of intratumoral macrophages in the IT rIL2-treated tumors (P less than 0.05). Lymphocyte mitogenesis and L3T4+ subset were not altered by any treatment. In vitro thymidine uptake by tumor cells was not affected by rIL2 nor IFN-gamma alone but the combination of rIL2 and IFN-gamma resulted in significant tumor cell growth inhibition. Spontaneous lung metastases were more prevalent following central IT rIL2 (75% vs 29%, P = 0.07) not accountable by needle trauma but avoidable by the use of peritumoral injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular hypertrophy reversal with labetalol and propranolol: a prospective randomized, double-blind study

Hypertensive patients with left ventricular hypertrophy (LVH) have increased cardiovascular morbidity and mortality. Experimental studies indicate the importance of both the alpha and beta components of the adrenergic nervous system in the development and reversal of LVH. Therefore labetalol (L), a combined alpha and beta blocker, and propranolol (P), a nonselective beta blocker, were evaluated in a randomized, double-blind study of 35 hypertensive patients with echocardiographic evidence of LVH. Following 2 weeks of placebo, L or P was titrated as needed and tolerated to maximum total daily doses of 1600 mg and 640 mg, respectively. A thiazide diuretic was added if necessary for blood pressure control. M-mode echocardiograms were performed at baseline and after 1, 3, 6, and 12 months of blood pressure control. The echocardiograms were read independently by two blinded observers for end-diastolic dimension and wall thicknesses, and left ventricular mass. Fractional shortening, cardiac output, and peripheral vascular resistance were derived using standard formulas. Both drugs reduced blood pressure significantly and comparably. Significant changes in the echocardiographic measurements were observed as early as 1 month and usually persisted throughout the study. Both drugs decreased posterior wall thickness; however, only the decrease in propranolol group achieved statistical significance. Septal wall thickness was reduced by L at 3 and 12 months. End-diastolic dimension increased significantly in the L-treated group at 3, 6, and 12 months of therapy, whereas P had no effect on this measurement.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of diltiazem on left ventricular mass and diastolic filling in mild to moderate hypertension

It is still uncertain whether antihypertensive therapy with calcium antagonists in general, and diltiazem in particular, can reduce left ventricular (LV) mass index and improve LV diastolic filling in hypertension. Therefore, 24 patients with mild to moderate hypertension (diastolic blood pressure 95 to 114 mm Hg before therapy) were randomly assigned to receive either a sustained-release preparation of diltiazem (n = 13) or placebo (n = 11) for 16 weeks in a double-blind, parallel-group protocol. M-mode and pulsed Doppler echocardiograms were performed at baseline and at the end of monotherapy. Echocardiograms were read blindly by 2 independent observers. The patients who received placebo exhibited no change in blood pressure, cardiac dimensions or LV function. Diltiazem significantly reduced both systolic pressure (151 +/- 14 to 139 +/- 12 mm Hg) and diastolic pressure (101 +/- 4 to 90 +/- 7 mm Hg, both p less than 0.05). Posterior wall and septal wall thicknesses decreased, but the changes were not statistically significant. End-diastolic dimension was reduced by diltiazem from 53 +/- 5 to 51 +/- 5 mm (p less than 0.05). LV mass index decreased significantly with diltiazem by 10%, from 125 +/- 21 to 113 +/- 23 g/m2 (p less than 0.05). The LV wall thickness to radius ratio remained unchanged during both diltiazem and placebo treatments. Changes in LV mass index and blood pressure did not correlate, suggesting that this response is influenced by factors other than pressure reduction alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Diltiazem versus propranolol in essential hypertension: responses of rest and exercise blood pressure and effects on exercise capacity

Both beta-blocking and calcium channel-blocking drugs are being used with increasing frequency as initial therapy for essential hypertension. The present study was designed to compare the antihypertensive effects of a beta-blocking drug, propranolol, with a calcium channel-blocking drug, diltiazem, at rest and during upright bicycle exercise and to determine whether exercise capacity is altered by these therapies. Twenty-one patients with uncomplicated systemic hypertension and a diastolic blood pressure (BP) of 95 to 110 mm Hg without medication were randomly assigned to propranolol or diltiazem therapy in a double-blind manner. The total daily dosages were titrated as needed, from 160 to 480 mg of propranolol (mean 371 mg) and 120 to 360 mg of diltiazem (mean 307 mg) over 12 weeks, and the titrated dose was maintained for 4 additional weeks. Both drugs significantly reduced supine BP (from 149 +/- 14/101 +/- 4 to 136 +/- 17/89 +/- 10 mm Hg with propranolol and from 157 +/- 14/103 +/- 4 to 144 +/- 13/93 +/- 8 with diltiazem. Only diltiazem reduced BP during submaximal exercise, but both agents produced significant responses during maximal exercise. Diltiazem had no effect on maximal heart rate, exercise duration or O2 uptake, whereas propranolol reduced maximal VO2 from 27 +/- 6 to 22 +/- 6 ml/min/kg (p less than 0.01) and also shortened duration of exercise. Propranolol, despite its effects on heart rate, maintained the workload VO2 relation at submaximal loads, suggesting an increased oxygen delivery. However, these adaptive mechanisms appear to be insufficient during maximal effort.

Comparison and additivity of nitrendipine and hydrochlorothiazide in systemic hypertension

Calcium channel blockers are highly effective antihypertensive agents and provide a good alternative to other medications used as initial or monotherapy. Although the calcium channel blockers act as peripheral vasodilators, they are unique among this group of drugs in lowering blood pressure in a sustained manner; several compensatory mechanisms are inhibited by virtue of either direct or indirect effects of these agents. In recent years, hypertension has generally been treated with a step-care approach, the limitations of which are now becoming apparent. Today, 4 classes of agents are effective and well tolerated as single therapy and might therefore be considered as first-line drug therapy: diuretics, beta blockers, converting enzyme inhibitors and calcium channel blockers. Preliminary results from an ongoing double-blind randomized trial comparing nitrendipine (a calcium channel blocker) and hydrochlorothiazide (a diuretic) in mild to moderate hypertension will be presented. Results from 63 patients showed the 2 agents to be equivalent in antihypertensive effects and in frequency of adverse reactions. Other data indicate that when nitrendipine and hydrochlorothiazide were combined, a further decrease in blood pressure was observed. Patient characteristics affecting drug choice and clinical situations in which calcium channel blockers can be used most effectively can now often be delineated.