. 2021 Dec 14;9(12):1899. doi: 10.3390/biomedicines9121899

Table 1.

Characteristics of included studies investigating nitrite and/or nitrate levels in multiple sclerosis patients (MS) versus patients with noninflammatory other neurological diseases (NIOND). CSF = cerebrospinal fluid, NOx = sum of nitrite and nitrate, C = concentration in µM, SD = standard deviation, SEM = standard error of mean, IQR = interquartile range, n/a = data not given or not applicable, GC–MS = gas chromatography–mass spectrometry, DAN = diaminonaphthalene, ^a = median (range), ^b = mean (SEM), ^c = median (IQR).

Study	Year	Specimen	MS Patients					NIOND Patients					Assay
Study	Year	Specimen	N (m/f)	Mean Age in Yrs (±SD)	C Mean (Nitrite) (±SD)	C Mean (Nitrate) (±SD)	C Mean (NOx) (±SD)	N (m/f)	Mean Age in Yrs (±SD)	C Mean (Nitrite) (±SD)	C Mean (Nitrate) (±SD)	C Mean (NOx) (±SD)	Assay
Cross et al. [19]	1998	CSF	13 (n/a)	n/a	9.98 (34.6)	47.8 (150)	n/a	43 (n/a)	n/a	0.64 (1.21)	3.01 (2.13)	n/a	Fluorometric assay (DAN)
Haghikia et al. [20]	2015	CSF	14 (6/8)	45 (9.6)	2.84 (0.32)	11.3 (0.56)	n/a	26 (12/14)	56.27 (15.8)	2.41 (0.11)	10.5 (0.32)	n/a	GC/MS
Ikeda et al. [21]	1995	CSF	13 (n/a)	34.6 (4.1)	0.62 (0.07)	8.3 (0.6)	n/a	29 (n/a)	54.0 (3.8)	0.63 (0.04)	7.6 (0.7)	n/a	Spectrophotometric assay (Griess)
de Bustos et al. [22]	1999	CSF	11 (5/6)	36.0 (11.3)	n/a	6.2 (2.3)	n/a	25 (10/15)	35.4 (10.7)	n/a	6.9 (3.1)	n/a	Semiautomated assay (Griess)
de Bustos et al. [22]	1999	serum	11 (5/6)	36.0 (11.3)	n/a	22.7 (6.4)	n/a	25 (10/15)	35.4 (10.7)	n/a	37.1 (23.9)	n/a	Semiautomated assay (Griess)
Seven et al. [23]	2013	CSF	20 (7/13)	31.0 (9.6)	n/a	n/a	86.28 (34.1)	15 (6/9)	28.33 (5.31)	n/a	n/a	52.52 (16.5)	Fluorometric assay (Sulphanilamide)
Drulovic et al. [24]	2001	CSF	57 (n/a)	n/a	n/a	n/a	9.5 (1.7)	27 (n/a)	n/a	n/a	n/a	8.7 (2.8)	Spectrophotometric assay (Griess)
Brundin et al. [25]	1999	CSF	9 (n/a)	43.1 (15.0)	9.3 (2.8) ^b	9.5 (1.7) ^b	15.1 (3.1) ^b	8 (2/6)	45.0 (17.0)	2.3 (0.5) ^b	5.2 (0.5) ^b	7.5 (0.5) ^b	Capillary electrophoresis
Johnson et al. [26]	1995	CSF	10 (n/a)	n/a	n/a	n/a	2.59 (0.32) ^b	10 (n/a)	n/a	n/a	n/a	1.53 (0.22) ^b	Spectrophotometric assay (Griess)
Yuceyar et al. [27]	2001	CSF	15 (2/13)	29.93 (n/a)	4.85 (3.35)	19.64 (5.59)	24.54 (6.23)	15 (5/10)	43.2 (19.7)	2.61 (1.77)	13.72 (5.17)	16.34 (5.74)	Spectrophotometric assay (Griess)
Yuceyar et al. [27]	2001	serum	15 (2/13)	29.93 (n/a)	5.84 (2.86)	35.98 (35.04)	41.83 (36.41)	15 (5/10)	43.2 (19.7)	2.89 (3.31)	19.75 (6.62)	22.65 (7.8)	Spectrophotometric assay (Griess)
Rejdak et al. [28]	2004	CSF	20 (n/a)	n/a	n/a	n/a	11.3 (4.9)	14 (6/8)	45 (23–74) ^a	n/a	n/a	6.3 (2.3)	Spectrophotometric assay (Griess)
Rejdak et al. [28]	2004	serum	20 (n/a)	n/a	n/a	n/a	43.8 (8.3)	14 (6/8)	45 (23–74) ^a	n/a	n/a	36.0 (15.9)	Spectrophotometric assay (Griess)
Rejdak et al. [29]	2008	CSF	34 (9/25)	31.0 (20–52) ^a	n/a	n/a	8.5 (2.5–21.5) ^a	12 (3/9)	29 (22–50) ^a	n/a	n/a	2.5 (0.9–7.1) ^a	Spectrophotometric assay (Griess)
Pirrtilä et al. [30]	2004	CSF	8 (1/7)	28.9 (8.9)	n/a	n/a	1.22 (0.17)	25 (7/18)	47.5 (12.9)	n/a	n/a	1.47 (0.82)	Spectrophotometric assay (Griess)
Danilov et al. [31]	2003	CSF	24 (6/18)	43.5 (19–60) ^a	7.7 (1.1) ^b	9.6 (0.7) ^b	17.3 (1.6) ^b	8 (2/6)	44.7 (26–66) ^a	n/a	5.4 (0.3) ^b	7.4 (0.5) ^b	Capillary electrophoresis
Miljkovic et al. [32]	2002	CSF	50 (13/37)	35.1 (10.6)	n/a	n/a	9.48 (1.98)	23 (n/a)	n/a	n/a	n/a	8.49 (1.33)	Spectrophotometric assay (Griess)
Giovannoni et al. [33]	1997	serum	21 (5/16)	40.6 (10.7)	n/a	n/a	74.3 (33.7)	14 (7/7)	47.8 (17.8)	n/a	n/a	41.1 (12.3)	Spectrophotometric assay (Griess)
Calabrese et al. [34]	2002	CSF	15 (3/12)	31.0 (7.3)	n/a	n/a	9.4 (1.1) ^b	15 (2/13)	32.4 (11.0)	n/a	n/a	5.2 (0.9) ^b	Spectrophotometric assay (Griess)
Sellebjerg et al. [35]	2002	CSF	35 (5/30)	38 (32.0–43.0) ^c	n/a	n/a	5.5 (3.6–9.1) ^c	15 (4/11)	45 (45.0–60.0) ^c	n/a	n/a	3.3 (1.4–4.9) ^c	Spectrophotometric assay (Griess)
Sellebjerg et al. [35]	2002	serum	35 (5/30)	38 (32.0–43.0) ^c	n/a	n/a	34.3 (27.0–47.3) ^c	15 (4/11)	45 (45.0–60.0) ^c	n/a	n/a	40.7 (36.5–51.1) ^c	Spectrophotometric assay (Griess)