Acts 1:15 Καὶ ἐν ταῖς ἡμέραις ταύταις ἀναστὰς Πέτρος ἐν μέσῳ τῶν ἀδελφῶν εἶπεν· ἦν τε ὄχλος ὀνομάτων ἐπὶ τὸ αὐτὸ ὡσεὶ ἑκατὸν εἴκοσι· 16 ἄνδρες ἀδελφοί, ἔδει πληρωθῆναι τὴν γραφὴν ἣν προεῖπεν τὸ πνεῦμα τὸ ἅγιον διὰ στόματος Δαυὶδ περὶ Ἰούδα τοῦ γενομένου ὁδηγοῦ τοῖς συλλαβοῦσιν Ἰησοῦν
Acts 1:15 In those days Peter stood up among the brethren [and] said (the company of persons was in all about a hundred and twenty), 16 “Brethren, the scripture had to be fulfilled ...
Acts 2:37 Ἀκούσαντες δὲ κατενύγησαν τὴν καρδίαν εἶπόν τε πρὸς τὸν Πέτρον καὶ τοὺς λοιποὺς ἀποστόλους· τί ποιήσωμεν, ἄνδρες ἀδελφοί;
Acts 2:37 Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, “Brethren, what shall we do?”
It seems to me that there is a difference between these two examples. The second example where the addressees are specified in a parenthetical expression between the verb of speaking εἶπόν and the direct speech (italics) is pretty standard fare. τε πρὸς τὸν Πέτρον ... encodes syntactically the addressee relationship to the verb of speech. The function of the parenthetical clause is to indicate who is being addressed.
The first example seems somewhat different. The clause that interrupts the relationship between the verb of speaking εἶπεν and direct speech (italics) tells us the size of the audience addressed but doesn't directly encode syntactically the notion that the members of this group are the addressees. The addressee relationship is inferential and the function of the parenthetical clause is to relate the size of the group.
This may be nit picking but I couldn't find a good example of this sort of thing in Thucydides. Nothing like an exhaustive search, I looked at several forms of verbs of speaking that introduced speeches, found several examples of the second pattern but nothing like the first one. What led to to Thucydides was the grammars (Smyth, Cooper) claim Thucydides used TE solitarium for parenthetical constituents. I didn't, however, limit my search to samples that included TE solitarium.
postscript on text:
Acts 1:15 Καὶ ἐν ταῖς ἡμέραις ταύταις ἀναστὰς Πέτρος ἐν μέσῳ τῶν ἀδελφῶν εἶπεν· ἦν τε ὄχλος ὀνομάτων ἐπὶ τὸ αὐτὸ ὡσεὶ ἑκατὸν εἴκοσι·
 for τε read δὲ ὁ D(c), γὰρ ὁ D*, δὲ 056, 1611
BDF, and N. Turner favor δὲ. C.K. Barrett (ICC, Acts v1. Page 95) notes that the interruption of the parenthetical constituent is awkward regardless of τε/δὲ. M.Parsons & M. Culy, Acts: A handbook... p. is an abrupt narrative aside, better introduced by δὲ. See also S.H. Levinshon Discourse Features of New Testament Greek, 2000, P. 107 for discussion of the function of TE solitarium in discourse with Acts 1:15 as an example.
C. Stirling Bartholomew